Definition
Maintenance actions performed on an aircraft that either restore it to an airworthy condition (repairs) or change its design, configuration, or specifications from its original certificated state (alterations). Both are classified by the FAA as either major or minor, and major repairs and major alterations must be documented on FAA Form 337 and performed by appropriately certificated personnel.
Plain English
Repairs fix something that is broken or worn so the aircraft is safe to fly again. Alterations change the aircraft from how it was originally built or approved. The FAA splits both into major (significant work, requires extra paperwork and qualified people) and minor (routine work).
Context Anchor
Seen in aircraft maintenance records, logbooks, airworthiness discussions, and preflight decisions after maintenance has been performed.
Derivation
Repair comes from an older word meaning “to make ready again.” Alteration comes from alter, meaning “to change.” Together, the phrase points to two different maintenance ideas: putting something back into proper condition, or changing it from how it was originally approved.
Why Pilots Care
Proper classification and documentation of repairs and alterations are required to maintain the aircraft’s airworthiness certificate and comply with FAA regulations.
Intuition Check
Do not read this as just “fixes and changes” in the everyday sense. In FAA use, Repairs and Alterations are regulated aircraft maintenance actions that must be done, documented, and approved correctly.
Example Sentence 1
Before the first flight after annual inspection, the pilot reviewed the logbooks to see what repairs and alterations had been performed.
Example Sentence 2
Major repairs and alterations often require FAA approval before the aircraft can be flown again.