Appendix C to AMC 20-21 Determination if a major change to an aircraft should be specifically subjected to an EZAP

• ED Decision 2008/007/R found in: AMC-20 Amdt 21 - Airworthiness of Products, Parts and Appliances (Apr 2021)

Appendix C to AMC 20-21 Determination if a major change to an aircraft should be specifically subjected to an EZAP ED Decision 2008/007/R The EZAP provides a means for TC and STC holders to develop improvements to EWIS maintenance programs. These improvements will be in the form of new inspections and other tasks designed to prevent significant accumulation of combustible materials on or adjacent to EWIS components that would be added to the Instructions for Continued Airworthiness or Service Bulletins (SB) for the aircraft and STC. While TC holders are required to conduct the EZAP for all zones in an aircraft, it may be determined that EZAP for an SB or STC is not necessary where the modification does not appreciably affect the zones where it is installed. The “Determination if SB modification or STC requires EZAP” procedure was developed to identify modifications that sufficiently affect zone attributes to warrant re-application of EZAP to the entire zone. This logic assumes that the aircraft TC holder has accomplished the EZAP on each zone of the aircraft without consideration of the SB modification or STC installation. The objective of this analysis is to assess whether the modification itself has affected wiring or certain zone attributes that could change the outcome of the EZAP performed by the aircraft TC holder. The determination if the SB or STC requires EZAP, and re-application of the EZAP to SB or STC affected zones, is the responsibility of the respective holder of the SB or STC. It is expected that the TC and STC holders will collaborate with each other and operators as necessary to obtain information required to conduct the analysis. The TC or STC holder should communicate the results of the procedure, including the cases when no new tasks are identified. The method of communication may be via SB, Service Letter, ICAW Revision, or other means acceptable to EASA. In situations where a previously installed STC is no longer supported by a viable STC holder (e.g. STC holder defunct), the responsibility for determining if the STC requires EZAP, and re-application of EZAP to any affected zones, is assigned to the individual operators who utilise the STC on their aircraft. In cases where the operator does not have experience in application of analytical logic processes, it will be necessary for the operator to gain competence in, or seek external assistance in conducting the analysis. A record of the outcome of operator accomplished analysis for STC (even if no tasks are identified) should be permanently retained by the operator. A copy of the record should be included in the aircraft records normally transferred upon change of aircraft operator. The attached logic chart provides a means to assess whether an SB modification or STC has sufficiently affected wiring or certain other zone attributes as to require reapplication of the EZAP to the entire zone with consideration of the modification present. The section following the chart provides detailed explanations of each step in the “Determination if SB modification or STC requires EZAP” with appropriate examples. It is recommended that, where possible, the analyst should utilise the availability of actual aircraft to ensure they fully understand the zones being analysed. Specifically, it must be determined how installation of the modification could affect zone attributes such as density, environment, proximity of wiring to primary and back-up flight controls, presence of combustible materials, and potential for accidental damage to wiring. Appendix C. Figure 1. Determination if SB modification or STC requires EZAP ![Aviation.Bot AI suggestion, not from EASA source: The image displays a flowchart detailing the procedure for determining if a Supplemental Type Certificate (STC) modification requires an Electrical Wiring Interconnection System (EWIS) Zone Analysis Procedure (EZAP). Detailed Description: The image presents a flowchart composed of six distinct elements: two diamond-shaped decision nodes and four rectangular process/result nodes, interconnected by directional arrows. All elements are white with black borders and black text. 1. **Top Decision Node (Diamond):** This is the starting point of the flowchart, labeled with the number "1" at the top center. The text inside this diamond reads: "Does the STC: - affect or modify wiring or its environment - install or result in wiring being located within 5 cm (2 inches) of both primary & backup hydraulic, mechanical, or electrical flight controls - change the density of the zone, or - change the potential effects of fire in the zone?". * An arrow labeled "NO" extends horizontally to the right from the right vertex of this diamond. * An arrow labeled "YES" extends vertically downwards from the bottom vertex of this diamond. 2. **Right Process Node (Rectangle):** Located to the right of the top decision node, connected by the "NO" arrow. It is labeled with the number "2" at the top center. The text inside this rectangle reads: "No further action required". 3. **Middle Process Node (Rectangle):** Located directly below the top decision node, connected by the "YES" arrow. It is labeled with the number "3" at the top center. The text inside this rectangle reads: "Perform EZAP analysis". * An unlabeled arrow extends vertically downwards from the bottom center of this rectangle. 4. **Lower Decision Node (Diamond):** Located directly below the middle process node, connected by the unlabeled downward arrow. It is labeled with the number "4" at the top center. The text inside this diamond reads: "Determine if there is an existing MRBR EZAP task(s) that is applicable and effective?". * An arrow labeled "YES" extends horizontally to the right from the right vertex of this diamond. * An arrow labeled "NO" extends vertically downwards from the bottom vertex of this diamond. 5. **Lower Right Process Node (Rectangle):** Located to the right of the lower decision node, connected by the "YES" arrow. It is labeled with the number "5" at the top center. The text inside this rectangle reads: "No further action required because the existing EZAP derived maintenance task is adequate". 6. **Bottom Process Node (Rectangle):** Located directly below the lower decision node, connected by the "NO" arrow. It is labeled with the number "6" at the top center. The text inside this rectangle reads: "Develop appropriate task and incorporate it into existing maintenance program". Contextual Linkage: The flowchart illustrates a decision-making process. It begins by evaluating the impact of an STC on aircraft wiring and zone attributes (Node 1). If there is no significant impact, no further action is required (Node 2). If there is a significant impact, an EZAP analysis must be performed (Node 3). Following the EZAP analysis, the process determines if existing Maintenance Review Board Report (MRBR) EZAP tasks are sufficient (Node 4). If existing tasks are adequate, no further action is needed regarding new tasks (Node 5). If existing tasks are not adequate, new tasks must be developed and integrated into the maintenance program (Node 6). "mermaid graph TD A{1. Does the STC: - affect or modify wiring or its environment - install or result in wiring being located within 5 cm (2 inches) of both primary & backup hydraulic, mechanical, or electrical flight controls - change the density of the zone, or - change the potential effects of fire in the zone?} B[2. No further action required] C[3. Perform EZAP analysis] D{4. Determine if there is an existing MRBR EZAP task(s) that is applicable and effective?} E[5. No further action required because the existing EZAP derived maintenance task is adequate] F[6. Develop appropriate task and incorporate it into existing maintenance program] A -- "NO" --> B A -- "YES" --> C C --> D D -- "YES" --> E D -- "NO" --> F "](file_wSyEACTCE2d/image034-b.png) Explanation of Steps Step 1:           Does the SB or STC affect or modify wiring or it’s environment? The question asks whether the STC affects or modifies wiring. Modifications to wiring or other EWIS components include, but are not limited to removal, addition, relocation, etc. Does the SB or STC install or result in wiring being located within 5 cm (2 inches) of primary and back-up hydraulic, mechanical or electric flight controls, change the density of the zone or change the potential effects of fire in the zone? Does the SB or STC affect zone density? If the STC includes the addition or deletion of numerous components in a small area, the density of the zone could be changed even if wire bundles are untouched. A significant change in the zone density should warrant re-analysis of the zone. Potential effects of fire on adjacent wiring and systems require the analyst to assess the potential effect of a localised fire on adjacent wiring and systems by considering the potential for loss of multiple functions to the extent that a hazard could be introduced. Consideration of potential effect must also include whether wiring is in close proximity (i.e. within 5 cm (2 inches)) to both primary and back-up flight controls. Additionally, this question requires an evaluation of whether the zone might contain combustible material that could cause a fire to be sustained in the event of an ignition source arising in adjacent wiring. Examples include the possible presence of fuel vapours, dust/lint accumulation, and contaminated insulation blankets. With respect to commonly used liquids (e.g. oils, hydraulic fluids, and corrosion prevention compounds), the analyst should refer to the product specification in order to assess the potential for combustibility. The product may be readily combustible only in vapour/mist form and thus an assessment is required to determine if conditions might exist in the zone for the product to be in this state. Although liquid contamination of wiring by most synthetic oil and hydraulic fluids (e.g. skydrol) may not be considered combustible, it is a cause for concern if it occurs in a zone where contamination causes significant adherence of dust and lint. If the answer to this question is ‘No’, then no further action is required (Step 2), since the density of the zone or the potential effects of fire in the zone has not changed. Step 2:           No further action is required. Step 3:            Perform an EZAP analysis. If the answer to question 1 is ‘Yes’, then the only way to determine if existing EWIS maintenance tasks are sufficient is to perform the EZAP for the SB or STC and compare the results with the existing EWIS maintenance tasks (see Step 4). Step 4:           Is there an existing MRBR EZAP task(s) that is applicable and effective? Once the SB or STC EZAP has been accomplished, a comparison of the derived maintenance tasks can be made with the existing EWIS maintenance tasks. If the existing tasks are adequate, then no further action regarding EWIS maintenance actions for the STC is necessary. Step 5:            No further action is required since the existing EZAP-derived maintenance task is adequate. Step 6:            Develop an appropriate task and incorporate it into the existing maintenance programme. These tasks should be incorporated into the operator’s existing maintenance programme. [Amdt 20/4] Appendix C to AMC 20-21 Determination if a major change to an aircraft should be specifically subjected to an EZAP ED Decision 2008/007/R The EZAP provides a means for TC and STC holders to develop improvements to EWIS maintenance programs. These improvements will be in the form of new inspections and other tasks designed to prevent significant accumulation of combustible materials on or adjacent to EWIS components that would be added to the Instructions for Continued Airworthiness or Service Bulletins (SB) for the aircraft and STC. While TC holders are required to conduct the EZAP for all zones in an aircraft, it may be determined that EZAP for an SB or STC is not necessary where the modification does not appreciably affect the zones where it is installed. The “Determination if SB modification or STC requires EZAP” procedure was developed to identify modifications that sufficiently affect zone attributes to warrant re-application of EZAP to the entire zone. This logic assumes that the aircraft TC holder has accomplished the EZAP on each zone of the aircraft without consideration of the SB modification or STC installation. The objective of this analysis is to assess whether the modification itself has affected wiring or certain zone attributes that could change the outcome of the EZAP performed by the aircraft TC holder. The determination if the SB or STC requires EZAP, and re-application of the EZAP to SB or STC affected zones, is the responsibility of the respective holder of the SB or STC. It is expected that the TC and STC holders will collaborate with each other and operators as necessary to obtain information required to conduct the analysis. The TC or STC holder should communicate the results of the procedure, including the cases when no new tasks are identified. The method of communication may be via SB, Service Letter, ICAW Revision, or other means acceptable to EASA. In situations where a previously installed STC is no longer supported by a viable STC holder (e.g. STC holder defunct), the responsibility for determining if the STC requires EZAP, and re-application of EZAP to any affected zones, is assigned to the individual operators who utilise the STC on their aircraft. In cases where the operator does not have experience in application of analytical logic processes, it will be necessary for the operator to gain competence in, or seek external assistance in conducting the analysis. A record of the outcome of operator accomplished analysis for STC (even if no tasks are identified) should be permanently retained by the operator. A copy of the record should be included in the aircraft records normally transferred upon change of aircraft operator. The attached logic chart provides a means to assess whether an SB modification or STC has sufficiently affected wiring or certain other zone attributes as to require reapplication of the EZAP to the entire zone with consideration of the modification present. The section following the chart provides detailed explanations of each step in the “Determination if SB modification or STC requires EZAP” with appropriate examples. It is recommended that, where possible, the analyst should utilise the availability of actual aircraft to ensure they fully understand the zones being analysed. Specifically, it must be determined how installation of the modification could affect zone attributes such as density, environment, proximity of wiring to primary and back-up flight controls, presence of combustible materials, and potential for accidental damage to wiring. Appendix C. Figure 1. Determination if SB modification or STC requires EZAP ![Aviation.Bot AI suggestion, not from EASA source: This image presents a flowchart detailing the decision-making process to determine if a Service Bulletin (SB) modification or Supplemental Type Certificate (STC) requires an Electrical Wiring Interconnection System (EWIS) Zone Analysis Procedure (EZAP). Detailed Description: The image displays a flowchart with six distinct steps, represented by a combination of diamond (decision) and rectangular (process/action) shapes, connected by solid black arrows. 1. **Step 1 (Decision):** Located at the top center, this is a large diamond-shaped box labeled "1". The text inside asks: "Does the STC:\n- affect or modify wiring or its environment\n- install or result in wiring being located\nwithin 5 cm (2 inches) of both primary & backup hydraulic,\nmechanical, or\nelectrical flight controls\n- change the density of the zone, or\n- change the potential effects of fire in the zone?". * An arrow labeled "NO" extends horizontally to the right from the right vertex of this diamond. * An arrow labeled "YES" extends vertically downwards from the bottom vertex of this diamond. 2. **Step 2 (Action):** Located to the right of Step 1, this is a rectangular box labeled "2". The text inside states: "No further action required". This box serves as a terminal point in the flowchart. 3. **Step 3 (Action):** Located directly below Step 1, this is a rectangular box labeled "3". The text inside states: "Perform EZAP analysis". * A vertical arrow extends downwards from the bottom of this rectangle. 4. **Step 4 (Decision):** Located directly below Step 3, this is a diamond-shaped box labeled "4". The text inside asks: "Determine if there is an existing\nMRBR EZAP task(s) that is\napplicable and effective?". * An arrow labeled "YES" extends horizontally to the right from the right vertex of this diamond. * An arrow labeled "NO" extends vertically downwards from the bottom vertex of this diamond. 5. **Step 5 (Action):** Located to the right of Step 4, this is a rectangular box labeled "5". The text inside states: "No further action required because the existing\nEZAP derived maintenance task is adequate". This box serves as a terminal point in the flowchart. 6. **Step 6 (Action):** Located directly below Step 4, this is a rectangular box labeled "6". The text inside states: "Develop appropriate task and incorporate it into\nexisting maintenance program". This box serves as a terminal point in the flowchart. Contextual Linkage: The flowchart outlines a sequential process for evaluating the impact of an SB or STC on aircraft wiring and its environment, specifically concerning the need for an EZAP. The process begins with an initial assessment (Step 1) of whether the modification impacts wiring, its proximity to flight controls, zone density, or fire potential. A "NO" answer leads to immediate conclusion (Step 2). A "YES" answer necessitates performing an EZAP analysis (Step 3). Following the EZAP analysis, a determination is made (Step 4) regarding the applicability and effectiveness of existing Maintenance Review Board Report (MRBR) EZAP tasks. If existing tasks are sufficient ("YES"), no further action is required (Step 5). If existing tasks are not sufficient ("NO"), new tasks must be developed and integrated into the maintenance program (Step 6). "mermaid graph TD 1{{"1<br>Does the STC:<br>- affect or modify wiring or its environment<br>- install or result in wiring being located<br>within 5 cm (2 inches) of both primary & backup hydraulic,<br>mechanical, or<br>electrical flight controls<br>- change the density of the zone, or<br>- change the potential effects of fire in the zone?"}} 2["2<br>No further action required"] 3["3<br>Perform EZAP analysis"] 4{{"4<br>Determine if there is an existing<br>MRBR EZAP task(s) that is<br>applicable and effective?"}} 5["5<br>No further action required because the existing<br>EZAP derived maintenance task is adequate"] 6["6<br>Develop appropriate task and incorporate it into<br>existing maintenance program"] 1 -- "NO" --> 2 1 -- "YES" --> 3 3 --> 4 4 -- "YES" --> 5 4 -- "NO" --> 6 "](file_tNNDI2wQkpg/image044.jpg) Explanation of Steps Step 1:           Does the SB or STC affect or modify wiring or it’s environment? The question asks whether the STC affects or modifies wiring. Modifications to wiring or other EWIS components include, but are not limited to removal, addition, relocation, etc. Does the SB or STC install or result in wiring being located within 5 cm (2 inches) of primary and back-up hydraulic, mechanical or electric flight controls, change the density of the zone or change the potential effects of fire in the zone? Does the SB or STC affect zone density? If the STC includes the addition or deletion of numerous components in a small area, the density of the zone could be changed even if wire bundles are untouched. A significant change in the zone density should warrant re-analysis of the zone. Potential effects of fire on adjacent wiring and systems require the analyst to assess the potential effect of a localised fire on adjacent wiring and systems by considering the potential for loss of multiple functions to the extent that a hazard could be introduced. Consideration of potential effect must also include whether wiring is in close proximity (i.e. within 5 cm (2 inches)) to both primary and back-up flight controls. Additionally, this question requires an evaluation of whether the zone might contain combustible material that could cause a fire to be sustained in the event of an ignition source arising in adjacent wiring. Examples include the possible presence of fuel vapours, dust/lint accumulation, and contaminated insulation blankets. With respect to commonly used liquids (e.g. oils, hydraulic fluids, and corrosion prevention compounds), the analyst should refer to the product specification in order to assess the potential for combustibility. The product may be readily combustible only in vapour/mist form and thus an assessment is required to determine if conditions might exist in the zone for the product to be in this state. Although liquid contamination of wiring by most synthetic oil and hydraulic fluids (e.g. skydrol) may not be considered combustible, it is a cause for concern if it occurs in a zone where contamination causes significant adherence of dust and lint. If the answer to this question is ‘No’, then no further action is required (Step 2), since the density of the zone or the potential effects of fire in the zone has not changed. Step 2:           No further action is required. Step 3:            Perform an EZAP analysis. If the answer to question 1 is ‘Yes’, then the only way to determine if existing EWIS maintenance tasks are sufficient is to perform the EZAP for the SB or STC and compare the results with the existing EWIS maintenance tasks (see Step 4). Step 4:           Is there an existing MRBR EZAP task(s) that is applicable and effective? Once the SB or STC EZAP has been accomplished, a comparison of the derived maintenance tasks can be made with the existing EWIS maintenance tasks. If the existing tasks are adequate, then no further action regarding EWIS maintenance actions for the STC is necessary. Step 5:            No further action is required since the existing EZAP-derived maintenance task is adequate. Step 6:            Develop an appropriate task and incorporate it into the existing maintenance programme. These tasks should be incorporated into the operator’s existing maintenance programme. [Amdt 20/4] Appendix C to AMC 20-21 Determination if a major change to an aircraft should be specifically subjected to an EZAP ED Decision 2008/007/R The EZAP provides a means for TC and STC holders to develop improvements to EWIS maintenance programs. These improvements will be in the form of new inspections and other tasks designed to prevent significant accumulation of combustible materials on or adjacent to EWIS components that would be added to the Instructions for Continued Airworthiness or Service Bulletins (SB) for the aircraft and STC. While TC holders are required to conduct the EZAP for all zones in an aircraft, it may be determined that EZAP for an SB or STC is not necessary where the modification does not appreciably affect the zones where it is installed. The “Determination if SB modification or STC requires EZAP” procedure was developed to identify modifications that sufficiently affect zone attributes to warrant re-application of EZAP to the entire zone. This logic assumes that the aircraft TC holder has accomplished the EZAP on each zone of the aircraft without consideration of the SB modification or STC installation. The objective of this analysis is to assess whether the modification itself has affected wiring or certain zone attributes that could change the outcome of the EZAP performed by the aircraft TC holder. The determination if the SB or STC requires EZAP, and re-application of the EZAP to SB or STC affected zones, is the responsibility of the respective holder of the SB or STC. It is expected that the TC and STC holders will collaborate with each other and operators as necessary to obtain information required to conduct the analysis. The TC or STC holder should communicate the results of the procedure, including the cases when no new tasks are identified. The method of communication may be via SB, Service Letter, ICAW Revision, or other means acceptable to EASA. In situations where a previously installed STC is no longer supported by a viable STC holder (e.g. STC holder defunct), the responsibility for determining if the STC requires EZAP, and re-application of EZAP to any affected zones, is assigned to the individual operators who utilise the STC on their aircraft. In cases where the operator does not have experience in application of analytical logic processes, it will be necessary for the operator to gain competence in, or seek external assistance in conducting the analysis. A record of the outcome of operator accomplished analysis for STC (even if no tasks are identified) should be permanently retained by the operator. A copy of the record should be included in the aircraft records normally transferred upon change of aircraft operator. The attached logic chart provides a means to assess whether an SB modification or STC has sufficiently affected wiring or certain other zone attributes as to require reapplication of the EZAP to the entire zone with consideration of the modification present. The section following the chart provides detailed explanations of each step in the “Determination if SB modification or STC requires EZAP” with appropriate examples. It is recommended that, where possible, the analyst should utilise the availability of actual aircraft to ensure they fully understand the zones being analysed. Specifically, it must be determined how installation of the modification could affect zone attributes such as density, environment, proximity of wiring to primary and back-up flight controls, presence of combustible materials, and potential for accidental damage to wiring. Appendix C. Figure 1. Determination if SB modification or STC requires EZAP  Explanation of Steps Step 1: Does the SB or STC affect or modify wiring or it’s environment? The question asks whether the STC affects or modifies wiring. Modifications to wiring or other EWIS components include, but are not limited to removal, addition, relocation, etc. Does the SB or STC install or result in wiring being located within 5 cm (2 inches) of primary and back-up hydraulic, mechanical or electric flight controls, change the density of the zone or change the potential effects of fire in the zone? Does the SB or STC affect zone density? If the STC includes the addition or deletion of numerous components in a small area, the density of the zone could be changed even if wire bundles are untouched. A significant change in the zone density should warrant re-analysis of the zone. Potential effects of fire on adjacent wiring and systems require the analyst to assess the potential effect of a localised fire on adjacent wiring and systems by considering the potential for loss of multiple functions to the extent that a hazard could be introduced. Consideration of potential effect must also include whether wiring is in close proximity (i.e. within 5 cm (2 inches)) to both primary and back-up flight controls. Additionally, this question requires an evaluation of whether the zone might contain combustible material that could cause a fire to be sustained in the event of an ignition source arising in adjacent wiring. Examples include the possible presence of fuel vapours, dust/lint accumulation, and contaminated insulation blankets. With respect to commonly used liquids (e.g. oils, hydraulic fluids, and corrosion prevention compounds), the analyst should refer to the product specification in order to assess the potential for combustibility. The product may be readily combustible only in vapour/mist form and thus an assessment is required to determine if conditions might exist in the zone for the product to be in this state. Although liquid contamination of wiring by most synthetic oil and hydraulic fluids (e.g. skydrol) may not be considered combustible, it is a cause for concern if it occurs in a zone where contamination causes significant adherence of dust and lint. If the answer to this question is ‘No’, then no further action is required (Step 2), since the density of the zone or the potential effects of fire in the zone has not changed. Step 2: No further action is required. Step 3: Perform an EZAP analysis. If the answer to question 1 is ‘Yes’, then the only way to determine if existing EWIS maintenance tasks are sufficient is to perform the EZAP for the SB or STC and compare the results with the existing EWIS maintenance tasks (see Step 4). Step 4: Is there an existing MRBR EZAP task(s) that is applicable and effective? Once the SB or STC EZAP has been accomplished, a comparison of the derived maintenance tasks can be made with the existing EWIS maintenance tasks. If the existing tasks are adequate, then no further action regarding EWIS maintenance actions for the STC is necessary. Step 5: No further action is required since the existing EZAP-derived maintenance task is adequate. Step 6: Develop an appropriate task and incorporate it into the existing maintenance programme. These tasks should be incorporated into the operator’s existing maintenance programme. [Amdt 20/4]