Definition
Repairs to an aircraft, airframe, powerplant, 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 are not done by elementary operations. Major repairs must be performed by appropriately certificated personnel and documented on FAA Form 337.
Plain English
A serious repair to an aircraft — one big enough that, if done wrong, it could make the aircraft unsafe to fly. These repairs require qualified people to do them and official paperwork to record them.
Context Anchor
Seen in light-sport aircraft maintenance discussions, aircraft logbooks, inspection records, and questions about what work an owner, repairman, or mechanic may perform.
Derivation
Major comes from a Latin word meaning “greater.” Repair comes from a Latin word meaning “to restore.” Together, the phrase points to repair work that restores the aircraft after a more serious problem, not just a small or routine fix.
Why Pilots Care
Determines whether the owner may legally perform the work themselves or must involve a certified mechanic to keep the aircraft airworthy and the special light-sport certificate valid.
Intuition Check
Do not read “major” as simply “expensive” or “time-consuming.” In this context, “major” means the repair can affect the aircraft’s safety, legality, structure, handling, engine operation, or other important flying qualities.
Example Sentence 1
After the hard landing, the bent wing spar required a major repair, which had to be signed off by a certificated mechanic and recorded on FAA Form 337.
Example Sentence 2
All major repairs on the light-sport aircraft were logged with the required approval to maintain its special airworthiness certificate.