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Appendix 1 to AMC 20-158 Generic transfer functions and attenuation

Available versions for ERULES-1963177438-9014

ED Decision 2015/017/R found in: AMC-20 Amdt 21 - Airworthiness of Products, Parts and Appliances (Apr 2021)

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Appendix 1 to AMC 20-158 Generic transfer
functions and attenuation

ED Decision 2015/017/R

1.         Generic transfer functions

a.         Suitable
transfer functions for calculating the bulk current injection test levels for
Level A display systems (see paragraph 9.k.) are given in Figures A1-1 through
A1-5. These are derived generic transfer functions acquired from test results
obtained from a significant number of aircraft. The test results were then
processed to establish a 95 per cent population probability.

b.         The
transfer functions are normalised to a 1 V/m HIRF environment and may be
multiplied linearly by the external HIRF environment to establish the bulk
current injection test level requirements in the frequency range from 10 kHz
up to 400 MHz. For example, if the HIRF environment is 100 V/m at 3 MHz, then
using Figure A1-1, multiply 0.7 mA/V/m by 100 V/m to establish a test level of
70 milliamperes (mA).

c.         Consult
the User’s Guide (SAE ARP 5583A/EUROCAE ED-107A) for details on the use of
generic transfer functions.

2.         Generic attenuation

a.         Figure
A1-6 shows the generic attenuation for frequencies from 100 MHz to 18 GHz that
can be used for determining the internal HIRF environment where equipment and
associated wiring for Level A display systems (see paragraph 9.k.) are
installed. This internal HIRF environment provides the test level for the
integrated system radiated susceptibility laboratory test. The external HIRF
environment should be divided by the appropriate attenuation, in linear units,
to determine the internal HIRF environment. For example, 12 dB or a 4:1
attenuation means the test level is the applicable external HIRF environment
electric field strength reduced by a factor of 4.

b.         Guidance
on the use of the generic attenuation is given below.

1.         No
attenuation. No attenuation credit can be used when the Level A display
equipment and associated wiring are located in aircraft areas with no HIRF
shielding, such as areas with unprotected non-conductive composite structures,
areas where there is no guarantee of structural bonding, or other open areas
where no shielding is provided. The applicant may choose to use no attenuation
for equipment that may be installed in a broad range of aircraft areas.

2.         6
dB attenuation. This attenuation is appropriate when the Level A display
equipment and associated wiring are located in aircraft areas with minimal
HIRF shielding, such as a cockpit in a non-conductive composite fuselage with
minimal additional shielding, or areas on the wing leading or trailing edges,
or in wheel wells.

3.         12
dB attenuation. This attenuation is appropriate when the Level A display
equipment and associated wiring are located entirely within aircraft areas
with some HIRF shielding, in aircraft with a metal fuselage or a composite
fuselage with shielding effectiveness equivalent to metal. Examples of such
areas are avionics bays not enclosed by bulkheads, cockpits, and areas near
windows, access panels, and doors without EMI gaskets. Current-carrying
conductors in this area, such as hydraulictubing, control cables, wire
bundles, and metal wire trays, are not all electrically bonded to bulkheads
they pass through.

4.         20
dB attenuation. This attenuation is appropriate when the Level A display
equipment and associated wiring are located entirely within the aircraft areas
with moderate HIRF shielding, in aircraft with a metal fuselage or a composite
fuselage with shielding effectiveness equivalent to metal. In addition, wire
bundles passing through bulkheads in these areas have shields electrically
bonded to the bulkheads. Wire bundles are installed close to metal structure
and take advantage of other inherent shielding characteristics provided by
metal structure. Current-carrying conductors such as hydraulic tubing, cables,
and metal wire trays are electrically bonded to all bulkheads they pass
through.

5.         32
dB attenuation. This attenuation is appropriate when the Level A display
equipment and all associated wiring to and from equipment are located entirely
within areas with very effective HIRF shielding to form an electromagnetic
enclosure.

c.         Different
attenuation values may be appropriate for different frequency ranges. For
example, 0 dB attenuation may be used for the frequency range of 100 MHz to
400 MHz, 6 dB attenuation for the frequency range of 400 MHz to 1 GHz, and 12
dB attenuation for the frequency range of 1 GHz to 18 GHz. If the applicant
intends to use different attenuation values for various frequency ranges, then
the supporting rationale should also be provided.

d.         Consult
the User’s Guide for details on the use of generic attenuation.

3.         Measured transfer functions or
attenuation. The applicant can produce their
own generic transfer functions and attenuation for their Level A display
systems (see paragraph 9.k.) based on actual measurements on their aircraft
models. These transfer functions and attenuation can then be used in their
HIRF compliance submission in place of the generic transfer functions and
attenuation specified in this appendix. The Agency encourages this approach
because it provides a more accurate reflection of the true internal HIRF
environment of the aircraft models. However, if the applicant intends to
produce their own generic transfer functions and attenuation, then this
approach should also be addressed in the HIRF compliance plan (see paragraph
8.a.) that is submitted to the Agency for approval.

Figure A1-1 — Generic transfer function — Aeroplane

![Aviation.Bot AI suggestion, not from EASA source: **Overall Summary:** The image displays a logarithmic plot illustrating a generic transfer function for calculating bulk current injection test levels for aeroplanes with a fuselage length of 25 meters or less, normalized to a 1 V/m High-Intensity Radiated Field (HIRF) environment.

**Detailed Description:** The image presents a two-dimensional line graph on a white background framed by a black border. The graph features a logarithmic scale on both its horizontal (X) and vertical (Y) axes, overlaid with a grid composed of dotted black lines.

The X-axis, positioned horizontally at the bottom of the graph, is labeled "Frequency - MHz" and ranges logarithmically from 0.01 MHz to 1000 MHz. Major tick marks are present at 0.01, 0.1, 1, 10, 100, and 1000. The Y-axis, positioned vertically along the left side of the graph, is labeled "mA/V/m" and ranges logarithmically from 0.001 mA/V/m to 1 mA/V/m. Major tick marks are present at 0.001, 0.01, 0.1, and 1.

A solid blue line represents the generic transfer function, connecting three distinct circular blue data points. The first visible segment of the blue line originates from the lower-left area of the graph, rising diagonally towards the upper-right. 1.  The first explicitly labeled data point is located at the coordinates (3, 0.7) on the graph, with the text "3, 0.7" positioned directly above it. 2.  From this point, the blue line extends horizontally to the right, indicating a constant value. 3.  The second labeled data point is at (15, 0.7), with the text "15, 0.7" positioned directly above it. 4.  From this second point, the blue line descends diagonally towards the lower-right. 5.  The third and final labeled data point is at (400, 0.3), with the text "400, 0.3" positioned to its right.

**Contextual Linkage:** This graph, identified as Figure A1-1, provides the generic transfer function for determining bulk current injection test levels. The X-axis represents the frequency in Megahertz (MHz) of the High-Intensity Radiated Field (HIRF) environment, while the Y-axis represents the normalized bulk current injection in milliamperes per Volt per meter (mA/V/m). The plotted line illustrates how the normalized bulk current injection varies with frequency for aeroplanes with a fuselage length of 25 meters or less. For instance, the graph shows that at 3 MHz and 15 MHz, the normalized transfer function value is 0.7 mA/V/m, and at 400 MHz, it is 0.3 mA/V/m. These values are intended to be linearly multiplied by the actual external HIRF environment (in V/m) to derive the required bulk current injection test level (in mA).](file_wSyEACTCE2d/image065.png)

Generic transfer function normalised to
1 V/m for an aeroplane with a fuselage length of ≤ 25 m.

Figure A1-2 — Generic transfer function — Aeroplane

![Aviation.Bot AI suggestion, not from EASA source: A logarithmic plot illustrating a generic transfer function, normalized to 1 V/m, for an aeroplane with a fuselage length greater than 25 meters and less than or equal to 50 meters.

Detailed Description:
The image displays a two-dimensional line graph on a white background, enclosed by a thick black border. The graph features a grid with both major and minor dotted lines, indicating a logarithmic scale for both axes.

The horizontal axis (X-axis) is labeled "Frequency - MHz" and uses a logarithmic scale ranging from 0.01 to 1000. Major tick marks and corresponding numerical labels are present at 0.01, 0.1, 1, 10, 100, and 1000.
The vertical axis (Y-axis) is labeled "mA/V/m" and also uses a logarithmic scale, ranging from 0.01 to 1. Major tick marks and corresponding numerical labels are present at 0.01, 0.1, and 1.

A prominent blue line represents the generic transfer function. This line is composed of three linear segments connecting four distinct data points, each marked by a solid blue circular marker.
1.  The first segment originates from the bottom-left corner of the plotted area, at the coordinates (0.01 MHz, 0.01 mA/V/m).
2.  This segment ascends linearly to the first explicitly labeled data point, located at (1.5 MHz, 0.7 mA/V/m). The label "1.5, 0.7" is positioned above and slightly to the right of this point.
3.  The second segment extends horizontally from (1.5 MHz, 0.7 mA/V/m) to the second explicitly labeled data point, located at (6 MHz, 0.7 mA/V/m). The label "6, 0.7" is positioned above and slightly to the right of this point.
4.  The third segment descends linearly from (6 MHz, 0.7 mA/V/m) to the final explicitly labeled data point, located at (400 MHz, 0.15 mA/V/m). The label "400, 0.15" is positioned below and slightly to the right of this point.

The graph's main title, positioned below the X-axis, reads "Figure A1-2 — Generic transfer function — Aeroplane". Below this title, a subtitle reads "Generic transfer function normalised to 1 V/m for an aeroplane with a fuselage length of > 25 m and ≤ 50 m."

Contextual Linkage:
This graph visually represents the relationship between frequency (in MHz) and a normalized transfer function (in mA/V/m) for a specific category of aeroplanes. The Y-axis values, representing mA/V/m, are intended to be multiplied by an external HIRF environment value (in V/m) to determine bulk current injection test levels. For instance, at 3 MHz, the graph shows a transfer function value of approximately 0.7 mA/V/m, which, if multiplied by a 100 V/m HIRF environment, would yield a 70 mA test level. The graph defines specific breakpoints at 1.5 MHz, 6 MHz, and 400 MHz, indicating changes in the transfer function's behavior across different frequency ranges.](file_wSyEACTCE2d/image066.png)

Generic transfer function normalised to
1 V/m for an aeroplane with a fuselage length of > 25 m and ≤ 50 m.

Figure A1-3 — Generic transfer function — Aeroplane

![Aviation.Bot AI suggestion, not from EASA source: The image displays a log-log line graph illustrating a generic transfer function, normalized to 1 V/m, for an aeroplane with a fuselage length greater than 50 meters, showing the relationship between frequency and bulk current injection test levels.

Detailed Description:
The image presents a two-dimensional line graph plotted on a grid with logarithmic scales for both the horizontal (x) and vertical (y) axes.
The horizontal axis is labeled "Frequency - MHz" and ranges from 0.01 MHz to 1000 MHz. Major tick marks are present at 0.01, 0.1, 1, 10, 100, and 1000 MHz.
The vertical axis is labeled "mA/V/m" and ranges from 0.01 mA/V/m to 10 mA/V/m. Major tick marks are present at 0.01, 0.1, 1, and 10 mA/V/m.
A fine grid of dotted lines covers the entire plotting area, corresponding to logarithmic subdivisions on both axes.

A solid blue line represents the generic transfer function, connecting five distinct data points, each marked by a solid blue circle.
1.  The curve originates at the bottom-left of the graph, approximately at coordinates (0.01 MHz, 0.04 mA/V/m).
2.  The first segment of the blue line ascends from the origin to a point explicitly labeled "0.5, 2.5". This point is located at 0.5 MHz on the frequency axis and 2.5 mA/V/m on the transfer function axis.
3.  The second segment is a horizontal line, indicating a constant transfer function value, extending from the point (0.5 MHz, 2.5 mA/V/m) to a point explicitly labeled "5, 2.5". This point is located at 5 MHz on the frequency axis and 2.5 mA/V/m on the transfer function axis.
4.  The third segment of the blue line descends from the point (5 MHz, 2.5 mA/V/m) to a point explicitly labeled "50, 0.3". This point is located at 50 MHz on the frequency axis and 0.3 mA/V/m on the transfer function axis.
5.  The fourth and final segment of the blue line descends from the point (50 MHz, 0.3 mA/V/m) to a point explicitly labeled "400, 0.15". This point is located at 400 MHz on the frequency axis and 0.15 mA/V/m on the transfer function axis. The plotted line terminates at this point within the visible graph boundaries.

Contextual Linkage:
This graph visually defines a generic transfer function that relates the frequency of an electromagnetic field to the resulting bulk current injection test level, normalized per unit of external electric field strength (1 V/m). The curve illustrates how this normalized current varies across a wide range of frequencies, showing an initial increase, a plateau at the maximum value, and then a subsequent decrease, providing specific coordinate pairs for key points along this function.](file_wSyEACTCE2d/image067.png)

Generic transfer function normalised to
1 V/m for an aeroplane with a fuselage length of > 50 m.

Figure A1-4 — Generic transfer function — Rotorcraft

![Aviation.Bot AI suggestion, not from EASA source: The image displays a log-log line graph illustrating the generic transfer function, normalized to 1 V/m, for a rotorcraft, showing the relationship between frequency and the bulk current injection test level.

Detailed Description:
The image presents a two-dimensional line graph with logarithmic scales on both the horizontal (X) and vertical (Y) axes, set against a grid of dotted lines.

The horizontal axis is labeled "Frequency - MHz" and ranges from 0.01 MHz to 1000 MHz. Major tick marks are present at 0.01, 0.1, 1, 10, 100, and 1000 MHz. Intermediate minor tick marks are also present, indicating subdivisions within each decade (e.g., 0.02, 0.03, ..., 0.09).

The vertical axis is labeled "mA/V/m" and ranges from 0.01 mA/V/m to 10 mA/V/m. Major tick marks are present at 0.01, 0.1, 1, and 10 mA/V/m. Intermediate minor tick marks are also present, indicating subdivisions within each decade.

A blue line plot, representing the generic transfer function, is drawn across the graph. This line is composed of three distinct linear segments on the log-log scale, connecting four key points, three of which are explicitly labeled with their coordinates and marked with blue circular data points:
1.  The line originates at the leftmost edge of the plot, approximately at a frequency of 0.01 MHz and a transfer function value of 0.025 mA/V/m.
2.  The first marked data point is at coordinates (5, 1.5), indicating a frequency of 5 MHz and a transfer function value of 1.5 mA/V/m. The line segment from the origin to this point shows an increasing trend.
3.  The second marked data point is at coordinates (30, 1.5), indicating a frequency of 30 MHz and a transfer function value of 1.5 mA/V/m. The line segment between 5 MHz and 30 MHz is horizontal, indicating a constant transfer function value of 1.5 mA/V/m.
4.  The third marked data point is at coordinates (400, 0.5), indicating a frequency of 400 MHz and a transfer function value of 0.5 mA/V/m. The line segment from 30 MHz to 400 MHz shows a decreasing trend.

The dotted grid lines extend from both major and minor tick marks across the entire plotting area, forming a fine mesh that aids in reading values from the graph.

Contextual Linkage:
The graph visually represents the generic transfer function for a rotorcraft, showing how the ratio of bulk current injection (in milliamperes) to the external HIRF environment electric field strength (in Volts per meter) varies with frequency. The Y-axis value (mA/V/m) can be multiplied by the external HIRF environment's electric field strength (in V/m) at a given frequency (X-axis) to determine the required bulk current injection test level.](file_wSyEACTCE2d/image068.png)

Generic transfer function normalised to
1 V/m for a rotorcraft.

Figure A1-5 — Generic transfer function — All aircraft

![Aviation.Bot AI suggestion, not from EASA source: The image displays a log-log graph illustrating a generic transfer function, normalized to 1 V/m, for all aircraft types, showing the relationship between frequency and the transfer function value in mA/V/m.

Detailed Description:
The image presents a two-dimensional graph with a white background and a black border. The graph features a logarithmic scale on both the horizontal (X) and vertical (Y) axes, overlaid with a grid of fine dotted lines.

The horizontal axis is labeled "Frequency - MHz" and ranges from 0.01 MHz on the left to 1000 MHz on the right. Major tick marks and corresponding labels are present at 0.01, 0.1, 1, 10, 100, and 1000 MHz.

The vertical axis is labeled "mA/V/m" and ranges from 0.01 mA/V/m at the bottom to 10 mA/V/m at the top. Major tick marks and corresponding labels are present at 0.01, 0.1, 1, and 10 mA/V/m.

A solid blue line, representing the generic transfer function, is plotted on the graph. This line is composed of several linear segments connecting distinct circular data points. The coordinates of five of these data points are explicitly labeled on the graph:
1.  The first labeled point is "0.5, 2.5", indicating a frequency of 0.5 MHz and a transfer function value of 2.5 mA/V/m.
2.  The second labeled point is "5, 2.5", indicating a frequency of 5 MHz and a transfer function value of 2.5 mA/V/m.
3.  The third labeled point is "10, 1.5", indicating a frequency of 10 MHz and a transfer function value of 1.5 mA/V/m.
4.  The fourth labeled point is "30, 1.5", indicating a frequency of 30 MHz and a transfer function value of 1.5 mA/V/m.
5.  The fifth labeled point is "400, 0.5", indicating a frequency of 400 MHz and a transfer function value of 0.5 mA/V/m.

The blue line starts at the bottom-left of the graph, approximately at (0.01 MHz, 0.04 mA/V/m), and ascends diagonally to the point (0.5 MHz, 2.5 mA/V/m). It then proceeds horizontally to the right to the point (5 MHz, 2.5 mA/V/m). Following this, it descends diagonally to the point (10 MHz, 1.5 mA/V/m). The line then continues horizontally to the right to the point (30 MHz, 1.5 mA/V/m). Finally, it descends diagonally to the right, ending at the point (400 MHz, 0.5 mA/V/m).

Contextual Linkage:
This graph visually defines a generic transfer function, which is a critical parameter for determining bulk current injection test levels. The Y-axis value (mA/V/m) represents the current generated per unit of electric field strength, normalized to a 1 V/m external High-Intensity Radiated Field (HIRF) environment. The X-axis represents the frequency of the HIRF. The plotted line illustrates how this normalized transfer function value changes across a broad frequency range, providing specific values at key frequency points for use in calculations.](file_wSyEACTCE2d/image069.png)

Generic transfer function normalised to
1 V/m for all aircraft.

Figure A1-6 — Generic attenuation values — All aircraft 100
MHz to 18 GHz

![Aviation.Bot AI suggestion, not from EASA source: The image displays a 2D line graph illustrating five distinct generic attenuation values in decibels (dB) as a function of frequency in gigahertz (GHz), applicable across a broad frequency range for all aircraft.

Detailed Description:
The image is a two-dimensional line graph with a white background and a light gray grid.
The vertical axis, labeled "Attenuation (dB)", is a linear scale ranging from 0 to 35 dB. Major tick marks are present at 5 dB intervals (0, 5, 10, 15, 20, 25, 30, 35), with minor tick marks at 1 dB intervals.
The horizontal axis, labeled "Frequency - GHz", is a logarithmic scale ranging from 0.1 GHz to 100 GHz. Major tick marks are present at 0.1, 1, 10, and 100 GHz.
Dotted grid lines extend horizontally from each major and minor tick on the vertical axis and vertically from each major and minor tick on the horizontal axis.

Five horizontal lines are plotted on the graph, each representing a constant attenuation value across the entire displayed frequency range (0.1 GHz to 100 GHz). Each line has a marker at its starting point (0.1 GHz) and another marker at approximately 18 GHz, with a text label indicating its specific attenuation value positioned to the right of the line.

The lines are described from bottom to top:
1. **0 dB Attenuation:** A gray dashed line with small, evenly spaced dashes. It has a gray diamond marker at 0.1 GHz and another gray diamond marker at approximately 18 GHz. The text label "0 dB" is positioned to its right.
2. **6 dB Attenuation:** A black dash-dot line (alternating long dashes and dots). It has a black square marker at 0.1 GHz and another black square marker at approximately 18 GHz. The text label "6 dB" is positioned to its right.
3. **12 dB Attenuation:** A solid blue line. It has a blue triangle marker at 0.1 GHz and another blue triangle marker at approximately 18 GHz. The text label "12 dB" is positioned to its right.
4. **20 dB Attenuation:** A dark blue dashed line with long, evenly spaced dashes. It has a dark blue 'x' marker at 0.1 GHz and another dark blue 'x' marker at approximately 18 GHz. The text label "20 dB" is positioned to its right.
5. **32 dB Attenuation:** A solid orange line. It has an orange 'x' marker at 0.1 GHz and another orange 'x' marker at approximately 18 GHz. The text label "32 dB" is positioned to its right.

Contextual Linkage: This graph visually presents five predefined generic attenuation values (0 dB, 6 dB, 12 dB, 20 dB, and 32 dB) that are constant across the frequency range from 0.1 GHz to 100 GHz. These values are intended for use in determining internal HIRF environments for aircraft, as indicated by the "Attenuation (dB)" and "Frequency - GHz" axis labels.](file_wSyEACTCE2d/image070.png)

[Amdt 20/13]

Appendix 1 to AMC 20-158 Generic transfer functions and attenuation

ED Decision 2015/017/R

1. Generic transfer functions

a. Suitable transfer functions for calculating the bulk current injection test levels for Level A display systems (see paragraph 9.k.) are given in Figures A1-1 through A1-5. These are derived generic transfer functions acquired from test results obtained from a significant number of aircraft. The test results were then processed to establish a 95 per cent population probability.

b. The transfer functions are normalised to a 1 V/m HIRF environment and may be multiplied linearly by the external HIRF environment to establish the bulk current injection test level requirements in the frequency range from 10 kHz up to 400 MHz. For example, if the HIRF environment is 100 V/m at 3 MHz, then using Figure A1-1, multiply 0.7 mA/V/m by 100 V/m to establish a test level of 70 milliamperes (mA).

c. Consult the User’s Guide (SAE ARP 5583A/EUROCAE ED-107A) for details on the use of generic transfer functions.

2. Generic attenuation

a. Figure A1-6 shows the generic attenuation for frequencies from 100 MHz to 18 GHz that can be used for determining the internal HIRF environment where equipment and associated wiring for Level A display systems (see paragraph 9.k.) are installed. This internal HIRF environment provides the test level for the integrated system radiated susceptibility laboratory test. The external HIRF environment should be divided by the appropriate attenuation, in linear units, to determine the internal HIRF environment. For example, 12 dB or a 4:1 attenuation means the test level is the applicable external HIRF environment electric field strength reduced by a factor of 4.

b. Guidance on the use of the generic attenuation is given below.

1. No attenuation. No attenuation credit can be used when the Level A display equipment and associated wiring are located in aircraft areas with no HIRF shielding, such as areas with unprotected non-conductive composite structures, areas where there is no guarantee of structural bonding, or other open areas where no shielding is provided. The applicant may choose to use no attenuation for equipment that may be installed in a broad range of aircraft areas.

2. 6 dB attenuation. This attenuation is appropriate when the Level A display equipment and associated wiring are located in aircraft areas with minimal HIRF shielding, such as a cockpit in a non-conductive composite fuselage with minimal additional shielding, or areas on the wing leading or trailing edges, or in wheel wells.

3. 12 dB attenuation. This attenuation is appropriate when the Level A display equipment and associated wiring are located entirely within aircraft areas with some HIRF shielding, in aircraft with a metal fuselage or a composite fuselage with shielding effectiveness equivalent to metal. Examples of such areas are avionics bays not enclosed by bulkheads, cockpits, and areas near windows, access panels, and doors without EMI gaskets. Current-carrying conductors in this area, such as hydraulictubing, control cables, wire bundles, and metal wire trays, are not all electrically bonded to bulkheads they pass through.

4. 20 dB attenuation. This attenuation is appropriate when the Level A display equipment and associated wiring are located entirely within the aircraft areas with moderate HIRF shielding, in aircraft with a metal fuselage or a composite fuselage with shielding effectiveness equivalent to metal. In addition, wire bundles passing through bulkheads in these areas have shields electrically bonded to the bulkheads. Wire bundles are installed close to metal structure and take advantage of other inherent shielding characteristics provided by metal structure. Current-carrying conductors such as hydraulic tubing, cables, and metal wire trays are electrically bonded to all bulkheads they pass through.

5. 32 dB attenuation. This attenuation is appropriate when the Level A display equipment and all associated wiring to and from equipment are located entirely within areas with very effective HIRF shielding to form an electromagnetic enclosure.

c. Different attenuation values may be appropriate for different frequency ranges. For example, 0 dB attenuation may be used for the frequency range of 100 MHz to 400 MHz, 6 dB attenuation for the frequency range of 400 MHz to 1 GHz, and 12 dB attenuation for the frequency range of 1 GHz to 18 GHz. If the applicant intends to use different attenuation values for various frequency ranges, then the supporting rationale should also be provided.

d. Consult the User’s Guide for details on the use of generic attenuation.

3. Measured transfer functions or attenuation. The applicant can produce their own generic transfer functions and attenuation for their Level A display systems (see paragraph 9.k.) based on actual measurements on their aircraft models. These transfer functions and attenuation can then be used in their HIRF compliance submission in place of the generic transfer functions and attenuation specified in this appendix. The Agency encourages this approach because it provides a more accurate reflection of the true internal HIRF environment of the aircraft models. However, if the applicant intends to produce their own generic transfer functions and attenuation, then this approach should also be addressed in the HIRF compliance plan (see paragraph 8.a.) that is submitted to the Agency for approval.

Figure A1-1 — Generic transfer function — Aeroplane

![EASA EAR image](/static/files/file_ftLzkYEblJP/image066.png)

Generic transfer function normalised to 1 V/m for an aeroplane with a fuselage length of ≤ 25 m.

Figure A1-2 — Generic transfer function — Aeroplane

![EASA EAR image](/static/files/file_ftLzkYEblJP/image067.png)

Generic transfer function normalised to 1 V/m for an aeroplane with a fuselage length of > 25 m and ≤ 50 m.

Figure A1-3 — Generic transfer function — Aeroplane

![EASA EAR image](/static/files/file_ftLzkYEblJP/image068.png)

Generic transfer function normalised to 1 V/m for an aeroplane with a fuselage length of > 50 m.

Figure A1-4 — Generic transfer function — Rotorcraft

![EASA EAR image](/static/files/file_ftLzkYEblJP/image069.png)

Generic transfer function normalised to 1 V/m for a rotorcraft.

Figure A1-5 — Generic transfer function — All aircraft

![EASA EAR image](/static/files/file_ftLzkYEblJP/image070.png)

Generic transfer function normalised to 1 V/m for all aircraft.

Figure A1-6 — Generic attenuation values — All aircraft 100 MHz to 18 GHz

![EASA EAR image](/static/files/file_ftLzkYEblJP/image071.png)

[Amdt 20/13]

Compare / EASA/ Incorporated Amendments/ Compare & Highlight Differences

Appendix 1 to AMC 20-158 Generic transfer functions and attenuation

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