Major vs Minor Repairs and Alterations: FAA Form 337 on the A&P Oral

October 27, 2026 · Primary sources checked October 27, 2026

Major-versus-minor classification starts with the definitions in Title 14 of the Code of Federal Regulations (14 CFR), §1.1, and the applicable lists in Part 43, Appendix A. Form 337 questions then add two decisions: who may approve the work for return to service, and which Appendix B recording provision applies. On the Airframe and Powerplant (A&P) oral and practical (O&P) test, a form’s name alone does not explain either decision.

14 CFR §1.1, Major repair · 14 CFR §1.1, Major alteration · 14 CFR Part 43, Appendix A · 14 CFR Part 43, Appendix B · 14 CFR §43.7(a)–(b)

What do “major” and “minor” mean in the rule?

The Federal Aviation Administration (FAA) definitions use effects on airworthiness and the way the work is accomplished. Cost, size, and how long the job takes are not among the stated §1.1 criteria. Our advice: read both branches and keep the word “or.”

14 CFR §1.1, Major repair · 14 CFR §1.1, Major alteration

“Major repair means a repair: (1) That, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or (2) That is not done according to accepted practices or cannot be done by elementary operations.”

14 CFR §1.1, Major repair

“Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications— (1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or (2) That is not done according to accepted practices or cannot be done by elementary operations.”

14 CFR §1.1, Major alteration

Section 1.1 defines the minor terms by exclusion: “Minor alteration means an alteration other than a major alteration.” “Minor repair means a repair other than a major repair.” Our advice: include both the repair definition’s “if improperly done” condition and the alteration definition’s specifications qualification in your answer.

14 CFR §1.1, Minor alteration and Minor repair · 14 CFR §1.1, Major repair · 14 CFR §1.1, Major alteration

Use Appendix A with its qualifications

Appendix A(a)(1) identifies listed airframe alterations as major “when not listed in the aircraft specifications issued by the FAA.” For example, paragraph (a)(1)(xiii) lists: “Changes to the wing or to fixed or movable control surfaces which affect flutter and vibration characteristics.” Our advice: read the introductory condition together with that item.

Part 43, Appendix A(a)(1), (a)(1)(xiii)

Appendix A(b)(1) introduces airframe major repairs involving strengthening, reinforcing, splicing, and manufacturing primary structural members or replacing them by fabrication “such as riveting or welding.” Those fabrication methods are examples. Paragraph (b)(1)(xx) lists: “Parts of the control system such as control columns, pedals, shafts, brackets, or horns.” The component examples do not erase the opening repair conditions.

Part 43, Appendix A(b)(1), (b)(1)(xx)

Who may approve the work for return to service?

Section 43.7(b) permits a mechanic-certificate or inspection-authorization holder to approve work as provided in Part 65. Sections 65.85(a) and 65.87(a) exclude major repairs and major alterations from their general airframe and powerplant return-to-service privileges, subject to each section’s paragraph (b). Authority to perform work and authority to approve it are separate checks.

14 CFR §43.7(a)–(b) · 14 CFR §65.85(a) · 14 CFR §65.87(a)

The paragraph (b) exceptions apply only to an aircraft with a special airworthiness certificate in the light-sport category, and only to major work on products that are not produced under an FAA approval. The appropriately rated mechanic must have performed and inspected the major work; the work must have been authorized by, and performed under instructions developed by, the manufacturer or a person acceptable to the FAA. Do not turn that limited exception into a general major-work privilege.

14 CFR §65.85(b) · 14 CFR §65.87(b)

Section 65.95(a)(1) allows an inspection authorization (IA) holder to inspect and approve for return to service an aircraft or related part or appliance after a Part 43 major repair or major alteration if the work used technical data approved by the Administrator. The provision excludes aircraft maintained under a Part 121 continuous airworthiness program. Section 43.7(c) separately recognizes repair-station approval as provided in Part 145.

14 CFR §65.95(a)(1) · 14 CFR §43.7(c)

Where does Form 337 enter the O&P answer?

The Airman Certification Standards (ACS) connect the reasoning to AM.I.I.K7: “Criteria and responsibility for determining whether a repair or alteration is major or minor.” Our advice: keep that classification explanation separate from describing the form used afterward. The form itself falls under AM.I.I.K5: “The purpose and use of FAA forms (e.g., FAA Forms 337, 8010-4, 8100-2, 8130-3).”

FAA-S-ACS-1, Aviation Mechanic General, Airframe, and Powerplant Airman Certification Standards, printed 14, PDF 19, AM.I.I.K5 and AM.I.I.K7

Section 43.9(d) requires the major-work form and its disposition in Appendix B in addition to the paragraph (a) maintenance entry. The form is FAA Form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance). Completing paperwork does not create an approval privilege.

14 CFR §43.9(d) · AC 43-9D (September 22, 2025; editorial update April 30, 2026), printed 11, PDF 11, 20. FAA FORM 337 · AC 43-9D (September 22, 2025; editorial update April 30, 2026), printed 6, PDF 6, 8.7.6 / Form 337 title

Under Appendix B(a), except as provided in (b), (c), and (d), the person performing major work shall execute Form 337 at least in duplicate, give a signed copy to the aircraft owner, and forward a copy to the FAA Aircraft Registration Branch in Oklahoma City within 48 hours after approval for return to service.

Part 43, Appendix B(a)

Part 43, Appendix B(b) · Part 43, Appendix B(c) · Part 43, Appendix B(d)

Advisory Circular (AC) 43-9D, Maintenance Records and FAA Form 8130-3 Return to Service, was issued September 22, 2025, with an editorial update April 30, 2026; the FAA catalog lists it Active. Paragraph 20 discusses major-work recording and points to the Form 337 instructions. The current instructions are AC 43.9-1G, Instructions for Completion of FAA Form 337, issued November 1, 2019, also listed Active. The circulars provide guidance; §43.9 and Appendix B supply the recording requirements.

FAA AC catalog: AC 43-9D, Active, September 22, 2025, Document Information / Number, Title, Status, Date issued · AC 43-9D (September 22, 2025; editorial update April 30, 2026), PDF 1 (no printed page number), Cover editorial-update date · AC 43-9D (September 22, 2025; editorial update April 30, 2026), printed 11, PDF 11, 20. FAA FORM 337 · AC 43-9D (September 22, 2025; editorial update April 30, 2026), PDF 1 (no printed page number), Purpose, Note 2 · FAA AC catalog: AC 43.9-1G, Active, November 1, 2019, Document Information / Number, Title, Status, Date issued

Use the current Appendix B destination above. The General handbook’s Form 337 discussion on printed 2-39 directs a copy to the local Flight Standards District Office (FSDO); the current Appendix B(a) says the FAA Aircraft Registration Branch in Oklahoma City. The handbook’s “only exception” sentence (printed 2-38) concerns the repair-station work order and maintenance release in Appendix B(b); paragraphs (c) and (d) also call for Form 337, so they do not contradict that sentence. For added fuel tanks in the cabin or cargo, the handbook says an additional copy must be signed and kept in the aircraft at all times; Appendix B(d) gives the exact rule.

FAA-H-8083-30B, Aviation Maintenance Technician Handbook–General (2023), printed 2-39, PDF 88, FAA Form 337—Major Repair and Alteration · FAA-H-8083-30B, Aviation Maintenance Technician Handbook–General (2023), printed 2-38, PDF 87, FAA Form 337—Major Repair and Alteration · Part 43, Appendix B(a) · Part 43, Appendix B(c) · Part 43, Appendix B(d)

Related guides

• Mechanic privileges and their limits
• Building the underlying maintenance entry
• Maintenance records oral questions
• FAA Form 8610-2 application guide
• Finding the correct rule and form

Primary sources

• 14 CFR §1.1, Major repair
• 14 CFR Part 43, Appendix A
• 14 CFR Part 43, Appendix B
• 14 CFR §43.7
• 14 CFR §65.85
• 14 CFR §65.87
• 14 CFR §65.95(a)(1)
• FAA-S-ACS-1, Aviation Mechanic General, Airframe, and Powerplant Airman Certification Standards
• 14 CFR §43.9(d)
• AC 43-9D (September 22, 2025; editorial update April 30, 2026)
• FAA AC catalog: AC 43-9D, Active, September 22, 2025
• FAA AC catalog: AC 43.9-1G, Active, November 1, 2019
• FAA-H-8083-30B, Aviation Maintenance Technician Handbook–General (2023)
• FAA form catalog: FAA 8610-2
• FAA Mechanic Test Generator FAQs, updated May 22, 2023

Before the oral

Our advice: after checking your explanation against the definitions, close the sources and rehearse three decisions aloud: the classification, who may approve the work, and how it is recorded. Review the ACS codes on your Airman Knowledge Test Report (AKTR), but do not narrow all your preparation to missed codes. The FAA Mechanic Test Generator (MTG) FAQ calls for one additional oral question per missed ACS code and at least four random questions in each section—General, Airframe, and Powerplant.

FAA Mechanic Test Generator FAQs, updated May 22, 2023, PDF 3 (no printed page number), Oral-related Questions / How is the oral portion of the test changing? · FAA Mechanic Test Generator FAQs, updated May 22, 2023, PDF 4 (no printed page number), Oral-related Questions

Say the classification and approval reason aloud.

About this guide: drafted with AI from the FAA sources listed on this page and checked claim by claim against them. Not reviewed by an A&P mechanic or DME. How we make our guides