Definition
FAA Form 337 is the official Federal Aviation Administration document used to record a major repair or major alteration performed on an aircraft, airframe, engine, propeller, or appliance. It is completed and signed by the certificated person who performed and approved the work, then submitted to the FAA and retained as part of the aircraft's permanent maintenance records.
Plain English
It is the paperwork that officially records when something significant has been repaired or changed on an aircraft. The form proves the work was done properly and by an authorized person, and it stays with the aircraft's records for the rest of its life.
Context Anchor
Pilots encounter FAA Form 337 when reviewing aircraft maintenance records, checking whether an aircraft is legal to fly, or buying or renting an aircraft with past major work.
Derivation
The number 337 is simply the FAA's form-numbering reference and has no separate meaning. 'Major' in this context distinguishes substantial work — repairs or alterations that could appreciably affect airworthiness — from routine or minor maintenance, which does not require this form.
Why Pilots Care
Proper completion keeps the aircraft's airworthiness certificate valid and prevents grounding during inspections or resale.
Grounding Statement
FAA Form 337 is the paper trail for major aircraft work that must be documented beyond a normal logbook entry.
Intuition Check
Major does not simply mean expensive or difficult here. In this context, major means the FAA treats the work as significant because it can affect the aircraft’s safety, structure, performance, or operating characteristics.
Example Sentence 1
Before buying the aircraft, the pilot reviewed every Form 337 in the logbooks to understand what repairs and alterations had been made.
Example Sentence 2
The owner submitted the completed FAA Form 337 to the FAA for approval before the next annual inspection.