Order of authority on one sheet
Where to buy
The documents
| Document | What it governs | Source, and the catch |
|---|---|---|
| AD (airworthiness directive) | A legally enforceable rule from the FAA under 14 CFR part 39, issued when an unsafe condition exists and is likely in other products of that type | Handbook p. 2-58 and glossary. Complying is not optional. |
| TCDS (type certificate data sheet) | The formal description of the aircraft: limits, certification basis, eligible serial numbers, eligible components | Handbook pp. 2-38, 2-58. It says what the aircraft is, not how to repair it. |
| Maintenance manual (AMM) | The manufacturer's recommended and acceptable procedures for maintaining or repairing the product; its Limitations section holds the life limits | Handbook pp. 2-38, 2-39. Personnel are required by regulation to follow the manufacturer's instructions. |
| SRM (structural repair manual) | The manufacturer's guideline for repairing common damage to a specific structure; acceptable repairs for specific sections | Handbook p. 2-39. Do not assume one manufacturer's methods apply to another (p. 7-35 note). |
| IPC (illustrated parts catalogue, "parts book") | The parts and hardware to use; the Handbook says to follow it with the maintenance manual | Handbook p. 2-39. The Handbook names it but does not define it. |
| WDM (wiring diagram manual) | One of the volumes a manufacturer may publish with the maintenance manual | Handbook p. 1-36. Named, not defined. |
| SB, service letter, service instruction | The manufacturer's instructions for product improvement, or to revise manuals; letters can add procedures | Handbook pp. 2-39, 2-58. An SB is not regulatory unless an AD, the airworthiness limitations, an approved inspection programme or OpSpecs make it so. |
| AC 43.13-1B | Acceptable methods and practices for inspection and repair of nonpressurized areas, only when there are no manufacturer repair or maintenance instructions | AC paragraph 1; Handbook p. 4-93. Generally minor repairs; for major repairs a basis for FAA approval only. |
Pages are FAA-H-8083-31B Vol. 1 (2023). "Manual" includes electronic as well as printed information (p. 1-36).
Who wins
The manufacturer's manual and SRM come first. 14 CFR 43.13(a), quoted in the AC (page 1) and the Handbook (p. 4-92), names the current maintenance manual or ICA, then "other methods, techniques, or practices acceptable to the Administrator". AC 43.13-1B is the second route and covers only what the manufacturer's data does not (AC paragraph 1; Handbook p. 4-93).
It must never contradict the maker. To use the AC as approved data you must have decided it suits the product, that it applies directly to the repair, and that it is not contrary to manufacturer's data. Then cite the chapter, page and paragraph in block 8 of Form 337 (p. 4-93).
If neither covers it, ask the manufacturer. Engineering support from the manufacturer is required for methods not described in the maintenance manual or SRM (p. 4-93).
An AD stands on its own. It does not rank below a manual: it is a rule to comply with (G-2).
Where to look first
The Handbook gives no search order, so this is shop practice: identify the aircraft from its data plate and the TCDS; check the ADs; then open the maintenance manual and the SRM at the revision in force (43.13(a) says current); the parts catalogue for part numbers; the SB list for anything that revises them. Only if no manufacturer repair data exists do you turn to AC 43.13-1B.
For UAV, model and homebuilt work
A kit or UAV maker's build manual is the nearest thing to an SRM, and the same order of authority applies. The approval rules differ by aircraft category and are outside this page.
Questions people actually ask
Can I use AC 43.13-1B instead of the SRM?
Only when the manufacturer has no repair or maintenance instructions for the job, and not contrary to its data (AC paragraph 1; Handbook p. 4-93).
Is a service bulletin mandatory?
Not in itself. It is regulatory only if an AD, the airworthiness limitations, an approved inspection programme or the operator's OpSpecs make it so (Handbook p. 2-58).
Which revision do I use?
The current one: 14 CFR 43.13(a) names the current manufacturer's maintenance manual or ICA.
What is the difference between the AMM and the SRM?
The AMM gives procedures for maintaining and repairing the product; the SRM is the guideline for repairing common structural damage to it (Handbook pp. 2-38, 2-39).
Limits — when NOT to use this chart
What the sources support, and no further.
- Definitions are the Handbook's. The Handbook names IPC and WDM without defining them, so no more is said here.
- No legal advice. The rule of 14 CFR 43.13(a) is quoted as the AC and the Handbook give it; approval of a given repair is for the certificating authority.
- Not covered. Experimental or military aircraft, operator manuals and parts approval.
Where to buy
Distributors coming soon.
Sources
- 14 CFR 43.13(a), Maintenance, preventive maintenance, rebuilding, and alteration (eCFR) — AC 43.13-1B, paragraph 3 (Reference); Handbook p. 4-92.
- AC 43.13-1B, Acceptable Methods, Techniques, and Practices — Aircraft Inspection and Repair (1998, with Change 1) — Paragraph 1, purpose and the three conditions for use as approved data.
- FAA-H-8083-31B, AMT Handbook — Airframe, Volume 1 (2023), Chapters 1, 2, 4 and 7 — p. 1-36, manuals; pp. 2-38 to 2-39, TCDS, maintenance manual, SRM, service information; p. 2-58, service bulletins and ADs; pp. 4-92 to 4-93, approval of repair and AC 43.13-1; glossary G-2.