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Appendix 1 to AMC 20-128A User's Manual

Available versions for ERULES-1963177438-6769

ED Decision 2003/12/RM found in: AMC-20 Amdt 22 - Airworthiness of Products, Parts and Appliances (May 2021)

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Appendix 1 to AMC 20-128A User’s Manual

ED Decision 2003/12/RM

RISK ANALYSIS METHODOLOGY for UNCONTAINED ENGINE/APU FAILURE

INDEX

1.0 GENERAL

2.0 SCOPE

3.0 FUNDAMENTAL COMPONENTS OF A SAFETY AND RISK ANALYSIS

4.0 ASSUMPTIONS

5.0 PLOTTING

6.0 METHODOLOGY – PROBABILITY ASSESSMENT

7.0 RESULTS ASSESSMENT

<table border="0" cellpadding="0" cellspacing="0" width="591"><tr><td valign="top" width="72">FIGURE 1</td><td valign="top" width="519">EXAMPLE – HAZARD TREE</td></tr><tr><td valign="top" width="72">FIGURE 2</td><td valign="top" width="519">EXAMPLE – SYSTEM LOADING MATRIX</td></tr><tr><td valign="top" width="72">FIGURE 3</td><td valign="top" width="519">TRI-SECTOR ROTOR BURST</td></tr><tr><td valign="top" width="72">FIGURE 4</td><td valign="top" width="519">TYPICAL LAYOUT OF SYSTEMS IN ROTOR PLANE</td></tr><tr><td valign="top" width="72">FIGURE 5</td><td valign="top" width="519">TRAJECTORY RANGE PLOTTING</td></tr><tr><td valign="top" width="72">FIGURE 6</td><td valign="top" width="519">TYPICAL TRAJECTORY PLOTTING</td></tr><tr><td valign="top" width="72">FIGURE 7</td><td valign="top" width="519">DEFINITION – THREAT WINDOW</td></tr><tr><td valign="top" width="72">FIGURE 8</td><td valign="top" width="519">SAMPLE ROTOR STAGE PLOTTING CHART</td></tr></table>

1.0 GENERAL

1.1 The design of aeroplane and engine systems and the location of the engines relative to critical systems and structure have a significant impact on survivability of the aeroplane following an uncontained engine failure. CS 23.903(b)(1) and 25.903(d)(1) of the EASA Certification Specifications (CS) require that design precautions be taken to minimise the hazard to the aeroplane due to uncontained failures of engine or auxiliary power unit (APU). [AMC 20-128A](#_DxCrossRefBm1701658079) provides guidance for demonstrating compliance with these requirements.

1.2 As a part of this compliance demonstration, it is necessary to quantitatively assess the risk of a catastrophic failure in the event of an uncontained engine failure. This User’s Manual describes an acceptable method for this purpose.

1.3 The objective of the risk analysis is to measure the remaining risk after prudent and practical design considerations have been taken. Since each aeroplane would have unique features which must be considered when applying the methods described in this manual, there should be some flexibility in the methods and procedures.

1.4 It is a preferred approach to use these methods throughout the development of an aeroplane design to identify problem areas at an early stage when appropriate design changes are least disruptive. It is also advisable to involve the European Aviation Safety Agency (EASA) in this process at an early stage when appropriate interpretation of the methodology and documentation requirements can be established.

1.5 It should be noted that although the risk analysis produces quantitative results, subjective assessments are inherent in the methods of the analysis regarding the criticality of specific types of aeroplane component failures. Assumptions for such assessments should be documented along with the numerical results.

1.6 Aeroplane manufacturers have each developed their own method of assessing the effects of rotor failure, as there are many ways to get to the same result. This User’s Manual identifies all the elements that should be contained in an analysis, so that it can be interpreted by a person not familiar with such a process.

1.7 The intent of this manual therefore is to aid in establishing how an analysis is prepared, without precluding any technological advances or existing proprietary processes.

1.8 AMC 20-128A makes allowance for the broad configuration of the aeroplane as such damage to the structure due to rotor failure generally allows for little flexibility in design. System lay-out within a rotor burst zone, however, can be optimized.

1.9 Damage to structure, which may involve stress analysis, generally can be analyzed separately, and later coordinated with simultaneous system effects.

1.10 For an analysis of the effects on systems due to a rotor failure the aeroplane must be evaluated as a whole; and a risk analysis must specifically highlight all critical cases identified which have any potential to result in a catastrophe.

1.11 Such an analysis can then be used to establish that reasonable precautions have been taken to minimise the hazards, and that the remaining hazards are an acceptable risk.

1.12 A safety and a risk analysis are interdependent, as the risk analysis must be based on the safety analysis.

The safety analysis therefore is the starting point that identifies potential hazardous or catastrophic effects from a rotor failure and is the basic tool to minimise the hazard in accordance with the guidelines of [AMC 20-128A](#_DxCrossRefBm1701658079).

1.13 The risk analysis subsequently assesses and quantifies the residual risk to the aeroplane.

2.0 SCOPE

The following describes the scope of analyses required to assess the aeroplane risk levels against the criteria set forth in Paragraph 10 of [AMC 20-128A](#_DxCrossRefBm1701658079).

2.1 Safety

Analysis is required to identify the critical hazards that may be numerically analyzed (hazards remaining after all practical design precautions have been taken).

Functional criticality will vary by aeroplane and may vary by flight phase.

Thorough understanding of each aeroplane structure and system functions is required to establish the criticality relative to each fragment trajectory path of the theoretical failure.

Assistance from experts within each discipline is typically required to assure accuracy of the analysis in such areas as effects of fuel tank penetration on leakage paths and ignition hazards, thrust level control (for loss of thrust assessment), structural capabilities (for fuselage impact assessment), aeroplane controllability (for control cables impact assessment), and fuel asymmetry.

2.2 Risk

For each remaining critical hazard, the following assessments may be prepared using the engine/APU failure models as defined in Paragraph 9 of [AMC 20-128A](#_DxCrossRefBm1701658079):

a. Flight mean risk for single 1/3 disc fragment.

b. Flight mean risk for single intermediate fragment.

c. Flight mean risk for alternate model (when used as an alternate to the 1/3 disc fragment and intermediate fragment).

d. Multiple 1/3 disc fragments for duplicated or multiplicated systems.

e. Specific risk for single 1/3 disc fragment and single intermediate fragment.

f. Specific risk for any single disc fragment that may result in catastrophic structural damage.

The risk level criteria for each failure model are defined in Paragraph 10 of [AMC 20-128A](#_DxCrossRefBm1701658079).

3.0 FUNDAMENTAL COMPONENTS OF A SAFETY AND RISK ANALYSIS

3.1 The logical steps for a complete analysis are:

a. Establish at the design definition the functional hazards that can arise from the combined or concurrent failures of individual systems, including multiplicated systems and critical structure.

b. Establish a Functional Hazard Tree (see Figure 1), or a System Matrix (see Figure 2) that identifies all system interdependencies and failure combinations that must be avoided (if possible) when locating equipment in the rotor burst impact area.

In theory, if this is carried out to the maximum, no critical system hazards other than opposite engine or fuel line hits would exist.

c. Establish the fragment trajectories and trajectory ranges both for translational and spread risk angles for each damage. Plot these on a chart or graph, and identify the trajectory ranges that could result in hazardous combinations (threats) as per the above system matrix or functional hazard analysis.

d. Apply risk factors, such as phase of flight or other, to these threats, and calculate the risk for each threat for each rotor stage.

e. Tabulate, summarize and average all cases.

3.2 In accordance with [AMC 20-128A](#_DxCrossRefBm1701658079) the risk to the aeroplane due to uncontained rotor failure is assessed to the effects, once such a failure has occurred.

The probability of occurrence of rotor failure, as analyzed with the probability methods of AMC 25.1309 (i.e. probability as a function of critical uncontained rotor failure rate and exposure time), does not apply.

3.3 The total risk level to the aeroplane, as identified by the risk analysis, is the mean value obtained by averaging the values of all rotor stages of all engines of the aeroplane, expressed as Flight Mean Risk.

4.0 ASSUMPTIONS

4.1 The following conservative assumptions, in addition to those in Paragraphs 10(a)(1), (2) and (3) of [AMC 20-128A](#_DxCrossRefBm1701658079), have been made in some previous analyses. However, each aeroplane design may have unique characteristics and therefore a unique basis for the safety assessment leading to the possibility of different assumptions. All assumptions should be substantiated within the analysis:

a. The 1/3 disc fragment as modeled in Paragraph 9(a) of the [AMC 20-128A](#_DxCrossRefBm1701658079) travels along a trajectory path that is tangential to the sector centroid locus, in the direction of rotor rotation (Refer to Figure 3).

The sector fragment rotates about its centroid without tumbling and sweeps a path equal to twice the greatest radius that can be struck from the sector centroid that intersects its periphery.

The fragment is considered to possess infinite energy, and therefore to be capable of severing lines, wiring, cables and unprotected structure in its path, and to be undeflected from its original trajectory unless deflection shields are fitted. However, protective shielding or an engine being impacted may be assumed to have sufficient mass to stop even the most energetic fragment.

b. The probability of release of debris within the maximum spread angle is uniformly distributed over all directions.

c. The effects of severed electrical wiring are dependent on the configuration of the affected system. In general, severed wiring is assumed to not receive inadvertent positive voltage for any significant duration.

d. Control cables that are struck by a fragment disconnect.

e. Hydraulically actuated, cable driven control surfaces, which do not have designated “fail to” settings, tend to fail to null when control cables are severed. Subsequent surface float is progressive and predictable.

f. Systems components are considered unserviceable if their envelope has been touched. In case of an engine being impacted, the nacelle structure may be regarded as engine envelope, unless damage is not likely to be hazardous.

g. Uncontained events involving in-flight penetration of fuel tanks will not result in fuel tank explosion.

h. Unpowered flight and off-airport landings, including ditching, may be assumed to be not catastrophic to the extent validated by accident statistics or other accepted factors.

i. Damage to structure essential for completion of flight is catastrophic (Ref. [AMC 20-128A](#_DxCrossRefBm1701658079), Paragraph 10.b(1)).

j. The flight begins when engine power is advanced for takeoff and ends after landing when turning off the runway.

5.0 PLOTTING

5.1 Cross-section and plan view layouts of the aeroplane systems in the ranges of the rotor burst impact areas should be prepared, either as drawings, or as computer models

These layouts should plot the precise location of the critical system components, including fuel and hydraulic lines, flight control cables, electric wiring harnesses and junction boxes, pneumatic and environmental system ducting, fire extinguishing; critical structure, etc.

5.2 For every rotor stage a plane is developed. Each of these planes contains a view of all the system components respective outer envelopes, which is then used to generate a cross-section. See Figure 4.

5.3 Models or drawings representing the various engine rotor stages and their fore and aft deviation are then generated.

5.4 The various trajectory paths generated for each engine rotor stage are then superimposed on the cross-section layouts of the station planes that are in the range of that potential rotor burst in order to study the effects (see Figure 5). Thus separate plots are generated for each engine rotor stage or rotor group.

To reduce the amount of an analysis the engine rotor stages may also be considered as groups, as applicable for the engine type, using the largest rotor stage diameter of the group.

5.5 These trajectory paths may be generated as follows and as shown in Figure 6:

a. Two tangent lines T1 are drawn between the locus of the centroid and the target envelope.

b. At the tangent line touch points, lines N1 and N2 normal to the tangent lines, are drawn with the length equal to the radius of the fragment swept path (as also shown in Figure 1).

c. Tangent lines T2 are drawn between the terminal point of the normal lines and the locus of the centroid. The angle between these two tangent lines is the translational risk angle.

5.6 The entry and exit angles are then calculated.

5.7 The initial angle of intersection and the final angle of intersection are recorded, and the trajectories in between are considered to be the range of trajectories in which this particular part would be impacted by a rotor sector, and destroyed (i.e. the impact area).

The intersections thus recorded are then entered on charts in tabular form so that the simultaneous effects can be studied. Refer to Figure 8.

Thus it will be seen that the total systems’ effects can be determined and the worst cases identified.

5.9 If a potentially serious multiple system damage case is identified, then a more detailed analysis of the trajectory range will be carried out by breaking the failure case down into the specific fore-aft spread angle, using the individual rotor stage width instead of combined groups, if applicable.

6.0 METHODOLOGY – PROBABILITY ASSESSMENT

6.1 Those rotor burst cases that have some potential of causing a catastrophe are evaluated in the analysis in an attempt to quantify an actual probability of a catastrophe, which will, in all cases, depend on the following factors:

a. The location of the engine that is the origin of the fragment, and its direction of rotation.

b. The location of critical systems and critical structure.

c. The rotor stage and the fragment model.

d. The translational trajectory of the rotor fragment,

e. The specific spread angle range of the fragment.

f. The specific phase of the flight at which the failure occurs.

g. The specific risk factor associated with any particular loss of function.

6.2 Engine Location

The analysis should address the effects on systems during one flight after a single rotor burst has occurred, with a probability of 1.0. As the cause may be any one of the engines, the risk from each engine is later averaged for the number of engines.

The analysis trajectory charts will then clearly show that certain system damage is unique to rotor fragments from a particular engine due to the direction of rotation, or, that for similar system damage the trajectory range varies considerably between engines.

A risk summary should table each engine case separately with the engine location included.

6.3 Rotor Element

The probability of rotor failure is assumed to be 1.0 for each of all rotor stages. For the analysis the individual risk(s) from each rotor stage of the engine should be assessed and tabled.

6.4 Translational Risk Angle

The number of degrees of included arc (out of 360) at which a fragment intersects the component/structure being analyzed. Refer to Figure 6 and Figure 7.

6.5 Trajectory Probability (P)

The probability of a liberated rotor fragment leaving the engine case is equal over 360, thus the probability P of that fragment hitting a system component is the identified Translational Risk Angle ɸ in degrees °, divided by 360, i.e.

![EASA EAR image](/static/files/file_ftLzkYEblJP/image048.png)

![EASA EAR image](/static/files/file_ftLzkYEblJP/image049.png)

6.6 Spread Angle

If the failure model of the analysis assumes a (fore and aft) spread of ± 5°, then the spread angle is a total of 10°. If a critical component can only be hit at a limited position within that spread, then the exposure of that critical component can then be factored according to the longitudinal position within the spread angle, e.g.:

![EASA EAR image](/static/files/file_ftLzkYEblJP/image050.png)

If a component can only be hit at the extreme forward range of +4° to +5°, then the factor is .1 (for one degree out of 10).

6.7 Threat Window

The definition of a typical threat window is shown in Figure 7.

6.8 Phase of Flight

Certain types of system damage may be catastrophic only during a specific portion of the flight profile, such as a strike on the opposite engine during take-off after V1 (i.e. a probability of 1.0), while with altitude a straight-ahead landing may be possible under certain favourable conditions (e.g. a probability of less than 1.0). The specific case can then be factored accordingly.

6.8.1 The most likely time for an uncontained rotor failure to occur is during take-off, when the engine is under highest stress. Using the industry accepted standards for the percentage of engine failures occurring within each flight phase, the following probabilities are assumed:

<table border="1" cellpadding="0" cellspacing="0" width="491"><tr><td valign="top" width="245">Take-off before V1</td><td valign="top" width="245">35%</td></tr><tr><td valign="top" width="245">V1 to first power reduction</td><td valign="top" width="245">20%</td></tr><tr><td valign="top" width="245">Climb</td><td valign="top" width="245">22%</td></tr><tr><td valign="top" width="245">Cruise</td><td valign="top" width="245">14%</td></tr><tr><td valign="top" width="245">Descent</td><td valign="top" width="245">3%</td></tr><tr><td valign="top" width="245">Approach</td><td valign="top" width="245">2%</td></tr><tr><td valign="top" width="245">Landing/Reverse</td><td valign="top" width="245">4%</td></tr></table>

6.8.2 The flight phase failure distribution above is used in the calculations of catastrophic risk for all cases where this risk varies with flight phase.

![EASA EAR image](/static/files/file_ftLzkYEblJP/image051.png)

6.9 Other Risk Factors

Risks such as fire, loss of pressurization, etc., are individually assessed for each case where applicable, using conservative engineering judgment. This may lead to a probability of catastrophe (i.e., risk factor) smaller than 1.0.

6.9.1 The above probabilities and factors are used in conjunction with the critical trajectory range defined to produce a probability of the specific event occurring from any random rotor burst.

This value is then factored by the "risk" factor assessed for the case, to derive a calculated probability of catastrophe for each specific case.

Typical conditional probability values for total loss of thrust causing catastrophic consequences are:

<table border="1" cellpadding="0" cellspacing="0" width="489"><tr><td valign="top" width="264">Phase</td><td valign="top" width="112">Dp</td><td valign="top" width="112">Risk</td></tr><tr><td valign="top" width="264">T.O.–V1 to first power reduction</td><td valign="top" width="112">0.20</td><td valign="top" width="112">1.0</td></tr><tr><td valign="top" width="264">Climb</td><td valign="top" width="112">0.22</td><td valign="top" width="112">0.4</td></tr><tr><td valign="top" width="264">Cruise</td><td valign="top" width="112">0.14</td><td valign="top" width="112">0.2</td></tr><tr><td valign="top" width="264">Descent</td><td valign="top" width="112">0.03</td><td valign="top" width="112">0.4</td></tr><tr><td valign="top" width="264">Approach</td><td valign="top" width="112">0.02</td><td valign="top" width="112">0.4</td></tr></table>

6.10 All individual case probabilities are then tabled and summarised.

6.11 The flight mean values are obtained by averaging those for all discs or rotor stages on all engines across a nominal flight profile.

The following process may be used to calculate the flight mean value for each Failure Model:

a. Establish from the table in Figure 8 the threat windows where, due to combination of individual damages, a catastrophic risk exists.

b. For each stage case calculate the risk for all Critical Hazards

c. For each stage case apply all risk factors, and, if applicable, factor for Flight Phase-Failure distribution

d. For each engine, average all stages over the total number of engine stages

e. For each aeroplane, average all engines over the number of engines.

7.0 RESULTS ASSESSMENT

7.1 An applicant may show compliance with CS 23.903(b)(1) and CS 25.903(d)(1) using guidelines set forth in [AMC 20-128A](#_DxCrossRefBm1701658079). The criteria contained in the AMC may be used to show that:

a. Practical design precautions have been taken to minimise the damage that can be caused by uncontained engine debris, and

b. Acceptable risk levels, as specified in [AMC 20-128A](#_DxCrossRefBm1701658079), Paragraph 10, have been achieved for each critical Failure Model.

7.2 The summary of the applicable risk level criteria is shown in Table 1 below.

Table 1 Summary of Acceptable Risk Level Criteria

<table border="1" cellpadding="0" cellspacing="0" width="533"><tr><td valign="top" width="291">Requirement</td><td valign="top" width="242">Criteria</td></tr><tr><td valign="top" width="291">Average 1/3 Disc Fragment</td><td valign="top" width="242">1 in 20</td></tr><tr><td valign="top" width="291">Average Intermediate Fragment</td><td valign="top" width="242">1 in 40</td></tr><tr><td valign="top" width="291">Average Alternate Model</td><td valign="top" width="242">1 in 20 @ ± 5 degree Spread Angle</td></tr><tr><td valign="top" width="291">Multiple Disc Fragments</td><td valign="top" width="242">1 in 10</td></tr><tr><td valign="top" width="291">Any single fragment (except for structural damage)</td><td valign="top" width="242">2 x corresponding average criterion</td></tr></table>

![EASA EAR image](/static/files/file_ftLzkYEblJP/image052.png)

EXAMPLE – HAZARD TREE

FIGURE 1

<table border="1" cellpadding="0" cellspacing="0" width="608"><tr><td valign="top" width="79">LOC</td><td valign="top" width="143">COMPONENT</td><td valign="top" width="143">DAMAGE TO</td><td valign="top" width="143">SYSTEM LOADED</td><td valign="top" width="100">DETAIL</td></tr><tr><td valign="top" width="79">LEFT</td><td valign="top" width="143">AILERON</td><td valign="top" width="143">CABLES/SURFACE</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#1 &amp; #3</td></tr><tr><td valign="top" width="79">RIGHT</td><td valign="top" width="143">AILERON</td><td valign="top" width="143">CABLES/SURFACE</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#2 &amp; #3</td></tr><tr><td valign="top" width="79">LEFT</td><td valign="top" width="143">SPOILER - OUTBD MULTI-FUNCTION</td><td valign="top" width="143">CONTROL/SURFACE</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#1</td></tr><tr><td valign="top" width="79">RIGHT</td><td valign="top" width="143">SPOILER - OUTBD MULTI-FUNCTION</td><td valign="top" width="143">CONTROL/SURFACE</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#1</td></tr><tr><td valign="top" width="79">LEFT</td><td valign="top" width="143">FLAP-OUTBD</td><td valign="top" width="143">TRACK/SURFACE</td><td valign="top" width="143">ELECTRICAL POWER</td><td valign="top" width="100">AC BUS1AC ESS</td></tr><tr><td valign="top" width="79">RIGHT</td><td valign="top" width="143">FLAP-OUTBD</td><td valign="top" width="143">TRACK/SURFACE</td><td valign="top" width="143">ELECTRICAL POWER</td><td valign="top" width="100">AC BUS1AC ESS</td></tr><tr><td valign="top" width="79">LEFT</td><td valign="top" width="143">RUDDER</td><td valign="top" width="143">CABLE</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#1,#2&amp;#3</td></tr><tr><td valign="top" width="79">RIGHT</td><td valign="top" width="143">RUDDER</td><td valign="top" width="143">CABLE</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#1,#2&amp;#3</td></tr><tr><td valign="top" width="79">LEFT</td><td valign="top" width="143">ELEVATOR</td><td valign="top" width="143">CABLESNote 1</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#1 &amp; #3</td></tr><tr><td valign="top" width="79">RIGHT</td><td valign="top" width="143">ELEVATOR</td><td valign="top" width="143">CABLESNote 1</td><td valign="top" width="143">HYDRAULIC POWER</td><td valign="top" width="100">#2 &amp; #3</td></tr><tr><td valign="top" width="79">CHAN1</td><td valign="top" width="143">PITCH TRIM</td><td valign="top" width="143">CONTROL/POWERNote 2</td><td valign="top" width="143">ELECTRICAL POWER</td><td valign="top" width="100">AC BUS1DC BUS1</td></tr><tr><td valign="top" width="79">CHAN2</td><td valign="top" width="143">PITCH TRIM</td><td valign="top" width="143">CONTROL/POWERNote 2</td><td valign="top" width="143">ELECTRICAL POWER</td><td valign="top" width="100">AC ESSDC ESS</td></tr></table>

FLIGHT CONTROLS – SYSTEM LOADING

Note 1:

Same fragment path must not sever:

ON-SIDE cables + OFF-SIDE hydraulic system + HYDRAULIC PWR #3

e.g.: Left elevator cable and HYDRAULIC PWR #2 and #3 or,

Right elevator cable and HYDRAULIC PWR # 1 and # 3

Note 2:

Same fragment path must not sever:

— Both CHAN1 and CHAN2 circuits

— ON-SIDE control circuit + OFF-SIDE power circuit

— OFF-SIDE control circuit + ON-SIDE power circuit

EXAMPLE – SYSTEM LOADING MATRIX

FIGURE 2

![EASA EAR image](/static/files/file_ftLzkYEblJP/image053.png)

TRI-SECTOR ROTOR BURST

FIGURE 3

![EASA EAR image](/static/files/file_ftLzkYEblJP/image054.png)

TYPICAL LAYOUT OF SYSTEMS IN ROTOR PLANE

FIGURE 4

![EASA EAR image](/static/files/file_ftLzkYEblJP/image055.png)

TRAJECTORY RANGE PLOTTING

FIGURE 5

![EASA EAR image](/static/files/file_ftLzkYEblJP/image056.png)

TYPICAL TRAJECTORY PLOTTING

FIGURE 6

![EASA EAR image](/static/files/file_ftLzkYEblJP/image057.png)

DEFINITION - THREAT WINDOW

FIGURE 7

![EASA EAR image](/static/files/file_ftLzkYEblJP/image058.png)

Appendix 1 to AMC 20-128A User’s Manual

ED Decision 2003/12/RM

RISK ANALYSIS METHODOLOGY for
UNCONTAINED ENGINE/APU FAILURE

INDEX

1.0       GENERAL

2.0       SCOPE

3.0       FUNDAMENTAL
COMPONENTS OF A SAFETY AND RISK ANALYSIS

4.0       ASSUMPTIONS

5.0       PLOTTING

6.0       METHODOLOGY
– PROBABILITY ASSESSMENT

7.0       RESULTS
ASSESSMENT

<table border="0" cellpadding="0" cellspacing="0" width="591">
<tr>
<td valign="top" width="72">
FIGURE 1
</td>
<td valign="top" width="519">
EXAMPLE – HAZARD TREE
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 2
</td>
<td valign="top" width="519">
EXAMPLE – SYSTEM LOADING MATRIX
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 3
</td>
<td valign="top" width="519">
TRI-SECTOR ROTOR BURST
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 4
</td>
<td valign="top" width="519">
TYPICAL LAYOUT OF SYSTEMS IN ROTOR PLANE
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 5
</td>
<td valign="top" width="519">
TRAJECTORY RANGE PLOTTING
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 6
</td>
<td valign="top" width="519">
TYPICAL TRAJECTORY PLOTTING
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 7
</td>
<td valign="top" width="519">
DEFINITION – THREAT WINDOW
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 8
</td>
<td valign="top" width="519">
SAMPLE ROTOR STAGE PLOTTING CHART
</td>
</tr>
</table>

1.0       GENERAL

1.1       The design
of aeroplane and engine systems and the location of the engines relative to
critical systems and structure have a significant impact on survivability of
the aeroplane following an uncontained engine failure. CS 23.903(b)(1) and
25.903(d)(1) of the EASA Certification Specifications (CS) require that design
precautions be taken to minimise the hazard to the aeroplane due to
uncontained failures of engine or auxiliary power unit (APU). [AMC 20-128A](#_DxCrossRefBm1926189323) provides guidance for
demonstrating compliance with these requirements.

1.2       As a part
of this compliance demonstration, it is necessary to quantitatively assess the
risk of a catastrophic failure in the event of an uncontained engine failure.
This User’s Manual describes an acceptable method for this purpose.

1.3       The
objective of the risk analysis is to measure the remaining risk after prudent
and practical design considerations have been taken. Since each aeroplane
would have unique features which must be considered when applying the methods
described in this manual, there should be some flexibility in the methods and
procedures.

1.4       It is a
preferred approach to use these methods throughout the development of an
aeroplane design to identify problem areas at an early stage when appropriate
design changes are least disruptive. It is also advisable to involve the
European Aviation Safety Agency (EASA) in this process at an early stage when
appropriate interpretation of the methodology and documentation requirements
can be established.

1.5       It should
be noted that although the risk analysis produces quantitative results,
subjective assessments are inherent in the methods of the analysis regarding
the criticality of specific types of aeroplane component failures. Assumptions
for such assessments should be documented along with the numerical results.

1.6       Aeroplane
manufacturers have each developed their own method of assessing the effects of
rotor failure, as there are many ways to get to the same result. This User’s
Manual identifies all the elements that should be contained in an analysis, so
that it can be interpreted by a person not familiar with such a process.

1.7       The intent
of this manual therefore is to aid in establishing how an analysis is
prepared, without precluding any technological advances or existing
proprietary processes.

1.8       AMC 20-128A
makes allowance for the broad configuration of the aeroplane as such damage to
the structure due to rotor failure generally allows for little flexibility in
design. System lay-out within a rotor burst zone, however, can be optimized.

1.9       Damage to
structure, which may involve stress analysis, generally can be analyzed
separately, and later coordinated with simultaneous system effects.

1.10    For an
analysis of the effects on systems due to a rotor failure the aeroplane must
be evaluated as a whole; and a risk analysis must specifically highlight all
critical cases identified which have any potential to result in a catastrophe.

1.11    Such an
analysis can then be used to establish that reasonable precautions have been
taken to minimise the hazards, and that the remaining hazards are an
acceptable risk.

1.12    A safety and
a risk analysis are interdependent, as the risk analysis must be based on the
safety analysis.

The safety analysis therefore is the starting point that
identifies potential hazardous or catastrophic effects from a rotor failure
and is the basic tool to minimise the hazard in accordance with the guidelines
of [AMC 20-128A](#_DxCrossRefBm1926189323).

1.13    The risk
analysis subsequently assesses and quantifies the residual risk to the
aeroplane.

2.0       SCOPE

The following describes the scope of analyses required to
assess the aeroplane risk levels against the criteria set forth in Paragraph
10 of [AMC 20-128A](#_DxCrossRefBm1926189323).

2.1       Safety

Analysis is required to identify the critical hazards that
may be numerically analyzed (hazards remaining after all practical design
precautions have been taken).

Functional criticality will vary by aeroplane and may vary by
flight phase.

Thorough understanding of each aeroplane structure and system
functions is required to establish the criticality relative to each fragment
trajectory path of the theoretical failure.

Assistance from experts within each discipline is typically
required to assure accuracy of the analysis in such areas as effects of fuel
tank penetration on leakage paths and ignition hazards, thrust level control
(for loss of thrust assessment), structural capabilities (for fuselage impact
assessment), aeroplane controllability (for control cables impact assessment),
and fuel asymmetry.

2.2       Risk

For each remaining critical hazard, the following assessments
may be prepared using the engine/APU failure models as defined in Paragraph 9
of [AMC 20-128A](#_DxCrossRefBm1926189323):

a.         Flight mean
risk for single 1/3 disc fragment.

b.        Flight mean
risk for single intermediate fragment.

c.         Flight
mean risk for alternate model (when used as an alternate to the 1/3 disc
fragment and intermediate fragment).

d.        Multiple
1/3 disc fragments for duplicated or multiplicated systems.

e.        Specific
risk for single 1/3 disc fragment and single intermediate fragment.

f.         Specific
risk for any single disc fragment that may result in catastrophic structural
damage.

The risk level criteria for each failure model are defined in
Paragraph 10 of [AMC 20-128A](#_DxCrossRefBm1926189323).

3.0       FUNDAMENTAL
COMPONENTS OF A SAFETY AND RISK ANALYSIS

3.1       The logical
steps for a complete analysis are:

a.         Establish
at the design definition the functional hazards that can arise from the
combined or concurrent failures of individual systems, including multiplicated
systems and critical structure.

b.        Establish a
Functional Hazard Tree (see Figure 1), or a System Matrix (see Figure 2) that
identifies all system interdependencies and failure combinations that must be
avoided (if possible) when locating equipment in the rotor burst impact area.

In theory, if this is carried out to the maximum, no critical
system hazards other than opposite engine or fuel line hits would exist.

c.         Establish
the fragment trajectories and trajectory ranges both for translational and
spread risk angles for each damage. Plot these on a chart or graph, and
identify the trajectory ranges that could result in hazardous combinations
(threats) as per the above system matrix or functional hazard analysis.

d.        Apply risk
factors, such as phase of flight or other, to these threats, and calculate the
risk for each threat for each rotor stage.

e.        Tabulate,
summarize and average all cases.

3.2       In
accordance with [AMC 20-128A](#_DxCrossRefBm1926189323) the
risk to the aeroplane due to uncontained rotor failure is assessed to the
effects, once such a failure has occurred.

The probability of occurrence of rotor failure, as analyzed
with the probability methods of AMC 25.1309 (i.e. probability as a function of
critical uncontained rotor failure rate and exposure time), does not apply.

3.3       The total
risk level to the aeroplane, as identified by the risk analysis, is the mean
value obtained by averaging the values of all rotor stages of all engines of
the aeroplane, expressed as Flight Mean Risk.

4.0       ASSUMPTIONS

4.1       The
following conservative assumptions, in addition to those in Paragraphs
10(a)(1), (2) and (3) of [AMC 20-128A](#_DxCrossRefBm1926189323),
have been made in some previous analyses. However, each aeroplane design may
have unique characteristics and therefore a unique basis for the safety
assessment leading to the possibility of different assumptions. All
assumptions should be substantiated within the analysis:

a.         The 1/3
disc fragment as modeled in Paragraph 9(a) of the [AMC 20-128A](#_DxCrossRefBm1926189323) travels along a
trajectory path that is tangential to the sector centroid locus, in the
direction of rotor rotation (Refer to Figure 3).

The sector fragment rotates about its centroid without
tumbling and sweeps a path equal to twice the greatest radius that can be
struck from the sector centroid that intersects its periphery.

The fragment is considered to possess infinite energy, and
therefore to be capable of severing lines, wiring, cables and unprotected
structure in its path, and to be undeflected from its original trajectory
unless deflection shields are fitted. However, protective shielding or an
engine being impacted may be assumed to have sufficient mass to stop even the
most energetic fragment.

b.        The
probability of release of debris within the maximum spread angle is uniformly
distributed over all directions.

c.         The
effects of severed electrical wiring are dependent on the configuration of the
affected system. In general, severed wiring is assumed to not receive
inadvertent positive voltage for any significant duration.

d.        Control
cables that are struck by a fragment disconnect.

e.        Hydraulically
actuated, cable driven control surfaces, which do not have designated “fail
to” settings, tend to fail to null when control cables are severed. Subsequent
surface float is progressive and predictable.

f.         Systems
components are considered unserviceable if their envelope has been touched. In
case of an engine being impacted, the nacelle structure may be regarded as
engine envelope, unless damage is not likely to be hazardous.

g.         Uncontained
events involving in-flight penetration of fuel tanks will not result in fuel
tank explosion.

h.        Unpowered
flight and off-airport landings, including ditching, may be assumed to be not
catastrophic to the extent validated by accident statistics or other accepted
factors.

i.          Damage to
structure essential for completion of flight is catastrophic (Ref. [AMC 20-128A](#_DxCrossRefBm1926189323), Paragraph 10.b(1)).

j.          The
flight begins when engine power is advanced for takeoff and ends after landing
when turning off the runway.

5.0       PLOTTING

5.1       Cross-section
and plan view layouts of the aeroplane systems in the ranges of the rotor
burst impact areas should be prepared, either as drawings, or as computer
models

These layouts should plot the precise location of the
critical system components, including fuel and hydraulic lines, flight control
cables, electric wiring harnesses and junction boxes, pneumatic and
environmental system ducting, fire extinguishing; critical structure, etc.

5.2       For every
rotor stage a plane is developed. Each of these planes contains a view of all
the system components respective outer envelopes, which is then used to
generate a cross-section. See Figure 4.

5.3       Models or
drawings representing the various engine rotor stages and their fore and aft
deviation are then generated.

5.4       The various
trajectory paths generated for each engine rotor stage are then superimposed
on the cross-section layouts of the station planes that are in the range of
that potential rotor burst in order to study the effects (see Figure 5). Thus
separate plots are generated for each engine rotor stage or rotor group.

To reduce the amount of an analysis the engine rotor stages
may also be considered as groups, as applicable for the engine type, using the
largest rotor stage diameter of the group.

5.5       These
trajectory paths may be generated as follows and as shown in Figure 6:

a.         Two
tangent lines T1 are drawn between the locus of the centroid and the target
envelope.

b.        At the
tangent line touch points, lines N1 and N2 normal to the tangent lines, are
drawn with the length equal to the radius of the fragment swept path (as also
shown in Figure 1).

c.         Tangent
lines T2 are drawn between the terminal point of the normal lines and the
locus of the centroid. The angle between these two tangent lines is the
translational risk angle.

5.6       The entry
and exit angles are then calculated.

5.7       The initial
angle of intersection and the final angle of intersection are recorded, and
the trajectories in between are considered to be the range of trajectories in
which this particular part would be impacted by a rotor sector, and destroyed
(i.e. the impact area).

The intersections thus recorded are then entered on charts in
tabular form so that the simultaneous effects can be studied. Refer to Figure
8.

Thus it will be seen that the total systems’ effects can be
determined and the worst cases identified.

5.9       If a
potentially serious multiple system damage case is identified, then a more
detailed analysis of the trajectory range will be carried out by breaking the
failure case down into the specific fore-aft spread angle, using the
individual rotor stage width instead of combined groups, if applicable.

6.0       METHODOLOGY
– PROBABILITY ASSESSMENT

6.1       Those rotor
burst cases that have some potential of causing a catastrophe are evaluated in
the analysis in an attempt to quantify an actual probability of a catastrophe,
which will, in all cases, depend on the following factors:

a.         The
location of the engine that is the origin of the fragment, and its direction
of rotation.

b.        The
location of critical systems and critical structure.

c.         The rotor
stage and the fragment model.

d.        The
translational trajectory of the rotor fragment,

e.        The
specific spread angle range of the fragment.

f.         The
specific phase of the flight at which the failure occurs.

g.         The
specific risk factor associated with any particular loss of function.

6.2       Engine
Location

The analysis should address the effects on systems during one
flight after a single rotor burst has occurred, with a probability of 1.0. As
the cause may be any one of the engines, the risk from each engine is later
averaged for the number of engines.

The analysis trajectory charts will then clearly show that
certain system damage is unique to rotor fragments from a particular engine
due to the direction of rotation, or, that for similar system damage the
trajectory range varies considerably between engines.

A risk summary should table each engine case separately with
the engine location included.

6.3       Rotor
Element

The probability of rotor failure is assumed to be 1.0 for
each of all rotor stages. For the analysis the individual risk(s) from each
rotor stage of the engine should be assessed and tabled.

6.4       Translational
Risk Angle

The number of degrees of included arc (out of 360) at which a
fragment intersects the component/structure being analyzed. Refer to Figure 6
and Figure 7.

6.5       Trajectory
Probability (P)

The probability of a liberated rotor fragment leaving the
engine case is equal over 360, thus the probability P of that fragment
hitting a system component is the identified Translational Risk Angle ɸ in
degrees °, divided by 360, i.e.

if !msEquation?![Aviation.Bot AI suggestion, not from EASA source: P = ϕ / 360](/static/files/file_tNNDI2wQkpg/image057.png)

if !msEquation?![Aviation.Bot AI suggestion, not from EASA source: \[\frac{\phi 1 - \phi 2}{360}\]](/static/files/file_tNNDI2wQkpg/image058.png)

6.6       Spread
Angle

If the failure model of the analysis assumes a (fore and aft)
spread of ± 5°, then the spread angle is a total of 10°. If a critical
component can only be hit at a limited position within that spread, then the
exposure of that critical component can then be factored according to the
longitudinal position within the spread angle, e.g.:

if !msEquation?![Aviation.Bot AI suggestion, not from EASA source: \[\frac{\psi 2 - \psi 1}{\textit{spread angle}}\]](/static/files/file_tNNDI2wQkpg/image059.png)

If a component can only be hit at the extreme forward range
of +4° to +5°, then the factor is .1 (for one degree out of 10).

6.7       Threat
Window

The definition of a typical threat window is shown in Figure
7.

6.8       Phase of
Flight

Certain types of system damage may be catastrophic only
during a specific portion of the flight profile, such as a strike on the
opposite engine during take-off after V1 (i.e. a probability of 1.0), while
with altitude a straight-ahead landing may be possible under certain
favourable conditions (e.g. a probability of less than 1.0). The specific case
can then be factored accordingly.

6.8.1   The most
likely time for an uncontained rotor failure to occur is during take-off, when
the engine is under highest stress. Using the industry accepted standards for
the percentage of engine failures occurring within each flight phase, the
following probabilities are assumed:

<table border="1" cellpadding="0" cellspacing="0" width="491">
<tr>
<td valign="top" width="245">
Take-off
 before V1
</td>
<td valign="top" width="245">
35%
</td>
</tr>
<tr>
<td valign="top" width="245">
V1
 to first power reduction
</td>
<td valign="top" width="245">
20%
</td>
</tr>
<tr>
<td valign="top" width="245">
Climb
</td>
<td valign="top" width="245">
22%
</td>
</tr>
<tr>
<td valign="top" width="245">
Cruise
</td>
<td valign="top" width="245">
14%
</td>
</tr>
<tr>
<td valign="top" width="245">
Descent
</td>
<td valign="top" width="245">
3%
</td>
</tr>
<tr>
<td valign="top" width="245">
Approach
</td>
<td valign="top" width="245">
2%
</td>
</tr>
<tr>
<td valign="top" width="245">
Landing/Reverse
</td>
<td valign="top" width="245">
4%
</td>
</tr>
</table>

6.8.2   The flight
phase failure distribution above is used in the calculations of catastrophic
risk for all cases where this risk varies with flight phase.

if !msEquation?![Aviation.Bot AI suggestion, not from EASA source: \[Dp = \frac{P_{flight\ phase\ \%}}{100}\]](/static/files/file_tNNDI2wQkpg/image060.png)

6.9       Other Risk
Factors

Risks such as fire, loss of pressurization, etc., are
individually assessed for each case where applicable, using conservative
engineering judgment. This may lead to a probability of catastrophe (i.e.,
risk factor) smaller than 1.0.

6.9.1   The above
probabilities and factors are used in conjunction with the critical trajectory
range defined to produce a probability of the specific event occurring from
any random rotor burst.

This value is then factored by the "risk" factor
assessed for the case, to derive a calculated probability of catastrophe for
each specific case.

Typical conditional probability values for total loss of
thrust causing catastrophic consequences are:

<table border="1" cellpadding="0" cellspacing="0" width="489">
<tr>
<td valign="top" width="264">
Phase
</td>
<td valign="top" width="112">
Dp
</td>
<td valign="top" width="112">
Risk
</td>
</tr>
<tr>
<td valign="top" width="264">
T.O.–V1
 to first power reduction
</td>
<td valign="top" width="112">
0.20
</td>
<td valign="top" width="112">
1.0
</td>
</tr>
<tr>
<td valign="top" width="264">
Climb
</td>
<td valign="top" width="112">
0.22
</td>
<td valign="top" width="112">
0.4
</td>
</tr>
<tr>
<td valign="top" width="264">
Cruise
</td>
<td valign="top" width="112">
0.14
</td>
<td valign="top" width="112">
0.2
</td>
</tr>
<tr>
<td valign="top" width="264">
Descent
</td>
<td valign="top" width="112">
0.03
</td>
<td valign="top" width="112">
0.4
</td>
</tr>
<tr>
<td valign="top" width="264">
Approach
</td>
<td valign="top" width="112">
0.02
</td>
<td valign="top" width="112">
0.4
</td>
</tr>
</table>

6.10    All individual
case probabilities are then tabled and summarised.

6.11    The flight
mean values are obtained by averaging those for all discs or rotor stages on
all engines across a nominal flight profile.

The following process may be used to calculate the flight
mean value for each Failure Model:

a.         Establish
from the table in Figure 8 the threat windows where, due to combination of
individual damages, a catastrophic risk exists.

b.        For each
stage case calculate the risk for all Critical Hazards

c.         For each
stage case apply all risk factors, and, if applicable, factor for Flight
Phase-Failure distribution

d.        For each
engine, average all stages over the total number of engine stages

e.        For each
aeroplane, average all engines over the number of engines.

7.0       RESULTS
ASSESSMENT

7.1       An
applicant may show compliance with CS 23.903(b)(1) and CS 25.903(d)(1) using
guidelines set forth in [AMC 20-128A](#_DxCrossRefBm1926189323).
The criteria contained in the AMC may be used to show that:

a.         Practical
design precautions have been taken to minimise the damage that can be caused
by uncontained engine debris, and

b.        Acceptable
risk levels, as specified in [AMC 20-128A](#_DxCrossRefBm1926189323),
Paragraph 10, have been achieved for each critical Failure Model.

7.2       The summary
of the applicable risk level criteria is shown in Table 1 below.

Table 1
Summary of Acceptable Risk Level Criteria

<table border="1" cellpadding="0" cellspacing="0" width="533">
<tr>
<td valign="top" width="291">
Requirement
</td>
<td valign="top" width="242">
Criteria
</td>
</tr>
<tr>
<td valign="top" width="291">
Average
 1/3 Disc Fragment
</td>
<td valign="top" width="242">
1
 in 20
</td>
</tr>
<tr>
<td valign="top" width="291">
Average
 Intermediate Fragment
</td>
<td valign="top" width="242">
1
 in 40
</td>
</tr>
<tr>
<td valign="top" width="291">
Average
 Alternate Model
</td>
<td valign="top" width="242">
1
 in 20 @ ± 5 degree Spread Angle
</td>
</tr>
<tr>
<td valign="top" width="291">
Multiple
 Disc Fragments
</td>
<td valign="top" width="242">
1
 in 10
</td>
</tr>
<tr>
<td valign="top" width="291">
Any
 single fragment (except for structural damage)
</td>
<td valign="top" width="242">
2
 x corresponding average criterion
</td>
</tr>
</table>

![Aviation.Bot AI suggestion, not from EASA source: The image displays a hierarchical flowchart illustrating the "ANALYSIS OF HAZARD" for uncontained engine/APU failure, detailing various potential hazards and their sub-categories.

Detailed Description:
The image is a flowchart composed of rectangular nodes with black borders and white backgrounds, containing black text, connected by solid black lines.
At the top, there is a single root node labeled "ANALYSIS OF HAZARD".
A vertical line descends from "ANALYSIS OF HAZARD" and branches horizontally to connect to five primary hazard categories, arranged from left to right:
1.  "ESSENTIAL SYSTEMS"
2.  "FIRES"
3.  "LOSS OF THRUST"
4.  "STRUCTURE"
5.  "OPERATION"

From "ESSENTIAL SYSTEMS", a vertical line descends and branches horizontally to connect to five sub-categories, arranged from left to right at the bottom of the chart:
*   "HYDRAULICS"
*   "NOSE STEER MAIN BRAKES"
*   "ELECTRICAL POWER"
*   "FLIGHT CONTROLS"
*   "PASS. OXYGEN"

From "FIRES", a vertical line descends and branches horizontally to connect to two sub-categories:
*   "MAIN TANK DRY BAY" (left)
*   "FIREX SYSTEM" (right)
From "MAIN TANK DRY BAY", a vertical line descends and branches horizontally to connect to three further sub-categories:
*   "ABORTED TAKE-OFF" (left)
*   "FUEL FEED SHUT-OFF" (middle)
*   "TANK ENTRY" (right)
From "ABORTED TAKE-OFF", a vertical line descends and branches horizontally to connect to three further sub-categories:
*   "FUSELAGE ENTRY" (left)
*   "ELECTRICAL WIRING" (middle)
*   "HYDRAULIC EQUIPMENT" (right)

From "LOSS OF THRUST", a vertical line descends and branches horizontally to connect to four sub-categories:
*   "DAMAGE TO FUEL FEED" (left)
*   "INTER-ENGINE DAMAGE" (middle-left)
*   "DAMAGE TO CONTROLS" (middle-right)
*   "BLEED AIR SYSTEM" (right)

From "STRUCTURE", a vertical line descends and branches horizontally to connect to two sub-categories:
*   "WING" (left)
*   "FUSELAGE" (right)
From "WING", a vertical line descends and branches horizontally to connect to two further sub-categories:
*   "STRENGTH" (left)
*   "FLUTTER" (right)
From "FUSELAGE", a vertical line descends and branches horizontally to connect to two further sub-categories:
*   "STRENGTH" (left)
*   "DECOMPRESSION" (right)

From "OPERATION", a vertical line descends and branches horizontally to connect to two sub-categories:
*   "FLIGHT CREW INCAPACITANCE" (left)
*   "RANGE" (right)

Contextual Linkage:
The flowchart visually represents a hierarchical decomposition of potential hazards. The connections between nodes indicate a breakdown from a broader hazard category to more specific sub-categories or consequences. For instance, "ANALYSIS OF HAZARD" is the overarching subject, which is then broken down into primary hazard types like "FIRES" or "STRUCTURE". Each primary hazard is further detailed into specific scenarios or affected components, such as "MAIN TANK DRY BAY" under "FIRES", or "WING" and "FUSELAGE" under "STRUCTURE". This structure provides a systematic overview of the various aspects to consider when analyzing hazards.

"mermaid
graph TD
    A[ANALYSIS OF HAZARD] --> B[ESSENTIAL SYSTEMS]
    A --> C[FIRES]
    A --> D[LOSS OF THRUST]
    A --> E[STRUCTURE]
    A --> F[OPERATION]

B --> G[HYDRAULICS]
    B --> H[NOSE STEER MAIN BRAKES]
    B --> I[ELECTRICAL POWER]
    B --> J[FLIGHT CONTROLS]
    B --> K[PASS. OXYGEN]

C --> L[MAIN TANK DRY BAY]
    C --> M[FIREX SYSTEM]

L --> N[ABORTED TAKE-OFF]
    L --> O[FUEL FEED SHUT-OFF]
    L --> P[TANK ENTRY]

N --> Q[FUSELAGE ENTRY]
    N --> R[ELECTRICAL WIRING]
    N --> S[HYDRAULIC EQUIPMENT]

D --> T[DAMAGE TO FUEL FEED]
    D --> U[INTER-ENGINE DAMAGE]
    D --> V[DAMAGE TO CONTROLS]
    D --> W[BLEED AIR SYSTEM]

E --> X[WING]
    E --> Y[FUSELAGE]

X --> Z[STRENGTH]
    X --> AA[FLUTTER]

Y --> AB[STRENGTH]
    Y --> AC[DECOMPRESSION]

F --> AD[FLIGHT CREW INCAPACITANCE]
    F --> AE[RANGE]
"](file_tNNDI2wQkpg/image061.png)

EXAMPLE – HAZARD
TREE

FIGURE 1

<table border="1" cellpadding="0" cellspacing="0" width="608">
<tr>
<td valign="top" width="79">
LOC
</td>
<td valign="top" width="143">
COMPONENT
</td>
<td valign="top" width="143">
DAMAGE TO
</td>
<td valign="top" width="143">
SYSTEM LOADED
</td>
<td valign="top" width="100">
DETAIL
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
AILERON
</td>
<td valign="top" width="143">
CABLES/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
AILERON
</td>
<td valign="top" width="143">
CABLES/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#2
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
SPOILER
 - OUTBD MULTI-FUNCTION
</td>
<td valign="top" width="143">
CONTROL/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
SPOILER
 - OUTBD MULTI-FUNCTION
</td>
<td valign="top" width="143">
CONTROL/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
FLAP-OUTBD
</td>
<td valign="top" width="143">
TRACK/SURFACE
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 BUS1
AC
 ESS
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
FLAP-OUTBD
</td>
<td valign="top" width="143">
TRACK/SURFACE
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 BUS1
AC
 ESS
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
RUDDER
</td>
<td valign="top" width="143">
CABLE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1,#2&amp;#3
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
RUDDER
</td>
<td valign="top" width="143">
CABLE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1,#2&amp;#3
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
ELEVATOR
</td>
<td valign="top" width="143">
CABLES
Note
 1
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
ELEVATOR
</td>
<td valign="top" width="143">
CABLES
Note
 1
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#2
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
CHAN1
</td>
<td valign="top" width="143">
PITCH
 TRIM
</td>
<td valign="top" width="143">
CONTROL/POWER
Note
 2
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 BUS1
DC
 BUS1
</td>
</tr>
<tr>
<td valign="top" width="79">
CHAN2
</td>
<td valign="top" width="143">
PITCH
 TRIM
</td>
<td valign="top" width="143">
CONTROL/POWER
Note
 2
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 ESS
DC
 ESS
</td>
</tr>
</table>

FLIGHT CONTROLS – SYSTEM LOADING

Note 1:

Same fragment path must not sever:

ON-SIDE cables + OFF-SIDE hydraulic system +
HYDRAULIC PWR #3

e.g.: Left elevator cable and HYDRAULIC PWR #2 and
#3 or,

Right elevator cable and HYDRAULIC PWR # 1 and # 3

Note 2:

Same fragment path must not sever:

—
Both CHAN1 and CHAN2
circuits

—
ON-SIDE control circuit +
OFF-SIDE power circuit

—
OFF-SIDE control circuit +
ON-SIDE power circuit

EXAMPLE –
SYSTEM LOADING MATRIX

FIGURE 2

![Aviation.Bot AI suggestion, not from EASA source: The image is a technical diagram illustrating the geometric parameters and spatial relationships associated with a tri-sector rotor burst, including various diameters, centroids, and trajectory paths.

Detailed Description:
The diagram, titled "TRI-SECTOR ROTOR BURST" and labeled "FIGURE 3", presents a two-dimensional representation of a rotor and its associated burst characteristics.

At the center of the diagram, there are three concentric circles and one smaller, offset circle.
1. The outermost solid black circle is labeled "Rotor Disk".
2. Inside the "Rotor Disk" is a slightly smaller solid black circle, labeled "Original Diameter".
3. Between the "Original Diameter" and the "Rotor Disk" is a dashed black circle, labeled "Reduced 1/3 Blade Height Diameter".
4. A small dashed black circle, positioned to the right and slightly above the common center of the three larger circles, is labeled "Locus of Centroid". The precise center of this small offset circle is marked with a crosshair and labeled "Sector Centroid".

Originating from the common center of the three larger circles, a 120-degree sector (one-third of a circle) is depicted with a solid black fill. This shaded sector extends outwards to the "Original Diameter" circle.

Two parallel horizontal solid black lines are present, one positioned above and one below the circular arrangement. Both lines are labeled "Limit of swept Path". The upper line is tangent to the top of the "Rotor Disk" circle, and the lower line is tangent to the bottom of the "Rotor Disk" circle.

A horizontal dashed black line extends from the common center of the three larger circles towards the left, labeled "Reference Angle for all Rotors". This line aligns with the lower radial edge of the shaded 120-degree sector.

Below the "Reference Angle for all Rotors" line, another horizontal dashed black line with a left-pointing arrow is labeled "Trajectory". A curved arrow, positioned below the "Trajectory" line and pointing clockwise, indicates "Rotation".

Contextual Linkage:
The diagram visually defines key geometric parameters and spatial relationships crucial for analyzing uncontained engine rotor bursts. The "Rotor Disk" and "Original Diameter" represent the primary dimensions of the rotor. The "Reduced 1/3 Blade Height Diameter" indicates a specific radial dimension relevant to blade height reduction. The shaded "TRI-SECTOR ROTOR BURST" illustrates the angular extent of a fragment release. The "Locus of Centroid" and "Sector Centroid" define the potential path and location of the center of mass for a released fragment. The "Limit of swept Path" establishes the maximum vertical envelope for the rotor's operation or fragment trajectory. The "Trajectory" and "Rotation" arrows, in conjunction with the "Reference Angle for all Rotors", specify the directional aspects of fragment travel and rotor spin.](file_tNNDI2wQkpg/image062.png)

TRI-SECTOR ROTOR
BURST

FIGURE 3

![Aviation.Bot AI suggestion, not from EASA source: A diagram illustrating the typical layout and spatial arrangement of critical aircraft systems and components within the rotor plane cross-section of an aircraft fuselage.

Detailed Description:
The image displays a large, thick black outline of a circular shape, representing an aircraft fuselage cross-section. Inside this circular outline, various aircraft systems and components are depicted using points, lines, and shapes, each accompanied by a text label.

At the top of the circular fuselage outline, two large, solid black circular dots are positioned symmetrically. The left dot is labeled "GEN 1", and the right dot is labeled "GEN 2".

Below "GEN 1" and "GEN 2", two sets of text labels are positioned, with lines extending downwards to specific points within the fuselage:
* On the left, the text "HYDRAULIC SYSTEM NO.1" is displayed, with "[PRESSURE, RETURN]" directly below it. A line connects this text to a point within the fuselage.
* On the right, the text "HYDRAULIC SYSTEM NO.2" is displayed, with "[PRESS., RETURN, BRAKE 2]" directly below it. A line connects this text to a point within the fuselage.

A prominent horizontal thick black line spans across the fuselage, positioned slightly above the center of the circular outline. From the right end of this horizontal line, a dashed line extends outwards to the right, labeled "WL73.5".

Below this horizontal line, numerous smaller circular and rectangular shapes represent various components and lines, each with an associated text label connected by a line.

On the left side, below the horizontal line:
* Two small, hollow white rectangular shapes are positioned side-by-side. Lines point to them from the labels "RUDDER LH 2X" and "ELEVATOR LH 2X".
* Below these rectangles, two small, hollow white circular dots are positioned. Lines point to them from the labels "MOTIVE FLOW" and "FUEL FEED".

In the central-lower part of the fuselage:
* Two small, hollow white circular dots are positioned centrally, with lines pointing to them from the label "APU FUEL PRESS+RETURN".
* A larger, hollow white circular dot is labeled "BLEED AIR 14TH".
* Two solid black circular dots are present, labeled "HYD PUMP 1B" (on the left) and "HYD PUMP 2B" (on the right).
* Below "HYD PUMP 1B", a solid black circular dot is labeled "APU GEN 3".
* To the left of "HYD PUMP 1B", a solid black circular dot is labeled "H-STAB TRIM".
* Below "APU GEN 3", the text "HYDRAULIC SYSTEM NO.3" with "PRESSURE + RETURN" below it, has a line pointing to a small, hollow white circular dot.

On the right side, below the horizontal line:
* Two small, hollow white rectangular shapes are positioned side-by-side. Lines point to them from the labels "RUDDER RH 2X" and "ELEVATOR RH 2X".
* Below these rectangles, two small, hollow white circular dots are positioned. Lines point to them from the labels "MOTIVE FLOW" and "FUEL FEED".
* To the right of "HYD PUMP 2B", a solid black circular dot is labeled "H-STAB TRIM CH1".
* Further to the right and lower, two small, hollow white circular dots are positioned. Lines point to them from the labels "TAIL TANK" and "TRANSFER +" and "REFUEL/DEFUEL".

The lines connecting the text labels to the components indicate the association of the labels with specific points or areas within the fuselage cross-section. The different shapes (solid black circles, hollow white circles, hollow white rectangles) visually differentiate types of components or systems.

Contextual Linkage:
The diagram visually represents the spatial arrangement of critical aircraft systems and components within the rotor plane of an aircraft fuselage. It depicts the location of generators (GEN 1, GEN 2), three distinct hydraulic systems (No. 1, 2, and 3), flight control components (rudder, elevator, horizontal stabilizer trim), fuel system elements (fuel feed lines, APU fuel lines, tail tank connections), bleed air ducts, and hydraulic pumps. The "WL73.5" indicates a specific waterline reference for this cross-section. The "2X" notation for rudder and elevator components (e.g., "RUDDER LH 2X") suggests the presence of multiple instances or redundancy of these components in the depicted location. The labels like "[PRESSURE, RETURN]" for hydraulic systems specify the functional nature of the depicted lines.](file_tNNDI2wQkpg/image063.png)

TYPICAL
LAYOUT OF SYSTEMS IN ROTOR PLANE

FIGURE 4

![Aviation.Bot AI suggestion, not from EASA source: A technical diagram illustrating the concept of trajectory range plotting for uncontained engine fragments, specifically showing how a fragment from the right engine could impact aircraft flight control cables.

Detailed Description:
The image displays a two-dimensional, cross-sectional diagram titled "TRAJECTORY RANGE PLOTTING" with a "VIEW LOOKING FORWARD" perspective indicated by text at the top center.

At the center of the diagram is a large, hollow circle representing an aircraft fuselage or engine casing cross-section. This circle has a vertical dashed centerline extending upwards to the "VIEW LOOKING FORWARD" label and a horizontal dashed centerline passing through its center.

To the top-left of the main central circle, there is a smaller, hollow circle with a crosshair, representing an unspecified component or reference point.

To the top-right of the main central circle, there is another smaller, hollow circle with concentric inner circles and a crosshair, labeled "Rotation" with a clockwise arrow. This represents the right engine, the source of potential fragments.

Two solid lines originate from the center of the right engine circle and extend downwards and to the left, passing through the main central circle. These lines define a sector with angular measurements relative to a horizontal reference from the engine's center. An arc labeled "221°" is shown between the horizontal dashed line and the lower of these two solid lines. Another arc labeled "240°" is shown between the horizontal dashed line and the upper of these two solid lines. Both angles are measured clockwise from the horizontal.

Along the lower circumference of the main central circle, there are four small, solid black circles with internal crosshairs, representing the locations of cable runs within the structure.
* Two circles are positioned on the left side, connected by solid lines to labels "LEFT ELEVATOR CABLES" and "LEFT RUDDER CABLES".
* Two circles are positioned on the right side, connected by solid lines to labels "RIGHT RUDDER CABLES" and "RIGHT ELEVATOR CABLES".

Below the main central circle, two dark, irregularly shaped, solid black areas are depicted, representing cross-sections of cable bundles.
* The area on the right is labeled "A".
* The area on the left is labeled "B".
Solid lines connect the cable run locations on the main circle to these shaded areas.

At the bottom of the image, an "EXAMPLE" text block provides specific context for the diagram:
"EXAMPLE:
The right rudder cables are cut by a 1/3 fan fragment
from the right engine at all trajectory angles between
221° and 240°. Trajectory range A - B is therefore 19°"

Contextual Linkage:
The diagram visually represents the angular range of uncontained engine debris trajectories. The two solid lines originating from the right engine define a "threat window" between 221° and 240°. This angular range, as specified in the example text, is where a 1/3 fan fragment from the right engine could impact and cut the "right rudder cables". The "Trajectory range A - B" refers to the angular spread of this specific fragment path, which is calculated as 19° (240° - 221°), indicating the angular width of the potential damage zone. The diagram illustrates how specific flight control cables (left elevator, left rudder, right rudder, right elevator) are positioned relative to the engine and potential fragment trajectories.](file_tNNDI2wQkpg/image064.png)

TRAJECTORY
RANGE PLOTTING

FIGURE 5

![Aviation.Bot AI suggestion, not from EASA source: **Overall Summary:** The image is a technical diagram illustrating a "TRAJECTORY RANGE PLOTTING" concept, depicting the geometric relationships between a central target, two reference points (N1 and N2) with associated radii, and the swept path of a "locus of centroid" related to potential trajectories.

**Detailed Description:** The diagram is presented on a white background with all elements drawn in black. At the approximate center of the lower half of the image, there is a horizontally oriented, solid black rectangular box labeled "TARGET" in uppercase, bold text.

Two circles are positioned relative to the "TARGET":
1.  A circle labeled "N1" is located to the bottom right of the "TARGET". Inside this circle, a short solid line extends from its center to its circumference, forming a right angle with a longer solid line that is tangent to the circle. This short line is labeled "1R".
2.  A circle labeled "N2" is located to the top left of the "TARGET". Similar to N1, a short solid line extends from its center to its circumference, forming a right angle with a longer solid line that is tangent to the circle. This short line is also labeled "1R".

Several solid black lines represent trajectories or reference paths:
*   Two lines, labeled "T 1", originate from the bottom left and bottom right corners of the "TARGET" rectangle, respectively. Both lines extend downwards and outwards, passing tangent to the "N1" circle.
*   Two lines, labeled "T 2", originate from the top left and top right corners of the "TARGET" rectangle, respectively. Both lines extend upwards and outwards, passing tangent to the "N2" circle.
*   Two additional solid lines extend from the top left and top right corners of the "TARGET" rectangle upwards and rightwards, converging at a point. An arc connects these two lines near their origin at the "TARGET", indicating an angle.

In the upper right portion of the diagram, there is a section related to a "LOCUS OF CENTROID":
*   A dashed circle is present, with a solid black arrow pointing to its center from the text "LOCUS OF CENTROID".
*   Inside this dashed circle, a solid black, V-shaped figure is depicted, with its apex pointing downwards. The upper ends of this V-shape extend slightly beyond the dashed circle's circumference.
*   Two solid lines extend downwards from the upper ends of this V-shaped figure, converging at the same point where the two lines from the "TARGET" (mentioned above) also converge.
*   An arc is drawn between these two converging lines, indicating an angle.
*   Above the "LOCUS OF CENTROID" area, a measurement labeled "SWEPT PATH 2R" is indicated. This label is positioned above a horizontal double-headed arrow. Two vertical dashed lines extend downwards from the ends of this arrow, aligning with the outermost horizontal points of the V-shaped figure within the dashed circle, indicating the width of the "SWEPT PATH 2R".

**Contextual Linkage:** This diagram, identified as "FIGURE 5" in the surrounding text, visually represents "TRAJECTORY RANGE PLOTTING". The "TARGET" likely signifies a critical component or area on an aircraft. The lines labeled "T 1" and "T 2" represent different trajectory boundaries or paths originating from the target. The circles "N1" and "N2" with their "1R" radii likely define reference points or zones for these trajectories. The "LOCUS OF CENTROID" and its associated "SWEPT PATH 2R" illustrate the potential area or envelope that a moving object (e.g., uncontained engine debris) might occupy or traverse, with 'R' likely representing a characteristic radius related to the debris or engine component. The angles indicated by arcs suggest the angular spread of these trajectories.](file_tNNDI2wQkpg/image065.png)

TYPICAL
TRAJECTORY PLOTTING

FIGURE 6

![Aviation.Bot AI suggestion, not from EASA source: The image illustrates two distinct three-dimensional diagrams defining angular parameters, specifically translational and spread angles, relevant to fragment trajectories and their interaction with a target.

Detailed Description:
The image presents two separate 3D perspective diagrams, arranged vertically.

The **upper diagram** depicts a "TARGET" represented as a rectangular block with two circular openings on its front face, positioned on the left side of the diagram. A curved line labeled "FRAGMENT SWEPT PATH" with an arrow indicates a trajectory originating from the left and sweeping towards the right, passing near the target. Below this label, text states "SEE FIGURE 6 FOR DETAILS", with an arrow pointing to the target block. A large, tilted elliptical shape, labeled "PLANE OF ROTATION", is shown on the right, with its center aligned with the origin of a coordinate system indicated by dashed lines. A shaded, fan-shaped region, originating from the center of the "PLANE OF ROTATION" and extending towards the "TARGET", represents a cone. An angle labeled "Φ2 - Φ1" is marked within this shaded region, near its apex. Two labels, "TRANSLATIONAL RELEASE ANGLE" and "TRANSLATIONAL RISK ANGLE", are positioned above and to the right of the elliptical "PLANE OF ROTATION", with arrows pointing to its outer boundary.

The **lower diagram** is positioned below the upper one and depicts a similar "TARGET" rectangular block with two circular openings on its front face, also on the left. A flat, square plane, labeled "PLANE NORMAL TO PLANE OF ROTATION", is shown on the right, with its center aligned with the origin of a coordinate system indicated by dashed lines. This plane is oriented perpendicularly to the implied axis of rotation from the upper diagram. A shaded, fan-shaped region, originating from the center of the "PLANE NORMAL TO PLANE OF ROTATION" and extending towards the "TARGET", represents a cone. An angle labeled "Ψ2 - Ψ1" is marked within this shaded region, near its apex. A label "SPREAD ANGLE" points with an arrow to the shaded cone near the target. Another label, "SPREAD RISK ANGLE", points with an arrow to the outer boundary of the shaded cone, also near the target.

Contextual Linkage:
The two diagrams define different angular aspects of fragment trajectories relative to a target. The upper diagram illustrates angles within the "PLANE OF ROTATION", specifically the "TRANSLATIONAL RELEASE ANGLE" and "TRANSLATIONAL RISK ANGLE", and the angular range "Φ2 - Φ1" associated with the fragment's path towards the target. The lower diagram illustrates angles perpendicular to the plane of rotation, defining the "SPREAD ANGLE" and "SPREAD RISK ANGLE", and the angular range "Ψ2 - Ψ1" for the fragment's spread as it approaches the target. The "FRAGMENT SWEPT PATH" in the upper diagram is explicitly linked to "FIGURE 6 FOR DETAILS", suggesting a continuation or elaboration of this concept in another figure. Both diagrams use a "TARGET" block to represent the object or area susceptible to fragment impact.](file_tNNDI2wQkpg/image066.png)

DEFINITION -
THREAT WINDOW

FIGURE 7

![Aviation.Bot AI suggestion, not from EASA source: This image presents a sample rotor stage plotting chart, titled "ENGINE ROTOR FAILURE - SYSTEM EFFECTS," which visually maps the impact of uncontained engine rotor failure debris on various aircraft systems and components across a range of trajectory angles.

Detailed Description:
The image is a detailed grid-based chart, primarily black and white, with a title at the top and a legend at the bottom.

At the very top, the main title "ENGINE ROTOR FAILURE - SYSTEM EFFECTS" is centered.
Below this, to the left, are labels indicating the context of the analysis: "ENGINE: RIGHT", "COMPONENT: H.P. TURBINE 1", and "SIZE: in." followed by a blank space.

The main body of the image is a large table or grid. The table has a primary header row that spans across the top, containing "H.P. TURBINE 1" (centered above the "IN" and "OUT" columns) and "TRAJECTORY ANGLES IN DEGREES" (centered above the angle columns).

The second header row defines the columns for the data:
*   The first column is unlabeled but contains broad system categories.
*   The second column is labeled "COMPONENT".
*   The third column is labeled "DETAIL".
*   The fourth column is unlabeled but contains single letters (L, R, A, B) or numbers (1, 2).
*   The fifth column is labeled "IN".
*   The sixth column is labeled "OUT".
*   The subsequent columns, from the seventh to the last, are labeled with specific "TRAJECTORY ANGLES IN DEGREES": 210, 215, 220, 228, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315.

The first column on the left lists major aircraft system categories, each spanning multiple rows:
*   FLIGHT CONTROLS (spans 6 rows)
*   HYDRAULIC POWER (spans 9 rows)
*   FIRE PROTECTION (spans 3 rows)
*   FUEL (spans 5 rows)
*   ELECTRICAL POWER (spans 6 rows)
*   ENVIRONMENTAL (spans 8 rows)
*   POWER PLANT (spans 2 rows)
*   APU (spans 1 row)

Each row within these categories details a specific component or sub-system, its detail/type, an identifier (L/R/A/B/number), and "IN" and "OUT" angle values. The remaining cells in each row, corresponding to the "TRAJECTORY ANGLES IN DEGREES," contain visual representations of impact.

The content of the plotting cells (trajectory angles) includes:
*   **Solid black rectangles:** These represent a "DIRECT HIT" as per the legend. They appear as continuous horizontal bars across specific angle ranges.
*   **"OOOOO" character sequences:** These represent "OPPOSITE ENGINE FUEL LINE" as per the legend. They appear as continuous horizontal sequences of 'O' characters across specific angle ranges.
*   **"XXXXX" character sequences:** These represent "OPPOSITE GENERATOR" as per the legend. They appear as continuous horizontal sequences of 'X' characters across specific angle ranges.
*   Blank cells: Indicate no impact for that angle range.

Specific data points and their plotted impacts are as follows:](file_tNNDI2wQkpg/image067.png)

Appendix 1 to AMC 20-128A User’s Manual

ED Decision 2003/12/RM

RISK ANALYSIS METHODOLOGY for
UNCONTAINED ENGINE/APU FAILURE

INDEX

1.0       GENERAL

2.0       SCOPE

3.0       FUNDAMENTAL
COMPONENTS OF A SAFETY AND RISK ANALYSIS

4.0       ASSUMPTIONS

5.0       PLOTTING

6.0       METHODOLOGY
– PROBABILITY ASSESSMENT

7.0       RESULTS
ASSESSMENT

<table border="0" cellpadding="0" cellspacing="0" width="591">
<tr>
<td valign="top" width="72">
FIGURE 1
</td>
<td valign="top" width="519">
EXAMPLE – HAZARD TREE
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 2
</td>
<td valign="top" width="519">
EXAMPLE – SYSTEM LOADING MATRIX
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 3
</td>
<td valign="top" width="519">
TRI-SECTOR ROTOR BURST
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 4
</td>
<td valign="top" width="519">
TYPICAL LAYOUT OF SYSTEMS IN ROTOR
 PLANE
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 5
</td>
<td valign="top" width="519">
TRAJECTORY RANGE PLOTTING
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 6
</td>
<td valign="top" width="519">
TYPICAL TRAJECTORY PLOTTING
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 7
</td>
<td valign="top" width="519">
DEFINITION – THREAT WINDOW
</td>
</tr>
<tr>
<td valign="top" width="72">
FIGURE 8
</td>
<td valign="top" width="519">
SAMPLE ROTOR STAGE PLOTTING CHART
</td>
</tr>
</table>

1.0       GENERAL

1.1       The
design of aeroplane and engine systems and the location of the engines
relative to critical systems and structure have a significant impact on
survivability of the aeroplane following an uncontained engine failure. CS
23.903(b)(1) and 25.903(d)(1) of the EASA Certification Specifications (CS)
require that design precautions be taken to minimise the hazard to the
aeroplane due to uncontained failures of engine or auxiliary power unit (APU).
[AMC 20-128A](#_DxCrossRefBm421436885) provides guidance for
demonstrating compliance with these requirements.

1.2       As
a part of this compliance demonstration, it is necessary to quantitatively
assess the risk of a catastrophic failure in the event of an uncontained
engine failure. This User’s Manual describes an acceptable method for this
purpose.

1.3       The
objective of the risk analysis is to measure the remaining risk after prudent
and practical design considerations have been taken. Since each aeroplane
would have unique features which must be considered when applying the methods
described in this manual, there should be some flexibility in the methods and
procedures.

1.4       It
is a preferred approach to use these methods throughout the development of an
aeroplane design to identify problem areas at an early stage when appropriate
design changes are least disruptive. It is also advisable to involve the
European Aviation Safety Agency (EASA) in this process at an early stage when
appropriate interpretation of the methodology and documentation requirements
can be established.

1.5       It
should be noted that although the risk analysis produces quantitative results,
subjective assessments are inherent in the methods of the analysis regarding
the criticality of specific types of aeroplane component failures. Assumptions
for such assessments should be documented along with the numerical results.

1.6       Aeroplane
manufacturers have each developed their own method of assessing the effects of
rotor failure, as there are many ways to get to the same result. This User’s
Manual identifies all the elements that should be contained in an analysis, so
that it can be interpreted by a person not familiar with such a process.

1.7       The
intent of this manual therefore is to aid in establishing how an analysis is
prepared, without precluding any technological advances or existing
proprietary processes.

1.8       AMC
20-128A makes allowance for the broad configuration of the aeroplane as such
damage to the structure due to rotor failure generally allows for little
flexibility in design. System lay-out within a rotor burst zone, however, can
be optimized.

1.9       Damage
to structure, which may involve stress analysis, generally can be analyzed
separately, and later coordinated with simultaneous system effects.

1.10    For
an analysis of the effects on systems due to a rotor failure the aeroplane
must be evaluated as a whole; and a risk analysis must specifically highlight
all critical cases identified which have any potential to result in a
catastrophe.

1.11    Such
an analysis can then be used to establish that reasonable precautions have
been taken to minimise the hazards, and that the remaining hazards are an
acceptable risk.

1.12    A
safety and a risk analysis are interdependent, as the risk analysis must be
based on the safety analysis.

The safety analysis therefore is the
starting point that identifies potential hazardous or catastrophic effects
from a rotor failure and is the basic tool to minimise the hazard in
accordance with the guidelines of [AMC 20-128A](#_DxCrossRefBm421436885).

1.13    The
risk analysis subsequently assesses and quantifies the residual risk to the
aeroplane.

2.0       SCOPE

The following describes the scope of
analyses required to assess the aeroplane risk levels against the criteria set
forth in Paragraph 10 of [AMC 20-128A](#_DxCrossRefBm421436885).

2.1       Safety

Analysis is required to identify the
critical hazards that may be numerically analyzed (hazards remaining after all
practical design precautions have been taken).

Functional criticality will vary by
aeroplane and may vary by flight phase.

Thorough understanding of each aeroplane
structure and system functions is required to establish the criticality
relative to each fragment trajectory path of the theoretical failure.

Assistance from experts within each
discipline is typically required to assure accuracy of the analysis in such
areas as effects of fuel tank penetration on leakage paths and ignition
hazards, thrust level control (for loss of thrust assessment), structural
capabilities (for fuselage impact assessment), aeroplane controllability (for
control cables impact assessment), and fuel asymmetry.

2.2       Risk

For each remaining critical hazard, the
following assessments may be prepared using the engine/APU failure models as
defined in Paragraph 9 of [AMC 20-128A](#_DxCrossRefBm421436885):

a.         Flight
mean risk for single 1/3 disc fragment.

b.        Flight
mean risk for single intermediate fragment.

c.         Flight
mean risk for alternate model (when used as an alternate to the 1/3 disc
fragment and intermediate fragment).

d.        Multiple
1/3 disc fragments for duplicated or multiplicated systems.

e.        Specific
risk for single 1/3 disc fragment and single intermediate fragment.

f.         Specific
risk for any single disc fragment that may result in catastrophic structural
damage.

The risk level criteria for each failure
model are defined in Paragraph 10 of [AMC 20-128A](#_DxCrossRefBm421436885).

3.0       FUNDAMENTAL
COMPONENTS OF A SAFETY AND RISK ANALYSIS

3.1       The
logical steps for a complete analysis are:

b.        Establish
a Functional Hazard Tree (see Figure 1), or a System Matrix (see Figure 2)
that identifies all system interdependencies and failure combinations that
must be avoided (if possible) when locating equipment in the rotor burst
impact area.

In theory, if this is carried out to the
maximum, no critical system hazards other than opposite engine or fuel line
hits would exist.

c.         Establish
the fragment trajectories and trajectory ranges both for translational and
spread risk angles for each damage. Plot these on a chart or graph, and identify
the trajectory ranges that could result in hazardous combinations (threats) as
per the above system matrix or functional hazard analysis.

d.        Apply
risk factors, such as phase of flight or other, to these threats, and
calculate the risk for each threat for each rotor stage.

e.        Tabulate,
summarize and average all cases.

3.2       In
accordance with [AMC 20-128A](#_DxCrossRefBm421436885) the
risk to the aeroplane due to uncontained rotor failure is assessed to the
effects, once such a failure has occurred.

The probability of occurrence of rotor
failure, as analyzed with the probability methods of AMC 25.1309 (i.e.
probability as a function of critical uncontained rotor failure rate and
exposure time), does not apply.

3.3       The
total risk level to the aeroplane, as identified by the risk analysis, is the
mean value obtained by averaging the values of all rotor stages of all engines
of the aeroplane, expressed as Flight Mean Risk.

4.0       ASSUMPTIONS

4.1       The
following conservative assumptions, in addition to those in Paragraphs
10(a)(1), (2) and (3) of [AMC 20-128A](#_DxCrossRefBm421436885),
have been made in some previous analyses. However, each aeroplane design may
have unique characteristics and therefore a unique basis for the safety
assessment leading to the possibility of different assumptions. All
assumptions should be substantiated within the analysis:

a.         The
1/3 disc fragment as modeled in Paragraph 9(a) of the [AMC 20-128A](#_DxCrossRefBm421436885) travels along a trajectory
path that is tangential to the sector centroid locus, in the direction of
rotor rotation (Refer to Figure 3).

The sector fragment rotates about its
centroid without tumbling and sweeps a path equal to twice the greatest radius
that can be struck from the sector centroid that intersects its periphery.

The fragment is considered to possess
infinite energy, and therefore to be capable of severing lines, wiring, cables
and unprotected structure in its path, and to be undeflected from its original
trajectory unless deflection shields are fitted. However, protective shielding
or an engine being impacted may be assumed to have sufficient mass to stop
even the most energetic fragment.

b.        The
probability of release of debris within the maximum spread angle is uniformly
distributed over all directions.

c.         The
effects of severed electrical wiring are dependent on the configuration of the
affected system. In general, severed wiring is assumed to not receive
inadvertent positive voltage for any significant duration.

d.        Control
cables that are struck by a fragment disconnect.

e.        Hydraulically
actuated, cable driven control surfaces, which do not have designated “fail
to” settings, tend to fail to null when control cables are severed. Subsequent
surface float is progressive and predictable.

f.         Systems
components are considered unserviceable if their envelope has been touched. In
case of an engine being impacted, the nacelle structure may be regarded as
engine envelope, unless damage is not likely to be hazardous.

g.         Uncontained
events involving in-flight penetration of fuel tanks will not result in fuel
tank explosion.

h.        Unpowered
flight and off-airport landings, including ditching, may be assumed to be not
catastrophic to the extent validated by accident statistics or other accepted
factors.

i.          Damage
to structure essential for completion of flight is catastrophic (Ref. [AMC 20-128A](#_DxCrossRefBm421436885), Paragraph 10.b(1)).

j.          The
flight begins when engine power is advanced for takeoff and ends after landing
when turning off the runway.

5.0       PLOTTING

5.1       Cross-section
and plan view layouts of the aeroplane systems in the ranges of the rotor
burst impact areas should be prepared, either as drawings, or as computer
models

These layouts should plot the precise
location of the critical system components, including fuel and hydraulic
lines, flight control cables, electric wiring harnesses and junction boxes,
pneumatic and environmental system ducting, fire extinguishing; critical
structure, etc.

5.2       For
every rotor stage a plane is developed. Each of these planes contains a view
of all the system components respective outer envelopes, which is then used to
generate a cross-section. See Figure 4.

5.3       Models
or drawings representing the various engine rotor stages and their fore and
aft deviation are then generated.

5.4       The
various trajectory paths generated for each engine rotor stage are then
superimposed on the cross-section layouts of the station planes that are in
the range of that potential rotor burst in order to study the effects (see
Figure 5). Thus separate plots are generated for each engine rotor stage or
rotor group.

To reduce the amount of an analysis the
engine rotor stages may also be considered as groups, as applicable for the
engine type, using the largest rotor stage diameter of the group.

5.5       These
trajectory paths may be generated as follows and as shown in Figure 6:

a.         Two
tangent lines T1 are drawn between the locus of the centroid and the target
envelope.

b.        At
the tangent line touch points, lines N1 and N2 normal to the tangent lines,
are drawn with the length equal to the radius of the fragment swept path (as
also shown in Figure 1).

c.         Tangent
lines T2 are drawn between the terminal point of the normal lines and the
locus of the centroid. The angle between these two tangent lines is the
translational risk angle.

5.6       The
entry and exit angles are then calculated.

5.7       The
initial angle of intersection and the final angle of intersection are
recorded, and the trajectories in between are considered to be the range of
trajectories in which this particular part would be impacted by a rotor
sector, and destroyed (i.e. the impact area).

The intersections thus recorded are then
entered on charts in tabular form so that the simultaneous effects can be
studied. Refer to Figure 8.

Thus it will be seen that the total systems’
effects can be determined and the worst cases identified.

5.9
If a potentially serious multiple system damage case is identified, then a
more detailed analysis of the trajectory range will be carried out by breaking
the failure case down into the specific fore-aft spread angle, using the
individual rotor stage width instead of combined groups, if applicable.

6.0       METHODOLOGY
– PROBABILITY ASSESSMENT

6.1       Those
rotor burst cases that have some potential of causing a catastrophe are
evaluated in the analysis in an attempt to quantify an actual probability of a
catastrophe, which will, in all cases, depend on the following factors:

a.         The
location of the engine that is the origin of the fragment, and its direction
of rotation.

b.        The
location of critical systems and critical structure.

c.         The
rotor stage and the fragment model.

d.        The
translational trajectory of the rotor fragment,

e.        The
specific spread angle range of the fragment.

f.         The
specific phase of the flight at which the failure occurs.

g.         The
specific risk factor associated with any particular loss of function.

6.2       Engine
Location

The analysis should address the effects on
systems during one flight after a single rotor burst has occurred, with a
probability of 1.0. As the cause may be any one of the engines, the risk from
each engine is later averaged for the number of engines.

The analysis trajectory charts will then
clearly show that certain system damage is unique to rotor fragments from a
particular engine due to the direction of rotation, or, that for similar
system damage the trajectory range varies considerably between engines.

A risk summary should table each engine case
separately with the engine location included.

6.3       Rotor
Element

The probability of rotor failure is assumed
to be 1.0 for each of all rotor stages. For the analysis the individual
risk(s) from each rotor stage of the engine should be assessed and tabled.

6.4       Translational
Risk Angle

The number of degrees of included arc (out
of 360) at which a fragment intersects the component/structure being analyzed.
Refer to Figure 6 and Figure 7.

6.5       Trajectory
Probability (P)

The probability of a liberated rotor
fragment leaving the engine case is equal over 360, thus the probability P of
that fragment hitting a system component is the identified Translational Risk
Angle ɸ in degrees °, divided by 360, i.e.

![Aviation.Bot AI suggestion, not from EASA source: P = φ / 360](/static/files/file_wSyEACTCE2d/image047.png)

![Aviation.Bot AI suggestion, not from EASA source: \[\frac{\phi 1 - \phi 2}{360}\]](/static/files/file_wSyEACTCE2d/image048.png)

6.6       Spread
Angle

If the failure model of the analysis assumes
a (fore and aft) spread of ± 5°, then the spread angle is a total of 10°. If a
critical component can only be hit at a limited position within that spread,
then the exposure of that critical component can then be factored according to
the longitudinal position within the spread angle, e.g.:

![Aviation.Bot AI suggestion, not from EASA source: \[\frac{\psi 2 - \psi 1}{\textit{spread angle}}\]](/static/files/file_wSyEACTCE2d/image049.png)

If a component can only be hit at the
extreme forward range of +4° to +5°, then the factor is .1 (for one degree out
of 10).

6.7       Threat
Window

The definition of a typical threat window is
shown in Figure 7.

6.8       Phase
of Flight

Certain types of system damage may be
catastrophic only during a specific portion of the flight profile, such as a
strike on the opposite engine during take-off after V1 (i.e. a probability of
1.0), while with altitude a straight-ahead landing may be possible under
certain favourable conditions (e.g. a probability of less than 1.0). The
specific case can then be factored accordingly.

6.8.1   The
most likely time for an uncontained rotor failure to occur is during take-off,
when the engine is under highest stress. Using the industry accepted standards
for the percentage of engine failures occurring within each flight phase, the
following probabilities are assumed:

<table border="1" cellpadding="0" cellspacing="0" width="491">
<tr>
<td valign="top" width="245">
Take-off
 before V1
</td>
<td valign="top" width="245">
35%
</td>
</tr>
<tr>
<td valign="top" width="245">
V1
 to first power reduction
</td>
<td valign="top" width="245">
20%
</td>
</tr>
<tr>
<td valign="top" width="245">
Climb
</td>
<td valign="top" width="245">
22%
</td>
</tr>
<tr>
<td valign="top" width="245">
Cruise
</td>
<td valign="top" width="245">
14%
</td>
</tr>
<tr>
<td valign="top" width="245">
Descent
</td>
<td valign="top" width="245">
3%
</td>
</tr>
<tr>
<td valign="top" width="245">
Approach
</td>
<td valign="top" width="245">
2%
</td>
</tr>
<tr>
<td valign="top" width="245">
Landing/Reverse
</td>
<td valign="top" width="245">
4%
</td>
</tr>
</table>

6.8.2   The
flight phase failure distribution above is used in the calculations of
catastrophic risk for all cases where this risk varies with flight phase.

![Aviation.Bot AI suggestion, not from EASA source: Dp = \frac{P_{flight\ phase}\ \%}{100}](/static/files/file_wSyEACTCE2d/image050.png)

6.9       Other
Risk Factors

Risks such as fire, loss of pressurization,
etc., are individually assessed for each case where applicable, using
conservative engineering judgment. This may lead to a probability of
catastrophe (i.e., risk factor) smaller than 1.0.

6.9.1   The
above probabilities and factors are used in conjunction with the critical
trajectory range defined to produce a probability of the specific event
occurring from any random rotor burst.

This value is then factored by the
"risk" factor assessed for the case, to derive a calculated
probability of catastrophe for each specific case.

Typical conditional probability values for
total loss of thrust causing catastrophic consequences are:

<table border="1" cellpadding="0" cellspacing="0" width="489">
<tr>
<td valign="top" width="264">
Phase
</td>
<td valign="top" width="112">
Dp
</td>
<td valign="top" width="112">
Risk
</td>
</tr>
<tr>
<td valign="top" width="264">
T.O.–V1
 to first power reduction
</td>
<td valign="top" width="112">
0.20
</td>
<td valign="top" width="112">
1.0
</td>
</tr>
<tr>
<td valign="top" width="264">
Climb
</td>
<td valign="top" width="112">
0.22
</td>
<td valign="top" width="112">
0.4
</td>
</tr>
<tr>
<td valign="top" width="264">
Cruise
</td>
<td valign="top" width="112">
0.14
</td>
<td valign="top" width="112">
0.2
</td>
</tr>
<tr>
<td valign="top" width="264">
Descent
</td>
<td valign="top" width="112">
0.03
</td>
<td valign="top" width="112">
0.4
</td>
</tr>
<tr>
<td valign="top" width="264">
Approach
</td>
<td valign="top" width="112">
0.02
</td>
<td valign="top" width="112">
0.4
</td>
</tr>
</table>

6.10    All
individual case probabilities are then tabled and summarised.

6.11    The
flight mean values are obtained by averaging those for all discs or rotor
stages on all engines across a nominal flight profile.

The following process may be used to
calculate the flight mean value for each Failure Model:

a.         Establish
from the table in Figure 8 the threat windows where, due to combination of
individual damages, a catastrophic risk exists.

b.        For
each stage case calculate the risk for all Critical Hazards

c.         For
each stage case apply all risk factors, and, if applicable, factor for Flight
Phase-Failure distribution

d.        For
each engine, average all stages over the total number of engine stages

e.        For
each aeroplane, average all engines over the number of engines.

7.0       RESULTS
ASSESSMENT

7.1       An
applicant may show compliance with CS 23.903(b)(1) and CS 25.903(d)(1) using
guidelines set forth in [AMC 20-128A](#_DxCrossRefBm421436885).
The criteria contained in the AMC may be used to show that:

a.         Practical
design precautions have been taken to minimise the damage that can be caused
by uncontained engine debris, and

b.        Acceptable
risk levels, as specified in [AMC 20-128A](#_DxCrossRefBm421436885),
Paragraph 10, have been achieved for each critical Failure Model.

7.2       The
summary of the applicable risk level criteria is shown in Table 1 below.

Table
1 Summary of Acceptable Risk Level Criteria

<table border="1" cellpadding="0" cellspacing="0" width="533">
<tr>
<td valign="top" width="291">
Requirement
</td>
<td valign="top" width="242">
Criteria
</td>
</tr>
<tr>
<td valign="top" width="291">
Average 1/3 Disc Fragment
</td>
<td valign="top" width="242">
1 in 20
</td>
</tr>
<tr>
<td valign="top" width="291">
Average Intermediate Fragment
</td>
<td valign="top" width="242">
1 in 40
</td>
</tr>
<tr>
<td valign="top" width="291">
Average Alternate Model
</td>
<td valign="top" width="242">
1 in 20 @ ± 5 degree Spread Angle
</td>
</tr>
<tr>
<td valign="top" width="291">
Multiple Disc Fragments
</td>
<td valign="top" width="242">
1 in 10
</td>
</tr>
<tr>
<td valign="top" width="291">
Any single fragment (except for structural damage)
</td>
<td valign="top" width="242">
2 x corresponding average criterion
</td>
</tr>
</table>

![Aviation.Bot AI suggestion, not from EASA source: A flowchart illustrating the hierarchical breakdown of potential hazards in an aviation context, categorizing them into "Essential Systems", "Fires", "Loss of Thrust", "Structure", and "Operation", and further detailing their sub-components and associated risks.

Detailed Description:
The image displays a black and white flowchart with a top-level rectangular box labeled "ANALYSIS OF HAZARD". From this top box, a single vertical line descends and branches horizontally to connect to five rectangular boxes on the second level: "ESSENTIAL SYSTEMS", "FIRES", "LOSS OF THRUST", "STRUCTURE", and "OPERATION". All boxes are white with black borders and black text. All connecting lines are solid black.

**Branch 1: "ESSENTIAL SYSTEMS"**
A vertical line descends from the "ESSENTIAL SYSTEMS" box to a horizontal line. From this horizontal line, five vertical lines descend to five rectangular boxes on the lowest level of this branch: "HYDRAULICS", "NOSE STEER MAIN BRAKES", "ELECTRICAL POWER", "FLIGHT CONTROLS", and "PASS. OXYGEN".

**Branch 2: "FIRES"**
A vertical line descends from the "FIRES" box and branches horizontally to connect to two rectangular boxes: "MAIN TANK DRY BAY" and "FIREX SYSTEM".
From the "FIREX SYSTEM" box, a vertical line descends to a horizontal line. From this horizontal line, three vertical lines descend to three rectangular boxes: "ABORTED TAKE-OFF", "FUEL FEED SHUT-OFF", and "TANK ENTRY".
Below these three boxes ("ABORTED TAKE-OFF", "FUEL FEED SHUT-OFF", and "TANK ENTRY"), a horizontal line connects their bottom edges. From this horizontal line, three vertical lines descend to three rectangular boxes: "FUSELAGE ENTRY", "ELECTRICAL WIRING", and "HYDRAULIC EQUIPMENT".

**Branch 3: "LOSS OF THRUST"**
A vertical line descends from the "LOSS OF THRUST" box to a horizontal line. From this horizontal line, four vertical lines descend to four rectangular boxes: "DAMAGE TO FUEL FEED", "INTER-ENGINE DAMAGE", "DAMAGE TO CONTROLS", and "BLEED AIR SYSTEM".

**Branch 4: "STRUCTURE"**
A vertical line descends from the "STRUCTURE" box and branches horizontally to connect to three rectangular boxes: "FLIGHT CREW INCAPACITANCE", "WING", and "FUSELAGE".
From the "WING" box, a vertical line descends to a horizontal line. From this horizontal line, two vertical lines descend to two rectangular boxes: "STRENGTH" and "FLUTTER".
From the "FUSELAGE" box, a vertical line descends to a horizontal line. From this horizontal line, two vertical lines descend to two rectangular boxes: "STRENGTH" and "DECOMPRESSION".

**Branch 5: "OPERATION"**
A vertical line descends from the "OPERATION" box and connects to the "FLIGHT CREW INCAPACITANCE" box, which is also connected to the "STRUCTURE" box.
From the "FLIGHT CREW INCAPACITANCE" box, a vertical line descends to a horizontal line. From this horizontal line, a single vertical line descends to a rectangular box labeled "RANGE".

Contextual Linkage:
The flowchart visually represents a hierarchical decomposition of potential hazards, starting from a general "ANALYSIS OF HAZARD" and breaking it down into specific areas of concern such as system failures, fire-related events, thrust loss scenarios, structural integrity issues, and operational impacts. The connections indicate a parent-child relationship or a contributing factor relationship, where higher-level categories encompass the more specific hazards listed below them. For instance, "FIRES" can lead to issues like "MAIN TANK DRY BAY" or "FIREX SYSTEM" problems, which in turn can lead to "ABORTED TAKE-OFF" scenarios, and ultimately to damage like "FUSELAGE ENTRY" or "ELECTRICAL WIRING" damage. Similarly, "STRUCTURE" hazards are broken down into "WING" and "FUSELAGE" issues, each with specific concerns like "STRENGTH" or "FLUTTER" for the wing, and "STRENGTH" or "DECOMPRESSION" for the fuselage. "FLIGHT CREW INCAPACITANCE" and "RANGE" are identified as hazards under both "STRUCTURE" and "OPERATION".](file_wSyEACTCE2d/image051.png)

EXAMPLE
– HAZARD TREE

FIGURE
1

<table border="1" cellpadding="0" cellspacing="0" width="608">
<tr>
<td valign="top" width="79">
LOC
</td>
<td valign="top" width="143">
COMPONENT
</td>
<td valign="top" width="143">
DAMAGE
 TO
</td>
<td valign="top" width="143">
SYSTEM
 LOADED
</td>
<td valign="top" width="100">
DETAIL
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
AILERON
</td>
<td valign="top" width="143">
CABLES/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
AILERON
</td>
<td valign="top" width="143">
CABLES/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#2
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
SPOILER
 - OUTBD MULTI-FUNCTION
</td>
<td valign="top" width="143">
CONTROL/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
SPOILER
 - OUTBD MULTI-FUNCTION
</td>
<td valign="top" width="143">
CONTROL/SURFACE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
FLAP-OUTBD
</td>
<td valign="top" width="143">
TRACK/SURFACE
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 BUS1
AC
 ESS
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
FLAP-OUTBD
</td>
<td valign="top" width="143">
TRACK/SURFACE
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 BUS1
AC
 ESS
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
RUDDER
</td>
<td valign="top" width="143">
CABLE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1,#2&amp;#3
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
RUDDER
</td>
<td valign="top" width="143">
CABLE
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1,#2&amp;#3
</td>
</tr>
<tr>
<td valign="top" width="79">
LEFT
</td>
<td valign="top" width="143">
ELEVATOR
</td>
<td valign="top" width="143">
CABLES
Note
 1
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#1
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
RIGHT
</td>
<td valign="top" width="143">
ELEVATOR
</td>
<td valign="top" width="143">
CABLES
Note
 1
</td>
<td valign="top" width="143">
HYDRAULIC
 POWER
</td>
<td valign="top" width="100">
#2
 &amp; #3
</td>
</tr>
<tr>
<td valign="top" width="79">
CHAN1
</td>
<td valign="top" width="143">
PITCH
 TRIM
</td>
<td valign="top" width="143">
CONTROL/POWER
Note
 2
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 BUS1
DC
 BUS1
</td>
</tr>
<tr>
<td valign="top" width="79">
CHAN2
</td>
<td valign="top" width="143">
PITCH
 TRIM
</td>
<td valign="top" width="143">
CONTROL/POWER
Note
 2
</td>
<td valign="top" width="143">
ELECTRICAL
 POWER
</td>
<td valign="top" width="100">
AC
 ESS
DC
 ESS
</td>
</tr>
</table>

FLIGHT CONTROLS – SYSTEM LOADING

Note 1:

Same fragment path must not sever:

ON-SIDE cables + OFF-SIDE hydraulic system +
HYDRAULIC PWR #3

e.g.: Left elevator cable and HYDRAULIC PWR #2 and
#3 or,

Right elevator cable and HYDRAULIC PWR # 1 and # 3

Note 2:

Same fragment path must not sever:

—
Both CHAN1 and CHAN2
circuits

—
ON-SIDE control circuit +
OFF-SIDE power circuit

—
OFF-SIDE control circuit +
ON-SIDE power circuit

EXAMPLE
– SYSTEM LOADING MATRIX

FIGURE
2

![Aviation.Bot AI suggestion, not from EASA source: The image illustrates the geometric representation of a tri-sector rotor burst, defining key parameters such as rotor disk dimensions, swept path limits, and the trajectory of a fragment.

Detailed Description:
The image displays a two-dimensional diagram centered around a series of concentric circles and arcs, representing an engine rotor.
1.  **Rotor Disk:** The outermost solid black circle is labeled "Rotor Disk" with a black arrow pointing from the label to its circumference.
2.  **Original Diameter:** Inside the "Rotor Disk," a dashed black circle is labeled "Original Diameter" with a black arrow pointing from the label to its circumference. This dashed circle is slightly smaller than the "Rotor Disk."
3.  **Reduced 1/3 Blade Height Diameter:** Inside the "Original Diameter" dashed circle, another solid black circle is labeled "Reduced 1/3 Blade Height Diameter" with a black arrow pointing from the label to its circumference. This circle is smaller than the "Original Diameter" circle.
4.  **Locus of Centroid:** Inside the "Reduced 1/3 Blade Height Diameter" circle, a smaller dashed black circle is labeled "Locus of Centroid" with a black arrow pointing from the label to its circumference. This circle is centered on the same vertical axis as the other circles but is offset horizontally to the left from their common vertical center line.
5.  **Central Crosshairs:** At the geometric center of the "Rotor Disk," "Original Diameter," and "Reduced 1/3 Blade Height Diameter" circles, there is a small crosshair symbol, indicating the center point.
6.  **Shaded Sector:** A dark grey, solid-filled sector (pie slice) is depicted. Its apex is at the center of the "Rotor Disk" (where the crosshairs are). The sector extends downwards and to the left, covering approximately 90 degrees. Its outer arc aligns with the "Reduced 1/3 Blade Height Diameter" circle. This shaded sector is associated with the label "Sector Centroid," with a black arrow pointing from the label to the approximate center of the shaded area.
7.  **Trajectory Line:** A horizontal dashed black line extends from the left side of the diagram, passing through the center of the "Rotor Disk" and extending to the right. This line is labeled "Trajectory" with a black arrow pointing to the left, indicating direction.
8.  **Reference Angle for all Rotors:** Below the "Trajectory" line, a curved black arrow with a perpendicular line segment indicates an angle. This is labeled "Reference Angle for all Rotors." The curved arrow starts from the horizontal "Trajectory" line and sweeps upwards, suggesting an angular measurement relative to the trajectory.
9.  **Limit of swept Path:** Two horizontal solid black lines are present. One is above the "Trajectory" line and the other is below it. Both are labeled "Limit of swept Path." These lines are tangential to the "Rotor Disk" at its top and bottom points, respectively, defining the vertical extent of the rotor's swept area.
10. **Rotation Arrow:** At the bottom right of the diagram, a curved black arrow indicates clockwise rotation, labeled "Rotation."

Contextual Linkage:
The diagram visually defines the geometric parameters and spatial relationships relevant to analyzing a tri-sector rotor burst. The "Rotor Disk" represents the overall boundary. The "Original Diameter" and "Reduced 1/3 Blade Height Diameter" define specific radial extents within the rotor. The "Locus of Centroid" indicates the possible positions of the centroid of a fragment. The "Sector Centroid" highlights a specific fragment shape and its centroid. The "Trajectory" and "Reference Angle for all Rotors" establish the direction of fragment travel and a reference for angular measurements. The "Limit of swept Path" defines the vertical envelope of the rotor's operation. The "Rotation" arrow indicates the direction of the rotor's spin. This entire setup is crucial for understanding how fragments might be ejected and their potential paths.](file_wSyEACTCE2d/image052.png)

TRI-SECTOR
ROTOR BURST

FIGURE
3

![Aviation.Bot AI suggestion, not from EASA source: The image displays a cross-sectional diagram illustrating the typical layout and spatial distribution of various aircraft systems, including hydraulic, fuel, bleed air, and electrical components, within the rotor plane of an engine or APU.

Detailed Description: The image features a large, thick black circular outline representing an aircraft fuselage cross-section. A prominent thick black horizontal line divides the lower half of the circle, suggesting a structural deck or floor. A dashed horizontal line, labeled "WL73.5", is positioned slightly above this structural line on the right side, extending outwards from the fuselage outline.

Various aircraft systems and components are depicted within this cross-section, connected to their respective labels by thin black lines:

*   **Top Section:**
    *   A solid black circle in the upper-left quadrant is labeled "GEN 1".
    *   A solid black circle in the upper-right quadrant is labeled "GEN 2".
    *   Text "HYDRAULIC SYSTEM NO.1 [PRESSURE, RETURN]" is positioned in the upper-left, with a line pointing to a location within the upper-left quadrant.
    *   Text "HYDRAULIC SYSTEM NO.2 [PRESS., RETURN, BRAKE 2]" is positioned in the upper-right, with a line pointing to a location within the upper-right quadrant.

*   **Mid-Section (near the horizontal structural line):**
    *   On the left side, two small, empty rectangular boxes are positioned on the horizontal structural line. The left box is associated with "RUDDER LH 2X", and the right box with "ELEVATOR LH 2X".
    *   Below these boxes, two small, empty circles are present. The left circle is associated with "MOTIVE FLOW", and the right circle with "FUEL FEED".
    *   On the right side, two small, empty rectangular boxes are positioned on the horizontal structural line. The left box is associated with "RUDDER RH 2X", and the right box with "ELEVATOR RH 2X".
    *   Below these boxes, two small, empty circles are present. The left circle is associated with "MOTIVE FLOW", and the right circle with "FUEL FEED".
    *   Centrally, just below the horizontal structural line, two small, empty circles are associated with "APU FUEL PRESS+RETURN".

*   **Lower Section:**
    *   A larger, empty circle is centrally located, labeled "BLEED AIR 14TH".
    *   To the left of "BLEED AIR 14TH", a small, solid black circle is labeled "HYD PUMP 1B".
    *   To the right of "BLEED AIR 14TH", a small, solid black circle is labeled "HYD PUMP 2B".
    *   In the lower-left quadrant, a small, solid black circle is labeled "H-STAB TRIM".
    *   Adjacent to "H-STAB TRIM", another small, solid black circle is labeled "APU FUEL NEG-G".
    *   Further left and down, a small, solid black circle is labeled "APU GEN 3".
    *   A small, empty circle in the lower-left is associated with "HYDRAULIC SYSTEM NO.3 PRESSURE + RETURN".
    *   In the lower-right quadrant, a small, solid black circle is labeled "H-STAB TRIM CH1".
    *   Below "H-STAB TRIM CH1", two small, empty circles are associated with "TAIL TANK TRANSFER + REFUEL/DEFUEL".
    *   Numerous other small, unlabeled empty and solid black circles are distributed throughout the lower half of the fuselage cross-section.

Contextual Linkage: This diagram visually represents the physical arrangement of critical aircraft systems within a specific cross-section, identified as the "TYPICAL LAYOUT OF SYSTEMS IN ROTOR PLANE" by the surrounding text. The depiction of components like hydraulic systems (No.1, No.2, No.3), fuel lines, flight control elements (Rudder, Elevator, H-Stab Trim), bleed air systems, and generators (GEN 1, GEN 2, APU GEN 3) illustrates their spatial relationships and potential vulnerability to events such as uncontained engine or APU failure. The "WL73.5" indicates a specific vertical reference point within the aircraft structure, crucial for precise component placement and damage assessment.](file_wSyEACTCE2d/image053.png)

TYPICAL
LAYOUT OF SYSTEMS IN ROTOR PLANE

FIGURE
4

![Aviation.Bot AI suggestion, not from EASA source: This diagram illustrates the concept of trajectory range plotting for uncontained engine/APU failure, specifically showing how a fragment from a right engine can impact and sever aircraft control cables.

Detailed Description:
The image displays a two-dimensional engineering drawing, viewed looking forward, depicting the cross-section of an aircraft fuselage and an engine, along with associated control cables and fragment trajectories.

At the top left, a large circle with intersecting horizontal and vertical dashed centerlines represents a cross-section of an aircraft component, likely the fuselage. Above this circle, the text "VIEW LOOKING FORWARD" is centrally placed, aligned with the vertical dashed centerline.

To the right of the fuselage cross-section, a second large circle with intersecting horizontal and vertical dashed centerlines represents a cross-section of an engine. An arrow labeled "Rotation" is positioned above and to the right of this engine cross-section, indicating a clockwise rotational direction.

Below the fuselage cross-section, a horizontal dashed line extends across the lower portion of the diagram, representing a structural plane or component. Along this dashed line, four small, solid black circles are depicted, representing control cables.
* On the left side, two cables are shown. The upper left cable is connected by a solid line to the label "LEFT ELEVATOR CABLES". The lower left cable is connected by a solid line to the label "LEFT RUDDER CABLES".
* On the right side, two cables are shown. The upper right cable is connected by a solid line to the label "RIGHT RUDDER CABLES". The lower right cable is connected by a solid line to the label "RIGHT ELEVATOR CABLES".

Two irregular, shaded, dark grey shapes are positioned below the horizontal dashed line, between the left and right cable groups. The shape on the right is labeled "A", and the shape on the left is labeled "B". These shapes appear to represent areas affected by fragment impact.

Originating from the center of the right engine cross-section, two solid lines extend downwards and to the left, representing fragment trajectories.
* An arc with an arrow indicates an angle of "240°" measured clockwise from the vertical dashed centerline of the engine to the left trajectory line.
* Another arc with an arrow indicates an angle of "221°" measured clockwise from the vertical dashed centerline of the engine to the right trajectory line.
These trajectory lines pass through the locations of the right rudder cables and the shaded areas 'A' and 'B'.

At the bottom of the diagram, an "EXAMPLE:" text block provides a specific scenario: "The right rudder cables are cut by a 1/3 fan fragment from the right engine at all trajectory angles between 221° and 240°. Trajectory range A - B is therefore 19°".

Contextual Linkage:
The diagram visually represents the trajectory of a fragment originating from the right engine. The two solid lines extending from the engine's center define an angular range (221° to 240°) within which the fragment travels. This angular range is shown to encompass the "RIGHT RUDDER CABLES" and the shaded areas 'A' and 'B'. The example text explicitly links this visual representation to a scenario where a 1/3 fan fragment from the right engine cuts the right rudder cables within this specified angular trajectory, resulting in a trajectory range of 19° (240° - 221°). The shaded areas 'A' and 'B' visually delineate the extent of this 19° trajectory range at the level of the control cables.](file_wSyEACTCE2d/image054.png)

TRAJECTORY
RANGE PLOTTING

FIGURE
5

![Aviation.Bot AI suggestion, not from EASA source: The image depicts a geometric diagram illustrating typical trajectory plotting, showing the relationship between a "TARGET" and two origin points ("N1" and "N2") with associated trajectories, and the derivation of a "Locus of Centroid" and "Swept Path" at their convergence.

Detailed Description: The diagram is presented against a plain white background. At the approximate center of the lower half of the image, there is a horizontally oriented black rectangular box with a thick black outline, labeled "TARGET" in capital, sans-serif font.

To the lower right of the "TARGET" box, there is a black-outlined circle labeled "N1" in its center. A solid black line segment extends from the center of the "N1" circle to its circumference, labeled "1R". A small right-angle symbol indicates that this "1R" line segment is perpendicular to a solid black line labeled "T 1" that passes tangentially to the "N1" circle. Another solid black line, labeled "T 2", also passes through the "N1" circle, originating from the bottom-left of the image and extending towards the "TARGET" and beyond. A dashed grey line extends from the center of the "N1" circle towards the "TARGET".

To the upper left of the "TARGET" box, there is another black-outlined circle labeled "N2" in its center. Similar to "N1", a solid black line segment extends from the center of the "N2" circle to its circumference, labeled "1R". A small right-angle symbol indicates that this "1R" line segment is perpendicular to a solid black line labeled "T 1" that passes tangentially to the "N2" circle. Another solid black line, labeled "T 2", also passes through the "N2" circle, originating from the top-left of the image and extending towards the "TARGET" and beyond. A dashed grey line extends from the center of the "N2" circle towards the "TARGET".

Four solid black lines converge towards a point in the upper right quadrant of the image. Two of these lines originate from the "TARGET" box, extending upwards and to the right. The other two lines originate from the vicinity of the "N1" and "N2" circles, specifically from the points where the "T 2" lines intersect the "TARGET" box's corners, and extend towards the upper right convergence point.

At this convergence point in the upper right, there is a complex geometric construction:
1.  A small solid black circle is present.
2.  Concentric with this small solid circle, there is a slightly larger dashed black circle.
3.  Above these circles, a solid black "V"-shaped polygon is depicted, with its apex pointing downwards, positioned within the dashed circle. The "V" shape's two upper vertices are on the circumference of the dashed circle.
4.  An arrow points from the text "LOCUS OF CENTROID" (positioned above and to the left of the "V" shape) to the common center of the small solid circle and the dashed circle.
5.  Above the "V" shape, two vertical dashed lines indicate a horizontal dimension. The text "SWEPT PATH 2R" is centered horizontally between these two dashed lines. The left dashed line aligns with the leftmost point of the dashed circle, and the right dashed line aligns with the rightmost point of the dashed circle, indicating that "SWEPT PATH 2R" represents the diameter of the dashed circle.
6.  Two curved arrows are drawn, one on each side of the converging lines, indicating an angle or sweep. The lower curved arrow is between the lower two converging lines, and the upper curved arrow is between the upper two converging lines.

Contextual Linkage: This diagram visually represents the concept of trajectory plotting, likely for uncontained engine failure debris. The "TARGET" represents a critical area or component on the aircraft. "N1" and "N2" likely represent different origins or conditions for fragment trajectories. The "1R" indicates a radius associated with these origins. The "T 1" and "T 2" lines represent different trajectory paths. The convergence of these trajectories leads to the definition of a "LOCUS OF CENTROID" and a "SWEPT PATH 2R", which are crucial for determining the potential impact area or risk zone of fragments. The "SWEPT PATH 2R" explicitly indicates a diameter, suggesting a circular area of potential impact or a range of possible fragment locations.](file_wSyEACTCE2d/image055.png)

TYPICAL
TRAJECTORY PLOTTING

FIGURE
6

![Aviation.Bot AI suggestion, not from EASA source: The image provides two three-dimensional diagrams illustrating the angular definitions of a "Threat Window" for uncontained engine/APU failure, specifically detailing translational and spread angles relative to a plane of rotation and a target.

Detailed Description:
The image consists of two distinct three-dimensional perspective diagrams, arranged vertically. Both diagrams depict a "TARGET" object and a reference plane, along with various angular measurements and a fragment path.

**Upper Diagram:**
This diagram illustrates translational aspects.
*   A large, horizontally elongated ellipse, labeled "PLANE OF ROTATION," is depicted in perspective, appearing to recede into the background.
*   At the center of the "PLANE OF ROTATION" is a small circle with a cross, indicating a central point or axis of rotation. Dotted lines extend radially from this center, forming a coordinate system within the plane.
*   Above and to the left of the "PLANE OF ROTATION" is a rectangular, block-like object labeled "TARGET." The front face of the "TARGET" shows two circular openings.
*   A shaded, wedge-shaped volume, labeled "FRAGMENT SWEPT PATH," originates from the center of the "PLANE OF ROTATION" and extends towards the "TARGET." The area of this wedge is filled with a dot pattern.
*   An arrow points from the "FRAGMENT SWEPT PATH" to a text box containing "SEE FIGURE 6 FOR DETAILS," indicating a cross-reference.
*   Within the "PLANE OF ROTATION," an arc labeled "φ2 - φ1" is shown between two radial lines originating from the center, defining an angle. This arc is associated with the "FRAGMENT SWEPT PATH."
*   Two curved arrows extend from the "PLANE OF ROTATION" outwards, indicating larger angular extents:
    *   The upper curved arrow is labeled "TRANSLATIONAL RELEASE ANGLE."
    *   The lower curved arrow is labeled "TRANSLATIONAL RISK ANGLE." These angles appear to encompass the "FRAGMENT SWEPT PATH" within the "PLANE OF ROTATION."

**Lower Diagram:**
This diagram illustrates spread aspects, perpendicular to the plane of rotation.
*   A rectangular, block-like object, identical to the "TARGET" in the upper diagram, is labeled "TARGET." It also features two circular openings on its front face.
*   Below and to the right of the "TARGET" is a flat, rectangular plane, labeled "PLANE NORMAL TO PLANE OF ROTATION." This plane is oriented horizontally, perpendicular to the implied axis of rotation from the upper diagram.
*   At the center of this "PLANE NORMAL TO PLANE OF ROTATION" is a small circle with a cross, indicating a central point. Dotted lines extend from this center, forming a coordinate system within the plane.
*   A shaded, wedge-shaped volume originates from the center of the "PLANE NORMAL TO PLANE OF ROTATION" and extends towards the "TARGET." This volume is similar in appearance to the "FRAGMENT SWEPT PATH" in the upper diagram and is filled with a dot pattern.
*   An arrow points from the shaded volume towards a label "SPREAD ANGLE," positioned to the left of the volume.
*   Within the "PLANE NORMAL TO PLANE OF ROTATION," an arc labeled "ψ2 - ψ1" is shown between two lines originating from the center and extending towards the "TARGET." An arrow points from this arc to a label "SPREAD RISK ANGLE," positioned to the right of the arc.

Contextual Linkage:
The image defines the geometric parameters for assessing the "Threat Window" of uncontained engine/APU failure. The upper diagram illustrates the angular extent of fragment trajectories within the plane of rotation, defining "Translational Release Angle" and "Translational Risk Angle" using the "φ2 - φ1" notation. The lower diagram illustrates the angular extent perpendicular to the plane of rotation, defining "Spread Angle" and "Spread Risk Angle" using the "ψ2 - ψ1" notation. Both diagrams show a "FRAGMENT SWEPT PATH" directed towards a "TARGET," which represents the component or area susceptible to damage. The reference to "SEE FIGURE 6 FOR DETAILS" indicates that the "FRAGMENT SWEPT PATH" is further elaborated in another figure.](file_wSyEACTCE2d/image056.png)

DEFINITION
- THREAT WINDOW

FIGURE
7

![Aviation.Bot AI suggestion, not from EASA source: **Overall Summary:** This chart, titled "ENGINE ROTOR FAILURE - SYSTEM EFFECTS," illustrates the vulnerability of various aircraft systems and components to damage from an uncontained engine rotor failure, mapping specific impact types across a range of trajectory angles for a High-Pressure (H.P.) Turbine 1 on the right engine.

**Detailed Description:** The image displays a grid-based chart with the main title "ENGINE ROTOR FAILURE - SYSTEM EFFECTS" centered at the top. Below this, to the left, are labels indicating the subject of the analysis: "ENGINE: RIGHT" and "COMPONENT: H.P. TURBINE 1", with "SIZE: In." next to "COMPONENT:".

The chart is organized into several columns and rows:

1.  **System Categories (Leftmost Column):** This column lists major aircraft system groups in bold text: "FLIGHT CONTROLS", "HYDRAULIC POWER", "FIRE PROTECTION", "FUEL", "ELECTRICAL POWER", "ENVIRONMENTAL", "POWER PLANT", and "APU".
2.  **Components/Subsystems (Second Column):** This column details specific components or subsystems within each category. Examples include "RUDDER", "ELEVATOR", "H-STAB", "TRIM" (under FLIGHT CONTROLS); "POWER #1", "PLUMBING #1", "POWER #2", "PLUMBING #2", "PLUMBING #3" (under HYDRAULIC POWER); "ENGINE FIREX#1", "ENGINE FIREX#2", "APU FIREX" (under FIRE PROTECTION); "ENGINE FEED MOTIVE", "ENGINE FEED FLOW", "APU FEED", "TAIL TANK LINES" (under FUEL); "GENERATOR #1", "GENERATOR #2", "GENERATOR #3", "BATTERY MAIN", "BATTERY AUX" (under ELECTRICAL POWER); "CABIN PRES URE", "PNEUMATIC 10TH STAGE", "SUPPLY", "ACU", "OUTPUT", "ENGINE CON ROL" (under ENVIRONMENTAL); "OPPOSITE N CELLE" (under POWER PLANT); and "APU ENCLO URE" (under APU).
3.  **Specific Elements/Channels (Third Column):** This column provides further detail for some components, such as "CABLES" for Rudder and Elevator, "CHANNEL# 2" for H-Stab, "CHANNEL# 1" for Trim, "A" or "B" for Hydraulic Power components, "L" or "R" for Engine Feed and Environmental components, and "REFUEL" or "TRANSFER" for Tail Tank Lines.
4.  **IN/OUT Values (Fourth Column):** This column contains two sub-columns, "IN" and "OUT", listing three-digit numerical values (e.g., "244" IN, "252" OUT for Rudder Cables L). These values are associated with each specific component or element row.
5.  **Trajectory Angles in Degrees (Main Grid):** The top row of the main grid is labeled "TRAJECTORY ANGLES IN DEGREES" and spans horizontally across the chart. It is subdivided into columns representing 5-degree or 10-degree increments, starting from "210" and extending to "315". The specific column headers are: "210", "215", "220", "225", "230", "235", "240", "245", "250", "255", "260", "265", "270", "275", "280", "285", "290", "295", "300", "305", "310", "315".

The cells within the main grid are filled with distinct patterns to indicate the type of impact:
*   **Solid Black Rectangles:** Represent a "DIRECT HIT".
*   **"OOOOOO" pattern:** Represents an impact from the "OPPOSITE ENGINE FUEL LINE".
*   **"XXXXXX" pattern:** Represents an impact from the "OPPOSITE GENERATOR".
*   **"FFFFFF" pattern:** Represents an impact from the "APU FUEL LINE" (though no cells in the visible chart contain this pattern).

**Legend:** A legend is provided at the bottom of the chart, explicitly defining the patterns: "LEGEND: [Solid Black Rectangle] = DIRECT HIT OOOOOO = OPPOSITE ENGINE FUEL LINE XXXXXX = OPPOSITE GENERATOR FFFFFF = APU FUEL LINE".

**Figure Title:** The chart is identified as "FIGURE 8 - SAMPLE ROTOR STAGE PLOTTING CHART" below the legend.

**Contextual Linkage:**
This chart serves as a visual representation of "threat windows" for uncontained engine rotor failure, as referenced in the surrounding text (e.g., "Establish from the table in Figure 8 the threat windows where, due to combination of individual damages, a catastrophic risk exists."). It maps the angular vulnerability (trajectory angles) of specific aircraft systems and components to debris from an H.P. Turbine 1 failure on the right engine. The "IN" and "OUT" values likely define the angular extent or critical range of the component itself, while the patterns in the trajectory angle grid indicate the type of impact (direct or from specific opposite-side components) within those angular sectors.](file_wSyEACTCE2d/image057.png)

Compare / EASA/ Incorporated Amendments/ Compare & Highlight Differences

Appendix 1 to AMC 20-128A User's Manual

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