Definition
Maintenance work on an aircraft that is performed incorrectly, incompletely, or with substandard practices, materials, or documentation, leaving the aircraft in a condition that does not meet the airworthiness standards required for safe flight.
Plain English
Maintenance that was done wrong, skipped a step, used the wrong part, or wasn't finished properly — so the aircraft isn't actually in the safe, working condition it should be.
Context Anchor
Seen in aviation maintenance hazard discussions, preflight findings, aircraft logbook reviews, and decisions about whether an aircraft may be returned to flight.
Derivation
Faulty' comes from the Old French 'faute,' meaning a lack, failure, or defect. In this context it points to a defect in the work itself — the maintenance has a fault built into it, even if the aircraft looks fine on the outside.
Why Pilots Care
It is a leading cause of in-flight component failures and accidents that proper inspection and adherence to procedures can prevent.
Intuition Check
Faulty maintenance does not only mean a large, obvious repair mistake. It can also be a missed step, wrong part, loose fastener, poor inspection, or bad record that leaves the aircraft unsafe.
Example Sentence 1
The accident investigation traced the engine failure to faulty maintenance, where the wrong size washer had been installed during the last inspection.
Example Sentence 2
Investigators traced the engine failure to faulty maintenance performed during the last annual inspection.