Definition
A flaw, fault, or imperfection in an aircraft, component, or system that causes it to fall short of its required specification, airworthiness standard, or intended function. A defect may affect structure, materials, workmanship, or operation, and must be recorded and addressed before the aircraft is returned to service if it affects airworthiness.
Plain English
Something wrong with the aircraft or one of its parts — a flaw, crack, missing piece, or malfunction — that means it isn't working or built the way it's supposed to.
Context Anchor
Pilots encounter this term during preflight inspections, maintenance write-ups, aircraft logbook entries, and discussions about whether an aircraft is safe and legal to fly.
Derivation
From the Latin 'defectus,' meaning 'a falling away' or 'failure.' The sense in aviation is the same: the part has 'fallen away' from the standard it was supposed to meet.
Why Pilots Care
A defect can ground the aircraft or require immediate attention to maintain safety and regulatory compliance.
Analogy
Like a crack in a car's windshield that might spread and impair vision during driving.
Intuition Check
Do not assume a defect means only a major failure. In aviation, a small crack, loose part, worn tire, or item that does not work can be a defect if it affects the aircraft’s condition or operation.
Example Sentence 1
The pilot noted a defect in the landing light during preflight and entered it in the aircraft logbook.
Example Sentence 2
The mechanic entered the defect in the aircraft maintenance log as required by regulations.