Comparison
Approved vs Acceptable Maintenance Data
The Two Terms
Approved and Acceptable Are Not Synonyms
Approved comes from 14 CFR 1.1: approved by the FAA, by a person to whom it has delegated its authority in the matter, or under a bilateral agreement with a foreign country. AC 43-210A adds that for FAA inspectors, approvals are granted only by letter, stamp of approval, operations specifications, or other official means.
Acceptable is the lower bar. The same AC says an item that must only be "acceptable to" the FAA does not necessarily need FAA review before use. The person using it should be able to show it meets the applicable rules, and if the FAA later disagrees it carries the burden of showing the item is unacceptable. The word you see in the rules is acceptable; "accepted" is shorthand, and it also appears in the major repair definition ("accepted practices"), which is a different idea.
AC 43-210A also splits data by type. Descriptive data (drawings, specifications, dimensions, materials) says what the repair or alteration is. Substantiating data (test results, computations) shows it meets the regulations. Approval status applies to both. For the operator-side version of this question, see our explainer on operator maintenance manuals under 43.13(c).
By Job
Which Data for Which Work
| Job | Data | Where it is stated |
|---|---|---|
| Maintenance, preventive maintenance, or alteration generally | The current manufacturer's maintenance manual or ICA, or other methods, techniques, and practices acceptable to the Administrator. | 14 CFR 43.13(a) |
| Minor repair or minor alteration | Data acceptable to the Administrator. FAA approval of the data is not required. | AC 43-210A para 1.5; Order 8300.16A ch. 1 para 5 |
| Major repair or major alteration | Technical data approved by the Administrator. | 14 CFR 43.7(d), 65.95(a)(1), 145.201(c)(2); AC 43-210A para 1.4 |
| Repair station returning an article to service | Applicable approved technical data or data acceptable to the FAA; approved data after a major repair or major alteration. | 14 CFR 145.201(c)(1) and (2) |
AC 43-210A also lists 121.379(b) and 135.437(b), which carry the same approved-data requirement for major work by part 121 and 135 operators. Who may approve the aircraft for return to service is a separate question answered in 14 CFR 43.7 and the certificate-specific parts; an inspection authorization holder, for example, may approve after a major repair or alteration only if the work followed technical data approved by the Administrator (65.95(a)(1)).
Major or Minor
The Classification Comes First
Everything above turns on whether the work is major. 14 CFR 1.1 defines a major repair as one that, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other airworthiness qualities, or that is not done according to accepted practices or cannot be done by elementary operations. A major alteration is an alteration not listed in the aircraft, engine, or propeller specifications that meets the same tests. Minor repairs and alterations are the ones that are not major. Appendix A to Part 43 lists examples.
The classification carries paperwork. Under 43.9(d), major repairs and alterations go on a form in addition to the maintenance record entry, and Appendix B names it: FAA Form 337, in duplicate, with a signed copy to the owner and a copy to the FAA Aircraft Registration Branch within 48 hours of return to service. A certificated repair station may use the customer's work order and a maintenance release instead for major repairs made under a manual or specifications acceptable to the Administrator. AC 43.9-1G gives the form's instructions. For a worked example of where the line falls on structure, see the structural repair manual.
How Data Gets Approved
Six Routes to Approved Data
The person doing the major work is responsible for obtaining the data and submitting it for approval (AC 43-210A para 1.6). These are the sources and routes the FAA material describes.
- The type certificate and its data sheet
- AC 43-210A lists the type certificate data sheet among its possible sources of approved data for major repairs and alterations, and points to FAA Order 8620.2 for how a manufacturer's data is applied and enforced.
- A supplemental type certificate or amended type certificate
- A major repair or alteration that is a major change to type design needs an STC or an amended TC. AC 43-210A says the field approval process is not available in those cases.
- A Designated Engineering Representative (DER) and Form 8110-3
- A DER finds that engineering data complies with the airworthiness standards and signs FAA Form 8110-3 to indicate it. 14 CFR 183.29 limits each kind of DER to structural, powerplant, systems and equipment, radio, engine, or propeller information, within the limits the FAA sets. An organization designation authorization (ODA) holder can approve data within the limits of its procedures manual.
- A field approval
- The FAA defines it as an approval by the Administrator, through an authorized aviation safety inspector, of technical data used for a major repair or alteration. It is a one-time approval for one serial-numbered aircraft. The applicant submits FAA Form 337 with a data package to the Flight Standards office, and the inspector approves by signing block 3 of the form.
- Previously approved data and approved published sources
- AC 43-210A lists other possible sources: airworthiness directives, FAA-approved portions of structural repair manuals, FAA-approved service bulletins and letters as described in AC 20-77, appliance manufacturers' manuals (unless specifically not approved by the FAA, for major repairs), and data for parts manufacturer approval (PMA) articles. Previously approved data must still be shown to apply to the new job.
- Repair and alteration data in AC 43.13-1B and 43.13-2
- AC 43.13-1B can serve as approved data for a major repair, with its chapter, page, and paragraph listed in block 8 of Form 337, only if the user finds it appropriate to the product, directly applicable to the repair, and not contrary to the manufacturer's data. AC 43-210A applies the same test to AC 43.13-2 for major alterations, and limits both to nonpressurized areas.
A DER-approved package does not always finish the job. The FAA says data approved by DERs may not be enough on its own for a major alteration involving, for example, flight manual supplements, airworthiness limitations, or instructions for continued airworthiness, and that additional approval such as a field approval or STC may then be required. Order 8300.16A adds that major alterations that are major changes in type design can be approved only by an Aircraft Certification Office or an ODA holder with STC or TC authority.
Where Manuals Sit
Manuals Are Mostly Acceptable, With Approved Parts
14 CFR 43.13(a) tells every maintainer to use the current manufacturer's maintenance manual or Instructions for Continued Airworthiness, or other acceptable methods. That makes the manufacturer's manual the default source, not a document the FAA has approved line by line. Some of its content is separately approved, such as the Airworthiness Limitations section and approved portions of the SRM; see our pieces on the instructions for continued airworthiness, the Airworthiness Limitations section, and the aircraft maintenance manual.
A repair station must keep specific documents current and accessible while work is done: ADs, ICA, maintenance and overhaul manuals, standard practice manuals, service bulletins, and "other applicable data acceptable to or approved by the FAA" (145.109(d)). The maintenance record entry itself may describe the work or refer to data acceptable to the Administrator (43.9(a)(1)). For how a repair station's own manuals fit, see repair station manual vs quality control manual, and for data tied to an STC, STC instructions for continued airworthiness.
This page describes FAA material as published; it is not legal advice. Read the text of the rule and confirm with your Flight Standards office before relying on a particular document for a particular job.
FAQ
Questions We Hear
Is the FAA word "acceptable" or "accepted"?
The rules say acceptable. 14 CFR 43.13(a), 43.9(a)(1), and 145.109(d) all use "acceptable to the Administrator" or "acceptable to the FAA." "Accepted" turns up in the definitions of major repair and major alteration ("accepted practices") and in everyday talk about "FAA-accepted" manuals. AC 43-210A explains that an item that only has to be acceptable does not necessarily need specific FAA review and acceptance before use, though the person using it should be able to show it meets the applicable rules.
Is a manufacturer's maintenance manual approved data?
Generally it is treated as acceptable data under 43.13(a), not as data the FAA has approved page by page. Some parts are approved: AC 43-210A names FAA-approved portions of structural repair manuals and FAA-approved service bulletins, and the Airworthiness Limitations section is FAA-approved. For a major repair or alteration, check that the specific data you use is approved for that purpose. When in doubt, ask your Flight Standards office.
What is FAA Form 8110-3?
The FAA's guide for designees calls it the Statement of Compliance with Airworthiness Standards. A DER signs and issues it to indicate that engineering data complies with the applicable standards. Applicants often attach one to a field approval data package, as AC 43-210A's checklist shows. AC 43-210A and the FAA field approvals page both warn that DER-approved data may not cover everything a major alteration needs.
When do I need a Form 337, and is that the same as a field approval?
No. Under 14 CFR 43.9(d) and Appendix B to Part 43, major repairs and major alterations are recorded on FAA Form 337, with a copy to the owner and a copy to the FAA Aircraft Registration Branch within 48 hours of return to service. A repair station may use a work order instead for certain major repairs made under a manual or specifications acceptable to the Administrator. A field approval is something else: it is how the FAA approves the data when you do not already have approved data, and the inspector signs block 3 of the same form.
Field approval or STC: which one applies?
A field approval covers one serial-numbered aircraft. A change to type design that applies across a product needs an STC or amended type certificate, and the FAA says the field approval route is not available for those. Order 8300.16A and its job aid list which alterations the FAA expects to go each way. Your Flight Standards office decides eligibility; this page does not.
Can I use AC 43.13-1B for any repair?
No. The AC states that it contains methods acceptable to the Administrator for nonpressurized areas of civil aircraft, only when there are no manufacturer repair or maintenance instructions, and that it generally pertains to minor repairs. For a major repair it may be used as approved data only when the three conditions in the AC are met and the reference is listed in block 8 of Form 337.
Get In Touch
Maintenance Data That Says What It Is
Tell us which maintenance publications you maintain and how their approval status is shown. We will tell you what keeping them clear and current involves.