AC 120-102B

Advisory circular · Incorporation of Electrical Wiring Interconnection Systems Instructions for Continued Airworthiness into an Operator's Maintenance Program

Approved
June 3, 2024
Last reviewed
June 3, 2024
This change
Applicable to SFAR 88.
Family
AC 120-102 · 5 versions
Revision
B
14 CFR parts
21, 25, 26, 43, 121, 129

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

Show pages 1–12

2-4 the applicable part 26 provision. Section 21.101 is referred to as the “Changed Product Rule.” The EWIS ICA required by § 25.1729 are developed under §§ H25.4 and H25.5.

Simply stated, an operator can have airplanes that have the EWIS ICA developed under § 26.11 or, if applicable, EWIS ICA developed under § 25.1729, which includes § H25.5 and any mandatory replacement times for EWIS components.

2.4 DAH Activities for Compliance with § 26.11. The DAH is required to develop ICA for the “representative airplane’s” EWIS according to § 26.11, as follows:

2.4.1 TCH. The TCH is required to develop the EWIS ICA for the “representative airplane” in accordance with § 26.11(b). The purpose was to ensure that all variations of the EWIS used in production were reviewed and appropriate ICA were developed. These EWIS ICA were developed in accordance with § H25.5(a)(1) and (b) in effect on December 10, 2007, for each affected type design. The TCH submits those ICA for review and approval by the responsible Aircraft Certification Service office.

Note: TCHs with § 25.1729 i n their certification basis will develop the EWIS ICA in accordance with §§ H25.4 and H25.5.

2.4.2 TC/STC Holders. T C/STC holders are only required to develop the EWIS ICA in compliance with § 26.11(c) or, if required or elected, in compliance with part 25 appendix H, § 25.1729 if the application date for the STC or change to an existing TC/STC was before December 10, 2007, and the FAA issued the certificate on or after December 10, 2007. Applicants for STCs (including changes to existing STCs) or amended TC holders applications filed on or after December 10, 2007, are also required to develop and submit EWIS ICA in compliance with § 26.11 or, if required or elected, in compliance with § 25.1729 for review and approval to the responsible Aircraft Certification Service office.

Note: Amended TC/S TC holders with § 25.1729 in their certification basis will develop the EWIS ICA in accordance with §§ H25.4 and H25.5.

2.5 Why the EWIS ICA Approval is Necessary. While there may be DAH or operator created ICA that appear to be acceptable, before they are applied, the responsible Aircraft Certification Service office must review and approve the EWIS ICA. The development of the EWIS ICA requirements can be complex, requiring qualitative engineering and maintenance assumptions. Approval will help ensure standardized application of these assumptions (e.g., zone density, zone size, potential effects of fire, environmental effects, etc.) and ensure that important information such as wire identification requirements and EWIS separation requirements developed during airplane certification are correctly and logically documented in the airplane’s ICA documents. It will also ensure that the data/documents delivered to the operators will be standardized to the extent required by the EWIS ICA requirements.

2.6 TCH-Developed EWIS Recommended Maintenance Requirements. EWIS ICA are developed in accordance with §§ H25.4 and H25.5. The responsible Aircraft Certification Service office approves all of these EWIS ICA. The TCH can develop the EWIS ICA in

2-5 accordance with § 26.11(b) or (c) by showing compliance with § H25.5(a)(1) and (b); or in accordance with § 25.1729 by showing compliance with §§ H25.4 and H25.5; or by utilizing an existing document for scheduled tasks and the intervals for performing those tasks and procedures, the Maintenance Steering Group – 3rd Task Force (MSG-3) logic contained in the Airlines for America (A4A) Operator/Manufacturer Scheduled Maintenance Development Document (MSG-3), or any other acceptable method of compliance with §§ H25.4 and H25.5 and AC 25-27. The EWIS ICA will be identified as the EWIS ICA as required by § H25.5(b) in the source document developed by the TCH.

As stated earlier in this AC, the TCH should:

1. Develop a source document that contains all of the EWIS ICA data required by § H25.5(a)(1);

2. Develop a source document that references other maintenance documentation that contains the EWIS ICA data required by § H25.5(a)(1); or

3. Utilize an existing document (such as the MRBR, MPD, or MID) to provide the data or the references specified in items 1 and 2 above, respectively.

Note: With reference to TCH Service Bulletins (SB) that affect the EWIS, the FAA expects that the TCH will identify protections and caution information in a manner or form that conveys the information to the operator. For example, one TCH states in every SB that affects the EWIS this cautionary statement: keep the work area, wires, and electrical bundles clean of metal particles or contamination when you use tools. Unwanted material, metal particles, or contamination caught in wire bundles can cause damage to the bundles. Damaged wire bundles can cause sparks or other electrical damage.

2.6.1 Overview. The EWIS ICA developed from application of the en hanced zonal analysis procedure (EZAP) should be located in the systems and powerplant section under Air Transport Association of America (ATA) 20, and the zonal inspection program section of the airplane’s MRBR, MPD, MID, or a source document. They consist of recommended maintenance tasks, task intervals, and instructions/procedures to accomplish the tasks.

With respect to inspection tasks, the inspection can be a zonal GVI, standalone GVI, DET, or a combination of these. The TCH selects task intervals that are adequate to maintain the airplane airworthiness in order to provide operators with a means to properly maintain the EWIS, while still allowing flexibility for the operators to schedule maintenance tasks within their maintenance programs.

2.6.2 Location.

2.6.2.1 All of the EWIS ICA for which compliance is recommended will be in the source document, or the source document will reference other document locations.

2.6.2.2 Operators must incorporate into their maintenance program EWIS ICA that have been approved by the responsible Aircraft Certification Service office.

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2.6.3 Instructions and Procedures.

2.6.3.1 The instructions/procedures to carry out the EWIS tasks will be contained in the AMM, SWPM, and ESPM.

2.6.3.2 Operators should incorporate instructions/procedures that have been approved in their maintenance program/manuals, work cards, job/task cards, Engineering Authorizations/Engineering Orders (EA/EO), etc. It is especially important that the task descriptions, job accomplishment instructions, task cards, job/task cards, etc. contain all the instructions and procedures that support the EWIS task.

2.6.4 Protections and Caution Instructions and Information. The EWIS ICA also includes protections and caution instructions and information that will minimize contamination and accidental damage to the EWIS during the performance of maintenance, alterations, or repairs. Inspections of other airplanes after the Boeing 747 and MD-11 accidents showed that contamination of wire bundles with metal shavings, dust, and fluids were common conditions in representative examples of the aging fleet of transport airplanes.

These contaminants could damage the EWIS and also provide fuel for an electrical fire.

The TCH has developed these protections and caution instructions and information to support the EWIS maintenance program for the airplane. These protections and caution instructions and information will be in the AMM, SWPM and ESPM. Only those sections affected by the incorporated protections and caution instructions and information to support the EWIS are approved, not the entire manual.

2.7 STC Holder-Developed EWIS ICA. Section 26.11 applies to applicants for STCs (including changes to existing STCs) if the date of application was before December 10, 2007, and the STC was issued on or after that date. Unless compliance with § 25.1729 is required or elected, the rule also applies to applications for STCs (including changes to existing STCs) filed on or after December 10, 2007.

2.8 STC Limitation. Part 26 does not prohibit issuing an STC even if the STC applicant has not yet met the requirements of that section. In this case, the FAA will add a limitation to the STC. FAA engineering policy memo PS-AIR-100-2007-12-27B, Enhanced Airworthiness Program for Airplane Systems (EAPAS) Supplemental Type Certificate (STC) Limitation, dated June 10, 2009, describes how and when the FAA will do this. You can download an electronic copy at https://drs.faa.gov.

2.8.1 Limitation Statement. It is important for the operator to understand that this is a limitation on the STC applicant and not the operator. The following statement (as described in PS-AIR-100-2007-12-27B) should be added to the Limitation Section of the STC when the EWIS ICA evaluation has not been completed at the time of the STC issuance (provided it is issued prior to June 7, 2010). The goal of the limitation is (1) to not allow any installations after August 30, 2010, if an STC applicant has not met the § 26.11 EWIS requirements; and (2) to not ground any airplanes that already have the STC installed.

2-7 “This modification may not be installed after August 30, 2010 unless (1) previously approved electrical wiring interconnection system (EWIS) instructions for continued airworthiness (ICA) have been evaluated and determined to be adequate for this installation by the FAA, or (2) revised EWIS ICA have been approved by the responsible Aircraft Certification Service office. (Refer to § 26.11.)”

2.8.2 I nstallation After August 30, 2010. In order for the operator to install the STC after August 30, 2010, the operator will need to have one of the following:

1. A letter from the responsible Aircraft Certification Service office stating that the previously approved EWIS ICA have been evaluated and shown to be adequate for the modification. The operator should request this letter from the responsible Aircraft Certification Service office to ensure that the STC has been evaluated in accordance with § 26.11(c)(1) and (2) prior to installation; or

2. Revised EWIS ICA that the responsible Aircraft Certification Service office has approved for the STC modification. The revised EWIS ICA should be provided to the operator by the STC holder.

Note: Once the STC holder has met the § 26.11 requirements, the STC does not need to be revised to remove the statement. However, if the STC needs to be updated/amended, the limitation may be removed at that time.

2.8.3 E xisting STCs After August 30, 2010. As stated above, this is a limitation on the STC applicant, not on the operator. Operators can continue to operate their airplanes with the existing STC after August 30, 2010. The operator has no obligation under the operation rules (§§ 121.1111 and 129.111) to develop the EWIS ICA for the existing STC. If the STC holder provides the EWIS ICA that have been approved by the responsible Aircraft Certification Service office for the previously incorporated STC (STC installed after the effective date of the rule), the operator should assess them for incorporation into its maintenance program.

Note: If a n STC limitation remains, no person may approve for return to service an airplane modified in accordance with the installation instructions of the STC after August 30, 2010, even if an operator operates airplanes that had the design change installed on the same airplane model prior to August 30, 2010.

2.9 Requirement to Ensure Compatibility Between Fuel Tank System and EWIS ICA.

Section 26.11 requires a review by the TC and STC holders of any fuel tank system ICA developed to comply with Special Federal Aviation Regulation (SFAR) 88, Fuel Tank System Fault Tolerance Evaluation Requirements. This ensures compatibility with the EWIS ICA and minimizes duplication of requirements between them. Fuel tank wiring is part of the aircraft’s EWIS. The fuel tank system maintenance requirements might be more specific than those for wiring in general and might contain additional requirements.

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2.9.1 TC and STC Holder Review. The DAH will review ICA to ensure that any maintenance tasks for the EWIS do not compromise fuel tank system wire requirements, such as separation or configuration specifications. Operators need to be aware that separation and configuration of the EWIS, especially when performing a repair or alteration to the EWIS or fuel tank system wiring, may be critical.

Note: The responsible Aircraft Certification Service office must approve any ope rator-proposed changes to separation and configuration of the EWIS or fuel tank system wiring. The operator must submit its proposed changes with supporting technical justification/data through the principal inspector (PI). The PI adds comments (if any) and forwards the proposed changes to the responsible Aircraft Certification Service office for approval.

2.9.2 Fuel Tank System and EWIS ICA Location. The responsible Aircraft Certification Service office approves the TC and STC ICA for EWIS. With respect to the recommended repetitive maintenance instructions, the TCH will typically list the EWIS and fuel tank system tasks and intervals in its manual or section of ICA for the airplane that is required to comply with § H25.3(b)(1). They are identified as the EWIS ICA or the EWIS/SFAR 88 ICA. The STC holder will typically list its ICA in the STC document it provides.

2.9.3 Example. T he following table is an example of how a TCH has identified an integrated EWIS/SFAR 88 task within its manual or section of ICA for the airplane that is required to comply with § H25.3(b)(1). STC holders may identify them differently and include them in the ICA section of their documents. Each task is identified as an EWIS task or SFAR 88 task. An integrated task will be identified as an EWIS/SFAR 88 task. Operators should identify the EWIS tasks and the integrated EWIS/SFAR 88 tasks in their maintenance program so as not to lose their identity as part of an approved ICA.

1. Column 1 identifies the task number, in this case 20-XXX. The task number 20-XXX is only an example for illustration purposes in this AC. An actual TCH task number will probably contain six or more numbers, such as 20-XXX-XX. Some may also be in ATA 28, so the task may be 28-XX-XX.

2. Column 2 is the task category, which is a DET.

3. Column 3 is the task interval, 6C.

4. Column 4 is airplane applicability.

5. Column 5 is a description of the task and, in this case, is an integrated EWIS/SFAR 88 task.

2-9 Table 2-1. Integrated Enhanced Airworthiness Program for Airplane Systems/Fuel Tank Safety Task

1. It em 2. Task Category 3. Task Interval 4. Airplane Applicability 5. Task Description 20-XXX * DET 6C All Inspect exposed EWIS/FQIS, etc. EWIS/SFAR 88 *Subparagraph 2.9.3

2.10 Operator-Developed EWIS ICA. The FAA recognizes that some operators may want to and can develop (using AC 25-27) their own EWIS ICA compliant with § H25.5(a)(1) and (b) (e.g., when their maintenance programs have not been developed using MSG-3).

Operators can incorporate into their maintenance programs the TC or STC holder’s EWIS ICA, or their own ICA (as a complement or an alternative) once these EWIS ICA are approved by the responsible Aircraft Certification Service office.

Note: Important information for the operator: If the operator develops its own EWIS ICA, the responsible Aircraft Certification Service office must approve them. The operator must forward its proposed EWIS ICA through the PI. The PI adds comments (if any) and forwards the proposed EWIS ICA to the responsible Aircraft Certification Service office for approval. Operators must incorporate into their maintenance program EWIS ICA that have been approved by the responsible Aircraft Certification Service office.

3-1 CHAPTER 3. OPERATIONAL REQUIREMENTS

3.1 Operator Incorporation of Federal Aviation Administration (FAA)-Approved Electrical Wiring Interconnection System (EWIS) Instructions for Continued Airworthiness (ICA) into the Maintenance Program. Title 14 of the Code of Federal Regulations (14 CFR) part 121, § 121.1111 and part 129, § 129.111 require operators to incorporate into their maintenance program inspections and procedures for EWIS contained in ICA approved by the responsible Aircraft Certification Service office. The FAA expects that type certificate holders (TCH) will incorporate the approved EWIS ICA into their Maintenance Review Board Report (MRBR) or Maintenance Implementation Document (MID) and make them available to operators either electronically or in hard copy. The FAA expects that Supplemental Type Certificate (STC) holders will make them available by similar means. (Refer to Advisory Circular (AC) 20-188, Compatibility of Changes to Type Design Installed on Aircraft.)

3.1.1 Operator’s Tracking System. The operator should establish a tracking system within its maintenance program that tracks the incorporation of, and any revisions to, the responsible Aircraft Certification Service office-approved EWIS ICA, so the ICA will not lose their identity as an FAA-approved EWIS ICA. This includes:

1. Task and intervals;

2. Instructions and procedures in the Aircraft Maintenance Manual (AMM), Standard Wiring Practice Manual (SWPM), and Electrical Standard Practices Manual (ESPM);

and

3. Protections and caution instructions and information in the AMM, SWPM, and ESPM.

3.1.2 Controlling Reference Numbers. TCHs’ controlling reference numbers uniquely identify the EWIS ICA for identification and traceability purposes throughout the operational life of the airplane. During the initial incorporation of the EWIS ICA into the operator’s maintenance program, the operator should use these controlling reference numbers or an operator-developed system that correlates to them for the purposes of traceability. This will provide operator traceability during future maintenance program changes that contain EWIS ICA. This will help prevent inadvertent deletion, changes to the type of task, or escalation of EWIS ICA without proper consideration of the reason for the task and its interval. The tracking system should correlate to the controlling reference number for the EWIS ICA and be acceptable to the principal inspector (PI).

3.1.3 P rotections and Caution Instructions and Information in the Maintenance Program/Manual. It is important that the operator incorporate protections and caution instructions and information into its maintenance program/manual to minimize contamination and accidental damage to the EWIS when performing maintenance, alteration, or repairs. In addition, the operator should have procedures in its maintenance program/manual that instruct its maintenance personnel “to clean the EWIS and surrounding area after completion of any maintenance, alterations, or repairs.” It is especially important to include the same or a similarly worded statement in their

3-2 program/manuals, work cards, job/task cards, Engineering Authorizations/Engineering Orders (EA/EO), etc.

3.1.4 O perator-Developed Instructions and Procedures for EWIS Tasks. The operator can develop its own instructions and procedures to carry out the EWIS tasks provided the operator-developed ones produce an equivalent result to those approved by the responsible Aircraft Certification Service office. If the AMM, SWPM, and ESPM allow for the use of alternative or equivalent tools or materials, further approval by the responsible Aircraft Certification Service office is not required. If the operator proposes to change the instructions, procedures must be submitted and found acceptable by the PI.

The operator should include supporting technical justification and data with its submittal.

PIs should contact the responsible Aircraft Certification Service office for concurrence.

3.1.5 Ensuring Th at Protections and Caution Instructions and Information are in Operator Documents. The operator is responsible for ensuring that protections and caution instructions and information approved by the responsible Aircraft Certification Service office are incorporated into its maintenance program manuals, work cards, job/task cards, EA/EOs, etc., and any other documents the operator uses in administering their maintenance program. The operator should have procedures in its maintenance program manuals that instructs personnel who write or revise manuals, work cards, job/task cards, EA/EOs, etc., that all protections and caution instructions and information must be incorporated in those documents as appropriate. It is especially important to include and clearly identify the protections and caution instructions and information on work cards, job/task cards, and EA/EOs.

3.1.6 Operator-Developed Docume nts That Include EWIS Inspection Tasks.

Operator-developed work cards, job/task cards, EA/EOs, etc., that include any EWIS inspection tasks should have the protections and caution instructions and information included, and should reference the location in the AMM, SWPM, or ESPM.

3.2 O perator Changes to Enhanced Zonal Analysis Procedure ( EZAP)-Developed EWIS Task or Task Intervals.

3.2.1 T ypes of Changes . There are two types of changes to the operator’s EWIS maintenance program:

• D eletion of or changes to an EWIS task, or

• Escalation of an airplane check package/interval, such as “C check” containing the EWIS tasks and intervals.

3.2.2 R esponsible Aircraft Certification Service Office Approval. If the operator proposes to delete or change an EWIS task, it must be approved by the responsible Aircraft Certification Service office. The operator should submit its proposed changes with supporting technical justification/data through the PI. The PI adds comments (if any) and forwards the proposed changes to the responsible Aircraft Certification Service office for approval.

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3.2.3 Escalation of an Airplane Check Package/Interval. If the operator proposes an escalation of an airplane check package/interval, such as the “C check” that contains EWIS tasks and intervals, the responsible Aircraft Certification Service office does not have to approve the change. This change is within the authority of the PI and the procedures in the operator’s maintenance program and manuals. The operator should provide the PI with technical justification for escalating any EWIS tasks and intervals.

3.3 Operator Changes to EWIS ICA Developed Under 14 CFR Part 25, § 25.1729.

3.3.1 Requirements. EWIS ICA compliant with part 25 appendix H, §§ H25.4 and H25.5 are required if the airplane has § 25.1729 in its certification basis, or if the responsible Aircraft Certification Service office has determined that an STC applicant must comply with 14 CFR part 21, § 21.101 and, therefore, require the applicant to comply with all or parts of the EWIS requirements of § 25.1729.

3.3.2 A pproval. Operators should discuss any proposed changes to the EWIS requirements with the PI and the responsible Aircraft Certification Service office to see if the proposed changes are within the authority of the PI and the procedures within the operator’s maintenance program, or if they must be approved by the responsible Aircraft Certification Service office.

3.4 EAPAS Maintenance Training. The Enhanced Airworthiness Program for Airplane Systems/Fuel Tank Safety (EAPAS/FTS) Rule introduced new requirements that affect design approval holders (DAH) and operators. To realize fully the objectives of EAPAS/FTS requirements, the FAA encourages operators to rethink their current philosophical approach to maintaining, inspecting, and altering aircraft wiring and systems in the aircraft. The FAA has also adopted the “Protect and Clean as You Go” philosophy. This philosophy stresses:

3.4.1 Protective Measures. The importance of protective measures when working on or around wire bundles and connectors.

3.4.2 D ebris Removal . The importance of protecting the EWIS during structural repairs, STC installations, or other alterations by making sure that metal shavings, debris, and contamination resulting from such work are removed during work in progress and after completion.

3.4.3 O perator Training . This philosophical approach begins at the airplane manufacturer with enhancements of ICA for scheduled maintenance, changes to ICA maintenance procedures, and maintenance training programs. Operators will need to educate and train their employees of addition and identification in their AMM, SWPM, ESPM, work cards, job/task cards, EA/EOs, etc., that include any EWIS inspection tasks, protections and caution instructions and information. In addition, there will be new procedures, inspection devices, graphical information showing required tasks, changes in tasks such as wiring splicing, etc. Operators should provide training to maintenance, inspection, and engineering personnel, including persons who write and edit job cards and engineering orders. The FAA has published AC 120-94, Aircraft Electrical Wiring Interconnection

3-4 Systems Training Program, to assist operators in development of the EWIS training programs.

3.4.4 Manufacturer-D eveloped Training Programs. Operators can also take advantage of any airplane manufacturer-developed training programs that address the EWIS.

3.5 Operator’s Maintenance Program Approval Under §§ 121.1111 and 129.111.

Operators of transport category airplanes to which §§ 121.1111 and 129.111 apply must incorporate the EWIS ICA into their maintenance programs inspections and procedures for EWIS on the basis of ICA developed in accordance with the provisions of § H25.5(a)(1) and (b), or § H25.4 and all of § H25.5, as applicable. Sections 121.1111(e) and 129.111(e) state that these changes to the maintenance program and any later revisions to the EWIS provisions of the maintenance program must be submitted to the PI for review and approval. The operator will submit to the PI for review the revisions to their maintenance program incorporating inspections and procedures for EWIS, and their revisions. The PI will ensure the operator has incorporated into their maintenance programs inspections and procedures based on EWIS ICA and any subsequent revisions that have been approved by the responsible Aircraft Certification Service office. When the review is complete, the PI will issue or amend Operations Specification (OpSpec)/Management Specification (MSpec) D097, Aging Aircraft Programs.

3.6 Operations That are Authorized OpSpec D097. The issuance of this OpSpec signifies the FAA has reviewed the operator’s, certificate holder’s (CH), or program manager’s policy and procedures incorporated into their maintenance programs for compliance with the Aging Aircraft Program rules. Table 1 of D097 will consist of three columns that list:

• The applicable Aging Aircraft Program rules;

• The manual and section where the policy and procedures are located for the applicable Aging Aircraft Program; and

• The date of the manual and section where the current policy and procedures are located for the applicable Aging Aircraft Program.

Note 1: Table 3-1 below illustrates a sample D097 Table 1 that lists the various 14 CFR part rules. The operator/CH/program manager will have a specific OpSpec D097 template for their operation.

Note 2: If the rule does not apply to the CH’s operation, list the associated rule f or their operation (e.g., § 121.1113) in the first column and enter “N/A” in the second and third columns.

3-5 Table 3-1. Sample D097 Table 1 – Aging Aircraft Maintenance Programs Aging Aircraft Program Rules Certificate Holder/Program Manager’s Maintenance and Inspection Program Policy and Procedures (Manual and Section) Date Repairs Assessment for Pressurized Fuselages — § 121.1107, § 129.107

Supplemental Inspections — § 121.1109, § 129.109

Electrical Wiring Interconnection Systems (EWIS) Maintenance Program — § 121.1111, § 129.111

Fuel Tank System Maintenance Program — § 121.1113, § 129.113

Flammability Reduction Means — § 121.1117, § 129.117

3.6.1 Submission to PI for Review.

3.6.1.1 Initial submission and any subsequent revisions to these policy and procedures sections must be submitted to the PI for review for compliance with the Aging Aircraft Program rules.

3.6.1.2 Any changes to the operator/CH/program manager’s maintenance program policy and procedures must be submitted to the PI for review and approval.

When the maintenance program policy and procedures are revised, the date of the revision will be inserted into column 3 of Table 3-1.

3.6.2 FAA Aircraft Certification Service Office-Approved ICAs. Any proposed revisions or deletions of responsible Aircraft Certification Service office-approved ICAs must be coordinated with the PI for review and concurrence. The PI will then forward the proposed revisions or deletions to the responsible Aircraft Certification Service office for approval prior to implementation or incorporation into the maintenance program.

3.6.3 O perator Action. An operator/foreign air carrier/foreign operator must have procedures to ensure that EWIS ICAs for inspections and procedures are incorporated into their maintenance program.

Appendix A A-1 APPENDIX A. ACRONYMS 14 CFR Title 14 of the Code of Federal Regulations A4A Airlines for America AC Advisory Circular AD Airworthiness Directive AED Aircraft Evaluation Division AIR Aircraft Certification Service ALS Airworthiness Limitations Section AMM Aircraft Maintenance Manual APU Auxiliary Power Unit ASI Aviation Safety Inspector CH Certificate Holder CMM Component Maintenance Manual CWT Center Wing Fuel Tank DAH Design Approval Holder DET Detailed Inspection DRS Dynamic Regulatory System EA Engineering Authorization EAPAS Enhanced Airworthiness Program for Airplane Systems EAPAS/FTS Enhanced Airworthiness Program for Airplane Systems/Fuel Tank Safety EO Engineering Order ESPM Electrical Standard Practices Manual EWIS Electrical Wiring Interconnection System EZAP Enhanced Zonal Analysis Procedure FAA Federal Aviation Administration FQIS Fuel Quantity Indicator System FR Federal Register FS Flight Standards Service FTS Fuel Tank Safety GVI General Visual Inspection ICA Instructions for Continued Airworthiness MPD Maintenance Planning Document MRB Maintenance Review Board