AMC E 130 Fire Protection

• ED Decision 2018/014/R found in: CS-E Amdt 5 - Engines (Dec 2018)

AMC E 130 Fire Protection ED Decision 2018/014/R (1) Definitions (a) Drain and Vent Systems: Components which are used to convey unused or unwanted quantities of flammable fluid or vapour away from the Engine. (b) External Lines, Fittings and Other Components: Engine parts conveying flammable fluids and which are external to the main Engine casings, frames and other major structure. These parts include, but are not limited to, fuel or oil tubes, accessory gearbox, pumps, heat exchangers, valves and Engine fuel control units. (c) Fire Hazard: (1) The unintentional release or collection of a hazardous quantity of flammable fluid, vapour or other materials; or (2) a Failure or malfunction which results in an unintentional ignition source within a fire zone; or (3) the potential for a Hazardous Engine Effect as the result of exposure to a fire. (d) Fire-resistant, Fireproof: the definitions of "Fire-resistant" and "Fireproof" are given in CS-Definitions; they imply that the functioning of the part under fire condition should not hazard the aircraft. (e) Hazardous quantity: An amount of fluid, vapour or other material which could sustain a fire of sufficient time and severity to create damage potentially leading to a Hazardous Engine Effect. In the absence of a more suitable determination of a hazardous quantity of flammable fluid, this can be assumed to be 0.25 litre or more of fuel (or a quantity of flammable material of equivalent heat content). (2) General (a) Intent The intent of [CS-E 130](#_DxCrossRefBm1371447656) is to give assurance that the design, materials and construction techniques utilised will minimise the probability of the occurrence, the consequences and the spread of fire. (b) Objectives With respect to the above intent, the primary objectives are to (1) contain, isolate and withstand a fire or prevent any sources of flammable material or air from feeding an existing fire and (2) increase the probability that the Engine Control System and accessories will permit a safe shutdown of the Engine or feathering of the Propeller (if the Propeller control system is part of the Engine design) and subsequently maintain that condition. (c) Determination of level of fire protection [CS-E 130(b)](#_DxCrossRefBm1371447656) requires that all flammable fluid conveying parts or components be at least Fire-Resistant, whereas [CS-E 130(c)](#_DxCrossRefBm1371447656) requires flammable fluid tanks and associated shutoff means to be Fireproof. It should then be determined which level of fire protection should be shown for each component requiring a fire protection evaluation. The 5-minute exposure which is associated with a “Fire-Resistant” status provides a reasonable time period for the flight crew to recognise a fire condition, shut down the appropriate Engine and close the appropriate fuel shutoff valve(s). This cuts off the source of fuel. Oil system components of turbine Engines, however, may continue to flow oil after the Engine has been shut down because of continued rotation. The supply of oil to the fire might exist for as long as the continued rotation effects are present or until the oil supply is depleted. According to these assumptions, in general, components which convey flammable fluids can be evaluated to a Fire resistant standard provided the normal supply of flammable fluid is stopped by a shutoff feature (also see [CS-E 570(e)(1)](#_DxCrossRefBm1371447607)). Oil system components may need to be evaluated from the standpoint of fire hazard (quantity, pressure, flow rate, etc.) to determine whether Fire-resistant or Fireproof standards should apply. It should be noted that, historically, most oil system components have been evaluated to a Fireproof standard. Other flammable fluid conveying components (except flammable fluid tanks), such as hydraulic and thrust augmentation systems, should be evaluated in a similar manner. Flammable fluid tanks should be Fireproof as required by [CS-E 130(c)](#_DxCrossRefBm1371447656). (d) Pass / fail criteria When a fire test is performed, the following acceptance criteria should be considered: — To maintain the ability to perform those functions intended to be provided in case of fire, — No leakage of hazardous quantities of flammable fluids, vapours or other materials, — No support of combustion by the constituent material of the article being tested, — No burn through of firewalls, — No other conditions which could produce Hazardous Engine Effects. (i) Functions The functions intended to be provided in case of fire will be determined on a case by case basis. For example, Engine Control Systems should not cause a Hazardous Engine Effect while continuing to operate but should allow or may cause a safe shutdown of the Engine at any time within the required exposure time period. A safe Engine shutdown at any time during the fire resistance test is an acceptable outcome for this type of component, provided the safe shutdown is maintained until the end of the 5 minutes test period. For a flammable fluid tank shutoff valve, the valve should be operable (to close) or should default closed, and be capable of maintaining this position without leakage of a hazardous quantity of flammable fluid until the end of the 15 minute test period. The above examples are included to illustrate the case by case nature of making this determination. (ii) Leakage of flammable fluid At no time during or at the end of the test should the test article leak a hazardous quantity of flammable fluid. (iii) Support of combustion Consideration should be given to non-self-extinguishing fire test events. This type of event could be either combustion of the constituent material of the test article or combustion of flammable fluid leaking from the component. In general, these events should continue to be cause for Failure of the test, unless it can be shown that the constituent material supporting combustion is not a hazardous quantity of flammable fluid, vapour, or material as defined in this AMC. This has been the case for certain electronic components. Current technology electronic components often use circuit board potting compounds internal to the casings of the Engine Control System that may support combustion when heated sufficiently or when exposed to fire. These compounds can also flow under high heat and may leak through the casings. Therefore, such materials may support a small intensity fire internal and / or external to the casing for a limited period of time after the test flame is removed. (iv) Firewall At no time during or at the end of the test should a firewall component fail to contain the fire within the intended zone or area. Implied with this outcome is the expectation that the firewall component will not develop a burn through hole and will not fail in any manner at its attachment or fire seal points around the periphery of the component and will not continue to burn after the test flame is removed. There should not be backside ignition. (v) Other conditions At no time during or at the end of the test should a Hazardous Engine Effect result. (3) Materials (a) Experience has shown that when using materials such as magnesium and titanium alloys, appropriate design precautions may be required to prevent an unacceptable fire hazard. Consideration should be given to the possibility of fire as a result of rubbing or contact with hot gases. Any material used for abradable linings needs to be assessed to ensure that fire or explosion hazards are avoided. Consideration should also be given to the effects of mechanical Failure of any Engine component and to the effects of dimensional changes resulting from thermal effects within the Engine. (b) Use of Titanium Many titanium alloys used for manufacturing Engine rotor and stator blades will ignite and may sustain combustion, if the conditions are appropriate. In general, titanium fires burn very fast and are extremely intense. The molten particles in titanium fires generate highly erosive hot sprays which have burned through compressor casings with resulting radial expulsion of molten or incandescent metal. In such cases, depending on the installation, the aircraft could be hazarded. In showing compliance with [CS-E 130(a)](#_DxCrossRefBm1371447656) the applicant should assess the overall design for vulnerability to titanium fires. If this assessment cannot rule out the possibility of a sustained fire, then it should be shown that a titanium fire does not result in a Hazardous Engine Effect. Based on experience, the following precautions can reduce the susceptibility of Engines to titanium fires: — The type of alloy i.e. its constituents other than titanium; — Blade / casing coatings or mechanical linings which inhibit ignition or subsequent combustion; — The way in which the design minimises potentially dangerous rubs by such methods as: — Large inter blade row clearances; — The use of appropriate abradable materials in areas of potential rub of sufficient depth to accommodate predicted rotor or stator deflections including those likely to occur in Fault conditions; — Not using titanium for adjacent rotating and static parts; — Taking full account of rotor movements under transient and bearing Failure conditions; — Ensuring that thin, easily ignited titanium sections are unlikely to be shed at the front of the Engine. (c) Use of Magnesium Many magnesium alloys used in the manufacture of Engine components are highly combustible when in finely divided form, such as chips or powder. Therefore the use of magnesium alloys in thin sections or where they are exposed to corrosion, rubbing or high scrubbing speeds should be carefully evaluated. In showing compliance with [CS-E 130](#_DxCrossRefBm1371447656), the applicant should assess the overall design for vulnerability to magnesium fires. If this assessment cannot rule out the possibility of a sustained fire, then it should be shown that a magnesium fire would be confined to areas within the Engine such that it does not result in a Hazardous Engine Effect. (d) Abradable Linings Many fan, compressor and turbine modules have abradable linings between rotating blade tips and stator casings. Depending upon the material used in the abradable lining, experience has shown that fire or explosion can occur in the presence of an ignition source if a significant amount of lining is removed during rubs between rotor and stator. Under certain conditions, auto-ignition can occur in the mixture of small particles extracted from the abradable linings and hot flow path gases. These situations should be evaluated for each fan, compressor and turbine stage which has an abradable lining. (e) Absorbent Materials Absorbent materials should not be used in close proximity to flammable fluid system components unless they are treated or covered to prevent the absorption of a hazardous quantity of such fluid. (4) Specific interpretations (a) Test equipment and calibration Acceptable procedures for calibration of the relevant burners for the tests, and the standard flame, are defined in the ISO 2685 standard. A pre test calibration to verify that the standard flame temperature and heat flux is achieved is necessary for each test. To ensure that flame conditions are constant throughout the test either the flow parameters should be shown to be constant throughout the test or a post-test calibration should be performed to show equivalency with pre-test values. (b) Flame impingement location The test flame generally should be applied to the test article feature(s) that is determined by analysis or test to be the most critical with respect to surviving the effects of the fire. For this approach, determination of the flame impingement location(s) should consider, as a minimum, the following potential factors: materials; geometry; part features; local torching effects; vibration; internal fluid level, pressure and flow rate; surface coatings; fire protection features; etc. Alternatively, the applicant may consider all potential sources of fire in the intended installation when determining test flame impingement location specifications. The intent is to identify locations or features which cannot be directly impinged by fire, and evaluating critical features which can be directly impinged. If the applicant chooses this installation analysis approach, it should be based on the actual intended installation, and should consider, as a minimum, the factors noted above, plus the following potential installation specific factors: cowling and nacelle structure; under cowl airflow; aircraft Engine build up hardware; etc. Such installation analyses should avoid simple generalities, such as “the most likely flame direction is vertical assuming fuel collects at the bottom of the cowl,” and should be co-ordinated with the installer. If this approach is utilised, each new installation will need to be re-evaluated against the original fire protection substantiation to confirm its applicability to the new installation. Lastly, due consideration should be given to fire protection features such as fire shields, fire protective coatings or other methods so as not to discourage or invalidate their use with respect to compliance with [CS-E 130](#_DxCrossRefBm1371447656). (c) Operating parameters for test articles The operating characteristics and parameters of the test article should be consistent, but conservative, with respect to the conditions which might occur during an actual fire situation. For example, where a high internal fluid flow increases the heat sink effect, and is less conservative with respect to fire susceptibility, a minimum flow condition should be specified for the test. The same is true for examples relating to internal fluid temperatures or quantity or other parameters. (d) Electrical Systems components For compliance with [CS-E 130(c)](#_DxCrossRefBm1371447656), the effects of fire on components of the electrical system should be evaluated. Electrical cables, connectors, terminals and equipment, installed in or on the Engine, in designated fire zones should be at least fire resistant. (5) Flammable fluid tank fire test In the absence of an acceptable installation assessment, the fire test flame should be applied to the tank location(s) or feature(s) that has been determined by analysis or test to be the most critical with respect to fire susceptibility (i.e. the location or feature least likely to survive the test conditions or meet the test pass / fail criteria). In selecting the flame application location, the tank installation and all features of the tank assembly should be considered. Typical tank features include, but are not limited to tank body, inlet and outlet assemblies, sight glass, drain plug, magnetic chip detector, quantity sender assembly, vent line assembly, filler cap and scupper, mounts, shutoff valve, temperature sensor, and air/fluid separator assembly. Tanks can be designed and manufactured with any combination of the above features, or other features not listed, and of varying materials. Therefore, in some instances, compliance with [CS-E 130](#_DxCrossRefBm1371447656) may need to be supported by data from other fire tests, multiple location testing, sub component level tests, or service experience, to cover all tank assembly features. Also, other aspects of determining impingement location should be considered, such as vent system performance (experience has shown that oil tank fire tests have failed due to high internal pressure and inadequate venting), the lack of heat sink effect for tank features at or above the operating level of the tanks fluid contents and the effect of any special protective features (shields, coatings, feature placement, etc.) incorporated into the design. With respect to fluid quantity, the tank quantity at the start of the test should be no greater than the minimum dispatchable quantity, unless a greater quantity is more severe. Relative to flow rate, the first 5 minutes of the test should be conducted at the most critical operating condition (typically a minimum flight idle flow rate) and the subsequent 10 minutes should be conducted at an Engine shutdown flow rate with consideration of the effect of any continued rotation. The test may be run, at the applicant’s option, for 15 minutes at the most critical condition (worst case of Engine operating or in flight shutdown conditions). With respect to fluid temperature, this should be at its maximum value (the greatest of steady state or transient limit) at the start of the test, unless a lower temperature is more severe. The tank internal pressure should be the normal working pressure for the operating conditions at the start of the test. It is understood that these values may change due to the test conditions. The tank design and its intended application should be reviewed to provide reasonable assurance that the test set-up reflects the most critical flame impingement orientation and operating conditions for the intended application. (6) Drain and Vent Systems [CS-E 130(b)](#_DxCrossRefBm1371447656) allows certain parts to be exempt from the specifications because they do not typically contain or convey flammable fluids during normal Engine operation. This refers to normal operation in a typical flight mission. It is not intended to impose a fire resistance demonstration for all parts of the Engine which might contain, convey or be wetted by flammable fluids in all possible Failure scenarios. An example of parts which might be exempted is a combustor drain system which typically drains off residual fuel after an aborted Engine start. This might also be the case of the majority of individual drains and vents. However, a shrouded fuel line is considered as being a single assembly which cannot be dissociated into the main fuel line and its envelop (acting as a drain in case of a Failure in the main fuel line) and should comply with [CS-E 130](#_DxCrossRefBm1371447656) as a component carrying flammable fluid. In this particular case, after the exposure to the flame, the external envelope may be destroyed provided the general pass / fail criteria described in paragraph (2)(d) of this AMC are complied with. In the case of a drain and vent system which would flow a hazardous quantity of flammable fluid during continued rotation after shut down of the Engine, then a fireproof standard may be appropriate. The function of each drain or vent should be carefully reviewed in making these determinations (7) Air Sources In accordance with [CS-E 130(a)](#_DxCrossRefBm1371447656), the applicant should evaluate the effect of fire on components conveying bleed air and evaluate whether Failure of such components could further increase the severity or duration of a fire within a fire zone. (8) Firewall The overall intent of [CS-E 130(d)(2)](#_DxCrossRefBm1371447656) is to provide specifications for the proper functioning of a firewall which are consistent with the aircraft specifications on firewalls. In no case should a hazardous quantity of flammable fluid or vapour pass around the firewall. Also, the firewall should contain the fire without resulting in a Hazardous Engine Effect. (9) Shielding The overall intent of [CS-E 130(b)](#_DxCrossRefBm1371447656) specification concerning the shielding and location of components is to minimise the possibility of liquid flammable fluids contacting ignition sources and igniting. Ignition sources include hot surfaces with temperatures at or above typical flash points for aviation fuels, oils, and hydraulic fluids, or any component that produces an electrical discharge. Compliance with this specification may be shown by installation of drainage shrouds around flammable fluid lines or fittings; installation of spray shields to deflect leaking fuel away from ignition sources, and general component location on the Engine which minimises the possibility of starting and supporting a fire. Therefore, the overall substantiation should show that leaked flammable fluid would be unlikely to impinge on an ignition source to the extent of starting and supporting a fire. [Amdt. No.: E/1] [Amdt No: E/5]