Definition
A repair to an aircraft, airframe, engine, propeller, or appliance that, if improperly done, could appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness, or that cannot be done by elementary operations. Major repairs must be performed by appropriately certificated personnel and documented on FAA Form 337.
Plain English
A repair serious enough that doing it wrong could make the aircraft unsafe or change how it flies. Because of that, only qualified people are allowed to do it, and the work must be recorded on an official FAA form.
Context Anchor
A pilot may see this term in aircraft maintenance records, preflight paperwork, or inspection discussions when checking whether the aircraft is legally and safely ready to fly.
Derivation
‘Major’ comes from the Latin ‘maior,’ meaning ‘greater.’ In aviation maintenance, it signals that the repair is significant enough to require formal oversight rather than routine handling.
Why Pilots Care
Determines whether the repair requires approved data, a qualified mechanic with inspection authorization, and a formal logbook entry before the aircraft can be flown.
Intuition Check
Do not read major repair as simply “an expensive repair” or “a repair that took a long time.” In FAA use, major means the repair can affect the aircraft’s safety or legal airworthy condition.
Example Sentence 1
The logbook showed a major repair to the wing spar after the hard landing, with a completed FAA Form 337 attached.
Example Sentence 2
Before the preflight, the pilot confirmed that the recent engine cylinder replacement had been completed as a major repair and properly returned to service.