AC 120-104

editorial update

Advisory circular · Establishing and Implementing Limit of Validity to Prevent Widespread Fatigue Damage

Approved
July 31, 2026
Last reviewed
August 4, 2026
This change
Editorial update of AC 120-104.
Cancels
AC120-104
Family
AC 120-104 · 2 versions
14 CFR parts
26, 121, 129
Cited by
2 ADs

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed August 21, 2026.

Show pages 61–72

Appendix 8 A8-21 Document Number Document Title Document Overview Submittal Date to [responsible Aircraft Certification Service office] AAC1-M1 through Mxx AAC Models AAC1-P2, -C:

Maintenance Documents for xxxxxxxx These various documents contain maintenance instructions for the airplane. They will reference the applicable LOV and WFD maintenance actions (AAC service bulletins) as necessary.

18 months after the effective date of the final rule AAC1-WFD- DIST-02 AAC Models AAC1-P2, -C:

Distribution Method for ICA This document provides details on how AAC intends to make the LOV and WFD maintenance actions (AAC service bulletins) available to owners/operators.

90 days after effective date of the final rule ALS – Airworthiness Limitations section XI. Schedule.

Identify all major milestones, including the schedule for submitting the LOV, the schedule for meeting compliance dates, and a schedule for Structures Task Group (STG) meetings if applicable.

Example:

Project Milestones: AAC proposes the following schedule based on FAA AC 26-1 (as revised) and Order 8110.104:

1. Project kick-off meeting and familiarization briefing: 14 days after effective date.

2. Compliance plan: 90 days after effective date.

3. Meeting to discuss delegation plan: 10 days after compliance plan submittal.

4. Compliance plan approval: 4 weeks after AAC submittal to the FAA.

5. Coordination and technical meeting to discuss AAC WFD evaluation methodology and operator involvement through Structures Task Group (STG) meetings: 100 days after effective date.

6. Submittal of WFD evaluation methodology: 120 days after rule effective date.

7. Coordination and technical meeting to review application of WFD evaluation methodology:

150 days after rule effective date.

8. Coordination and technical meeting to provide project status update: 6 months after rule effective date, and every 2 to 4 weeks thereafter, as necessary.

Appendix 8 A8-22

9. Coordination and technical meeting to brief the FAA on draft compliance documents:

90 days prior to 18 months after effective date.

10. Submittal of draft documents with LOV and substantiation data: 60 days prior to the 18-month compliance date.

11. FAA review of and comments on draft documents: 5 weeks after AAC submittal of draft documents to FAA.

12. Coordination and technical meeting to discuss with FAA the draft documents: 6 weeks after AAC submittal of draft documents to the FAA.

13. Submittal of documents for FAA approval: 18 months after rule effective date.

XII. Model AAC1 Part 26 Compliance Team.

Identify the name, organization, position, and roles/responsibilities of part 26 compliance team members.

Example:

Table 4 Certification Compliance Team Matrix Name Organization Position Role/Responsibility Name 1 Regulatory and Government Affairs AAC-001 Regulatory Liaison Focal for communication with responsible Aircraft Certification Service office (e.g., oversees correspondence, acts as meeting coordinator, ensures AAC compliance with applicable part 26 requirements) Name 2 Engineering – Commercial Airplanes AAC-101 Engineering Lead Technical focal for development of structural ICA Name 3 Engineering – Commercial Airplanes AAC-101 Structures Design Engineer Technical focal for design of Models AAC1-P2 and AAC1-C Name 4 Engineering – Commercial Airplanes AAC-101 Structures Maintenance Engineer Technical focal for structures engineering support to maintenance department Name 5 Maintenance – Commercial Airplanes AAC-201 Structures Maintenance Program Coordinator Maintenance planning department focal for development of Models AAC1-P2 and AAC1-C maintenance programs (including structural maintenance) Name 6 Maintenance – Commercial Airplanes AAC-201 Maintenance Program Customer Liaison Maintenance department focal for ECA/Customer Relations

Appendix 8 A8-23 XIII. Communication and Coordination Plan.

Describe proposed communication and coordination plan.

Example: Reference AC 26-1 (as revised) and Order 8110.104. AAC proposes monthly status meetings or more frequently, if required, with [responsible Aircraft Certification Service office].

The point of contact for scheduling these meetings is Name xx, who can be reached at 555-555-5555, or via email at name.xx@abc.com.

XIV. Delegation Plan.

Describe proposed delegation plan and identify the name, organization, and delegation of each designee.

Example: AAC is working to obtain authorization for its DERs with delegated functions A3 (Fatigue Analysis) and A12 (Damage Tolerance Evaluations) to support compliance findings with the applicable Part 26 regulations. We will submit a more detailed delegation plan in the near future. Our Regulatory Liaison, Name xx, will contact the responsible Aircraft Certification Service office within 10 business days after submittal of this plan to request a preliminary meeting regarding our delegation plan.

Name Organization Delegation Name 1 Engineering – Commercial Airplanes, AAC-101 Structures DER (Design) Name 2 Engineering – Commercial Airplanes, AAC-101 Structures DER (Analysis) Name 3 Engineering – Commercial Airplanes, AAC-101 Structures DER (Installations) Name 4 Maintenance – Commercial Airplanes, AAC-201 Structures DER (Maintenance) XV. Operators’ Involvement.

Describe the plan to facilitate operator involvement in the DAH’s part 26 compliance process.

Example: AAC will work with operators of Model AAC1 aircraft during the collection of in-service data as well as the coordination and review of data that AAC will be developing to support operator compliance with 121.1115 and 129.115. AAC will establish STGs to facilitate operator and regulatory authority comments. These meetings will be in addition to those identified in Section XI of this document. AAC will provide the schedule for the STG meetings at the coordination and technical meeting, which is scheduled for [insert appropriate date].

OMB Control Number: 2120-0746 Expiration Date:12/31/2027 Advisory Circular Feedback Form Paperwork Reduction Act Burden Statement: A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a currently valid OMB Control Number. The OMB Control Number for this information collection is 2120-0746. Public reporting for this collection of information is estimated to be approximately 20 minutes per response, including the time for reviewing instructions, searching existing data sources, gathering, and maintaining the data needed, completing, and reviewing the collection of information.

All responses to this collection of information are voluntary. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to:

Information Collection Clearance Officer, Federal Aviation Administration, 10101 Hillwood Parkway, Fort Worth, TX 76177-1524.

If you find an error in this Advisory Circular, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by emailing this form to the F light Standards Directives Management Officer at 9-AWA-AFB-120-Directives@faa.gov.

Subject: AC 120-104, Establishing and Implementing Limit of Validity to Prevent Widespread Fatigue D amage Date: _____________________ Please mark all appropriate line items:

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Submitted by: Date: ______________________ FAA 1320-73 (01/25) SUPERSEDES PREVIOUS EDITIONS