Appendix A of the criteria for considering task interval alignment is access requirements for the zone. Task intervals should be aligned to the maximum extent possible so undue disturbance of EWIS and other systems located within the zone does not occur. If a task is aligned with an existing zonal inspection, it must be identified as an EZAP-related task to prevent the possibility that it could be deleted or inappropriately escalated.
• Stand-alone GVIs and DETs identified by the EZAP should not be consolidated into the ZIP. They must be introduced and retained as dedicated tasks in the scheduled maintenance program under ATA 20 (the ATA category for electrical wiring), or ATA 28 in the case of combined SFAR 88 and EWIS inspection tasks. These tasks, along with tasks identified to reduce accumulation of combustible materials (known as cleaning or restoration tasks), should be uniquely identified to ensure they are not consolidated into the zonal program or deleted during future program development.
Within Maintenance-Steering-Group-3-based MRBRs, these may be introduced under ATA 20 with no failure effect category assigned. While a stand-alone GVI and a DET cannot be combined with existing zonal inspections, the intervals for performing them should be aligned with other maintenance tasks in the zone, such as zonal GVIs, to the extent possible.
Note:
In the past, there has been some confusion about using existing zonal GVIs in lieu of EZAP- identified stand-alone GVIs. However, a zonal GVI does not satisfy the intent of a stand alone GVI. Although on the surface it may appear that the zonal GVI would accomplish the same inspection of the EWIS within a zone that a stand-alone GVI would, it does not. This is because the stand-alone GVI forces the maintenance technician to pay particular attention to the EWIS that is identified as being necessary to inspect. It is this particular attention that will help ensure that EWIS degradation issues are identified and corrected before a potential safety issue arises. While a zonal GVI is a recognized and effective inspection technique, it does not focus particular attention on EWIS or any other system or structural component within the zone and, therefore, cannot be used in lieu of a stand-alone GVI when the EZAP identifies a stand-alone GVI as necessary.
For programs without a ZIP:
Although some non-zonal inspection programs may already include some dedicated inspections of EWIS that may be equivalent to new tasks identified by an EZAP, it is expected that a significant number of new EWIS inspections will be identified for introduction as dedicated tasks in the system and powerplant program. All new tasks identified by an EZAP should be uniquely identified to ensure they are not deleted during future program development.
A-11
Appendix A For programs with or without a ZIP:
The following guide can be used for programs with or without a ZIP to determine proper consolidation between EZAP-derived inspections and existing inspections of the same item or area. When an EZAP task is selected for consolidation, the documentation should include a record identifying it for traceability purposes.
• If the EZAP inspection interval and existing inspection interval are equal, but the
inspection levels are different, the more detailed inspection takes precedence (for
example, a 1C DET takes precedence over a 1C GVI).
• If the EZAP inspection interval and existing inspection interval are different, but the inspection levels are equal, the more frequent inspection interval takes precedence (for example, a 1C GVI takes precedent over a 2C GVI).
• If the EZAP inspection interval and level are different than the existing inspection interval and level, these tasks may be consolidated using the more frequent inspection and at the more detailed level (for example, a 1C DET takes precedent over a 2C GVI). When the more frequent inspection is less detailed, the tasks should not be consolidated.
For EZAP-developed STC tasks, it may not be possible for the STC holder to determine whether a ZIP exists on specific airplane that will use the STC. If a ZIP exists, consolidation of EZAP-derived STC tasks into an operator’s ZIP will be the responsibility of the operator and should be approved by the operator’s FAA principal inspector or cognizant Flight Standards District Office (FSDO). AC 120-99, Incorporation of Electrical Wiring Interconnection System (EWIS) Instructions for Continued Airworthiness into an Operator’s Maintenance Program, will contain guidance related to this.
Note:
The more frequent inspection at the more detailed level should be used, unless it is judged that performing the more detailed inspection too frequently can result in stressing/disturbance of EWIS components.
In cases where the STC holder determines a requirement for a GVI that should not be consolidated into a ZIP, this stand-alone GVI should be specifically identified as such in the EZAP-derived ICA for the STC.
A-12
Appendix A
3. Examples of Typical EZAP Worksheets.
a. For Anyone Required to Conduct an EZAP Evaluation. The following pages contain worksheets you can use to conduct an EZAP. The first six worksheets contain notes to assist you in proper use of the worksheet. There are blank worksheets in appendix H of this AC that you can copy and use to conduct the analysis.
• EZAP Worksheet 1: Enhanced Zonal Analysis – Details of Zone
• EZAP Worksheet 2: Enhanced Zonal Analysis – Assessment of Zone Attributes
• EZAP Worksheet 3A – For Airplane Models with a Dedicated Zonal Inspection Program (ZIP): Enhanced Zonal Analysis – Inspection Level Determination Based on Zone Size, Density, and Potential Impact of Fire
• EZAP Worksheet 3B – For Programs without a Dedicated Zonal Inspection Program (ZIP): Enhanced Zonal Analysis – Inspection Level Determination Based on Zone Size, Density, and Potential Impact of Fire
• EZAP Worksheet 4 – Intervals Based on “A” and “C” Checks: Enhanced Zonal Analysis – Interval Determination Based on Hostility of Environment and Likelihood of Accidental Damage
• EZAP Worksheet 5: Enhanced Zonal Analysis – Task Summary A-13
EZAP WORKSHEET 1 05/04/10 Enhanced Zonal Analysis - Details of Zone (steps 1 and 2 of figure 1) Zone Number: Zone Description:
Hydraulic plumbing Comments Hydraulic component (valves, actuators, pumps) Pneumatic plumbing Pneumatic components (valves, actuators) EWIS - power feeder (high voltage, high amperage) EWIS - motor driven devices A-14 EWIS - instrumentation and monitoring Use this area to describe the zone location, access, and boundaries. List the content of the zone such as installed equipment, wiring, other EWIS EWIS - data bus components, plumbing, components. Also note significant EWIS related items. Examples: "Wire bundle routed within 2 inches of high-temperature Electrical components anti-ice ducting." or "Zone contains IDG, RAT, APU and forward galley Primary flight control mechanisms power feeder cables."
Secondary flight control mechanisms The intent of the description is to provide the analyst with a clear understanding of what is in the zone and how it could potentially affect Engine control mechanisms wiring and other EWIS components within the zone.
Fuel system components Insulation Oxygen system components Potable water system components Appendix A AC 25-27A Waste water system components
EZAP WORKSHEET 2 05/04/10 Enhanced Zonal Analysis - Assessment of Zone Attributes (steps 3 through 7 of figure 1) Zone Number: Zone Description:
Answers and Explanations NO (Notes: Steps 1 & 2 Completed on worksheet 1)
3. Does the zone No further action is contain EWIS? YES necessary
3.
If the answer to the questions contained in step 3 and step 7 is "NO," then no further analysis is necessary.
NO . Is wiring or other NO
4. Are there, or are there EWIS components If the answer to question 5 is "YES" and a task is J likely to be, close to both primary identified that can significantly reduce the ur combustibles in the YES AND back-up hydraulic, YES likelihood of accumulation of combustible zone? mechanical, or electrical materials, the task and interval must be defined in flight controls? step 6. If the task identified is a cleaning (restoration) task to remove dust/lint accumulation from wiring, other EWIS components, and/or other
5. items within the zone, the interval for the task must be frequent enough to keep the zone, including the
5. Is there an effective task to significantly NO 8. EWIS inspection tasks determination. of accumulation of dust/lint on the EWIS and other EWIS, relatively clean based on the expected rate reduce the likelihood of accumulation of YES See worksheets 3A and 3B components components within the zone.
combustible materials? In all cases, after step 5 and/or step 6, the analysis
6. is continued to step 8.
6. Define task and interval. List on Continue the analysis Appendix A AC 25-27A worksheet 5, Task Summary area
EZAP WORKSHEET 3A - For Airplane Models with a Dedicated Zonal Inspection Program (ZIP) 05/04/10 Enhanced Zonal Analysis - Inspection Level Determination Based on Zone Size, Density, and Potential Impact of Fire (step 8 of figure 1, refer to figure 2) Zone Number: Zone Description:
Density / Zone Size —→ Zone Size Inspection Level Determination Based on Potential Effect of Fire in the Zone
• Assessment Small Medium Large Size / Density Factor 1 2 3 Low 1 2 3 Low Zonal GVI Zonal GVI Zonal GVI Density Medium 2 2 3 Potential Zonal GVI + Zonal GVI + Effects of Fire Medium Zonal GVI stand-alone GVI of stand-alone GVI of in the Zone some EWIS some EWIS High 2 3 Zonal GVI + Zonal GVI + Zonal GVI + High stand-alone GVI of stand-alone GVI and/or stand-alone GVI and/or some EWIS DET of some EWIS DET of some EWIS Circle appropriate result & insert below Circle appropriate result and answer questions in the boxes below RESULT YES Answers and Explanations
1. Is a Zonal GVI alone 2. List zone effective for the entire description and zone?* boundaries for Zonal - The tables on this worksheet are used to select the appropriate level of inspection for the EWIS in the zone GVI based on an assessment of zone size, density, and potential effects of fire in the zone.
This worksheet assumes the existing maintenance program already includes a dedicated zonal inspection program. It is assumed that an existing ZIP already includes a zonal GVT of all zones that contain wiring Define specific and other EWIS components, and that the inspection of the EWIS is included in the zonal GVI.
items/areas in the 2 Zonal GVI must be zone for which a If existing zonal GVI is an effective inspection task for all of the EWIS in the zone, the analysis must be augmented with a Stand-alone GVI is continued to determine the appropriate inspection interval (worksheet 4). During task consolidation afler stand-alone GVI justified completion of the analysis, the most frequent zonal GVI interval for the zone will take precedent.
and/or a DET inspection If the results of the analysis contained on worksheet 4 indicate that the EWIS inspection interval is greater than the interval for the existing zonal GVI, the existing zonal GVI interval cannot be escalated based
• If answer to box 1 is "YES," answer box 2 only and 4. Define specific solely on the results of the EZAP analysis.
then continue the analysis on worksheet 4 in order → zone for which a DET items/areas in the If a zonal GVI is not adequate for the EWIS in the zone, in addition to identifying the zonal GVI, the Appendix A AC 25-27A to determine the task interval. s justified 4 analyst must also identify the specific items/areas in the zone where a stand-alone GVI and'or DET inspection is necessary.
If answer to box 1 is "NO." answer boxes 2, 3, and 4 and then continue the analysis on worksheet 4 in order to determine the task interval.
EZAP WORKSHEET 3B - For Programs without a Dedicated Zonal Inspection Program (ZIP) 05/04/10 Enhanced Zonal Analysis - Inspection Level Determination Based on Zone Size, Density, and Potential Impact of Fire (step 8 of figure 1, refer to figure 2) Zone Number: Zone Description:
Density / Zone Size -• Zone Size Inspection Level Determination Based on Potential Effect of Fire in the Zone
• Assessment Small Medium Large • Size / Density Factor 2 Low 1 2 GVI of all EWIS in zone at GVI of all EWIS in zone at GVI of all EWIS in zone at Low same interval same interval same interval Density Medium 2 2 Effects of Potential Medium GVI of all EWIS in zone at same interval same interval + GVI of some GVI of all EWIS in zone at EWIS at more frequent GVI of all EWIS in zone at same interval + GVI of some EWIS at more Fire in the Zone interval frequent interval High 3 GVI of all EWIS in zone at GVI of all EWIS in zone at GVI of all EWIS in zone at same interval + GVI of some same interval + GVI of some High same interval + GV of some EWIS at more EWIS at more frequent EWIS at more frequent Circle appropriate result & insert below frequent interval interval and/or DET of some EWIS interval and/or DET of some EWIS RESULT Circle appropriate result and answer questions in the boxes below YES Answers and Explanations
1. Is a GVI alone 2. List zone effective for all EWIS in description and interval?* the zone at the same NO boundaries for GVI of all EWIS in the zone The tables on this sheet are used to select an inspection level based on zone size, density, and potential effect of fire in the zone. These factors are used to determine if a GVI of all EWIS in the zone at the same interval is adequate, or if some EWIS requires a more frequent GVI, or even a DET.
3. Define specific items/areas in the This worksheet is designed for operators whose existing maintenance zone for which GVI at program does not include a dedicated zonal inspection program. The Some EWIS requires more frequent minimum outcome of this analysis will always be a GVI of all EWIS in any GVI at more frequent interval is justified zone where the presence of combustible materials is possible and/or interval and/or DET wiring is located in close proximity to both primary and backup hydraulic or mechanical flight controls.
inspection
4. Define specific If a GVI of all EWIS in the zone at the same interval is adequate, the * If answer to box 1 is "YES," answer box 2 only and then continue the analysis on worksheet 4 in order to items/areas in the zone for which a DET analyst must identify the inspection requirement as "GVI of all EWIS in the zone" (box 2) and proceed to worksheet 4 to determine the GVI interval. Appendix A AC 25-27A determine the task interval. is justified If a GV of all EWIS in the zone at the same interval is not adequate, then If answer to box 1 is "NO." answer boxes 2, 3, and 4, the analyst must identify the specific items/areas in the zone where a and then continue the analysis on worksheet 4 in order to more frequent GVI (box 3) and/or a DET (box 4) is justified.
determine the task interval.
EZAP WORKSHEET 4 - Intervals Based on "A" and "C" Checks 05/04/10 Enhanced Zonal Analysis - Interval Determination Based on Hostility of Environment and Likelihood of Accidental Damage (step 8 of figure 1, refer to figure 2) Zone Number: Zone Description:
Likelihood of Accidental Damage Hostility of Environment Enter Number Here L 1 - Passive / 2 - Moderate / 3 - Severe Enter Number Here 1 - Passive / 2 - Moderate / 3 - Severe Ground handling equipment Temperature Foreign object debris (FOD) Vibration Weather effects (hail, rain, etc.)
Chemicals (toilet fluids, de-icing fluid, etc.)
Frequency of maintenance activities Humidity Fluid spillage Contamination Passenger Traffic Other Other Enter the Highest Number Here Enter the Highest Number Here Likelihood of Accidental Damage Interval Determination Interval selection is specific to each task identified on 2 3 worksheet 3A or 3B. For GV of entire zone, consider overall 1 14, 400 - 21,600 60 - 90 M 4C - 6C FH 7,200 - 14,400 FH 30 - 60 M 2C - 4C 3,600 - 7,200 FH 15 - 30 M 1C - 2C zone environment and likelihood of damage. For stand-alone GVI or DET, consider environment and likelihood of damage inspection. only in respect to the specific item/area defined for Examples of task interval ranges NOTE: Interval ranges are quoted in the rating table to 2C - 6C 1C - 4C A - 1C Hostility of 2 7,200 - 21,600 FH 3.600 - 14,400 FH 450 - 3,600 FH explain a typical arrangement of values. For a particular Environment 30 - 90 M 15 - 60 M 1 - 15 M application, these must be compatible with the interval framework used in the existing maintenance or inspection program (as detailed in the current MRBR). They may be 1C - 6C 1C - 4C A - 1C expressed in terms of usage parameter (for example, flight 3 3.600 - 21.600 FH 3,600 - 14,400 FH 450 - 3.600 FH hours or calendar time) or in terms of letter check.
15 - 90 M 15 - 60 M 1 - 15 M The inspection frequency should be based on increasing risk Appendix A AC 25-27A RESULT of accidental damage and increasing severity of the local Upon completion, enter all task and interval selections onto environment within the zone. In other words, the more worksheet 5, Task Summary ratings identified as moderate and severe should drive the inspection towards the lower end of the interval.
Enhanced Zonal Analysis - Task Summary EZAP WORKSHEET 5 05/04/10 Zone Number: Zone Description:
TASK SUMMARY Task Number Access Task Interval Task Description and Applicable Comments/Rationale/Assumptions Appendix A AC 25-27A
Appendix B
Appendix B
1. Evaluating Whether a Design Change Impacts Previously Approved EWIS ICA and Developing any Necessary New or Revised ICA as Required by § 26.11(c) or § 25.1729.
a. Section 26.11(c) requires that applicants for amendments to type certificates (TCs), supplemental type certificates (STCs), and changes to STCs evaluate whether the design changes for which approval is sought require revisions to previously approved EWIS ICA.
b. Section 26.11(c) applies to all design changes (provided the design change is related to an affected airplane model as determined by § 26.11(a)), not just those that include EWIS modifications. For example, if an applicant proposes to modify stow bin latches, it should be relatively easy for the applicant to make a statement that the EWIS ICA are not impacted. On the other hand, if an applicant introduces a new hydraulic line, or creates a hole in a zone that previously did not have one, some of the previously developed EWIS ICA may be impacted. For example, the modification may introduce new sources of contamination that were not previously addressed by the EWIS ICA.
c. This appendix provides guidance to help the applicant determine whether the proposed modification impacts previously approved EWIS ICA. It also provides guidance to help applicants meet the compliance plan requirements of § 26.11(e) if no EWIS ICA additions or revisions are necessary. Section 26.11(e) requires applicants for amended TCs, STCs, and changes to existing STCs to submit a compliance plan to the FAA for approval if the date of application for the modification was prior to the effective date of § 26.11 and the certificate was issued on or after the effective date. If following the logic in flowchart 1 results in a determination that the previously approved EWIS ICA must be revised because of the modification, guidance for developing and submitting a compliance plan to the FAA oversight office may be found in AC 26-1, Part 26, Continued Airworthiness and Safety Improvements.
Note: Each person (applicant) identified in § 26.11(d)(1), (d)2), and (d)(4) must comply with the requirements of § 26.11(e) no matter what the nature of the modification for which they are seeking approval—even if the modification does not require a revision to previously approved EWIS ICA.
d. You can determine whether an amended TC, STC, or changes to an existing STC (referred to in this appendix as a “modification”) requires revision to previously approved EWIS ICA by following the process outlined in flowchart 1 of this appendix.
e. When using flowchart 1 of this appendix, you should refer to the guidance in the body of the AC, and appendix A for additional help, in understanding the questions being asked and the assumptions you should make while following the various logic steps of flowchart 1.
f. This appendix should also be used for design change proposals for which § 25.1729 is included in the certification basis.
B-1
Appendix B Flowchart 1 Development of EWIS ICA for Design Changes 1 Does the design change:
• Install new, or modify existing, EWIS in the zone(s)? -OR
• Install, or modify existing, wire or other EWIS components, that will result in those components being located within 2 in / 50mm of BOTH primary AND backup hydraulic, mechanical, or electrical flight controls? -OR-
• Increase the density of zone? (for example, by adding a new airplane system or -NO adding components to an existing system) -OR-
• Introduce the possibility of new contaminants or combustibles in the zone? (for example, by adding or revising hydraulic or fuel components, by a structural modification) -OR- No further analysis is required
• Install, or modify, existing, EWIS or other systems that would increase the negative potential effects if a fire were to occur in the zone?
YES Are you the holder of the airplane models type certificate, or do you have access to the most recent EZAP analysis performed on the zone(s) you are modifying, or all design and installation data that is necessary to answer all the questions that are asked while performing the EZAP analysis as described in appendix A of this YES AC? NO Go to page 2 of this Go to page 3 of this flowchart flowchart Submit a statement to the FAA oversight office, ACO, or office of the Transport Airplane Directorate, as applicable, stating there is no impact to previously approved EWIS ICA and provide a detailed rationale of the reasons that this conclusion was reached. The following statement can be used for this purpose:
"The modification has been reviewed per the guidance provided in FAA AC 25-27. It has been determined that the modification does not necessitate a revision to the EWIS ICA that were required to be developed by § 26.11(b) / § 25.1729* 1: A design change means any change to an existing type design accomplished through any of the following:
- Amended type certificate, including service bulletin design changes, (Sic) lemental type cerificate
- Changes to an existing STC B-2
Appendix B Flowchart 1, Page 2 From Flowchart, Page 1, Step 4 Perform an EZAP on the zone(s) you are modifying per the guidance contained in Are there existing EWIS ICA Appendix A of this AC. After doing this (i.e., FAA approved EWIS ICA -NO you can then determine if any existing prior to your modification) for EWIS ICA are adequate, need revising, or the zone(s) that were modified?
if new ICA are necessary YES Submit any EWIS ICA Since there are existing Since you have access to developed in Step 6 to the EWIS ICA for the zone(s) you the most recent EZAP for FAA Oversight Office for must now determine if these the zone(s) or to the review and approval. If the existing ICA are adequate for necessary design and EZAP did not identify any the modified zone(s), if they installation data you can necessary maintenance and need to be revised, or if easily make this inspection tasks, then submit a additional ICA are necessary determination statement to the FAA Oversight Office stating this Since you answered YES to 11 one or more of the questions in Will the existing EWIS ICA The existing EWIS ICA are not adequate for the modified zones Step 1 (i.e., you added or result in the complete You must submit new or revised EWIS ICA for the zone(s) being modified EWIS, non-EWIS inspection of all EWIS modified to the FAA Oversight Office for review and approval.
modifications, or a combination components, made structural design change, or clean the added or modified by the NO These new or revised EWIS ICA must be based on the results of an EZAP performed per the guidance contained in Appendix A of these to the zone(s), answer zone of any contaminants of this AC? Remember the EWIS ICA submitted to the FAA the following questions: or combustibles added by must comply with the identification and documentation the design change? requirements of part 25, appendix B, section H25.5(b).
Revise existing EWIS ICA or create new EWIS ICA as necessary based on the design change's impact on the various rating tables Did the addition/modification of and access requirements and assigned ratings contained in the these items cause the previously Submit them EWIS ICA to the FAA Oversight Office for review and approval. Remember the EWIS ICA submitted to the FAA must size/density table, or potential comply with the identification and documentation requirements of effects of fire table to increase in part 25, appendix B, section H25.5(b).
value (e.g., from a 2 to 3 or low to medium)?
-YES Did the addition/modification of these items cause an increase in YES the values assigned previously in 'ES the Hostility of Environment of Likelihood of Accidental Damage ratings?
Did the addition/modification of these items cause an increase NO in the values assigned previously in the Hostility of Environment of Likelihood of 2: Ensure that any new or Accidental Damage ratings?
revised EWIS ICA remain compatible with ICA developed to comply with SFAR 88 and Did the modification alter the that any redundant requirements access requirements for the between the EWIS and SFAR existing EWIS ICA? In other 88 ICA are minimized (as The existing EWIS ICA can be considered as words, can the existing ICA required by 26.11(c)(2). Refer adequate and no further analysis is necessary. be accomplished using the to paragraph 2.c(2) in the main Submit a statement to the FAA Oversight access requirements body of this AC for more Office or ACO, as applicable stating there is associated with the existing information on this requirement. no impact to previously approved EWIS ICA task?
B-3