Definition
A condition in which a part, component, or system has a flaw, fault, or imperfection that prevents it from performing its intended function correctly or safely.
Plain English
Something is broken, faulty, or not working the way it should.
Context Anchor
Seen during preflight inspections, maintenance write-ups, aircraft logbooks, and equipment checks.
Derivation
From the Latin defectus, meaning 'a failing' or 'lacking.' In aviation, a defective item is one that 'falls short' of the standard required for safe operation.
Why Pilots Care
Identifying a defective item prevents flight with equipment that could fail and ensures the aircraft remains airworthy.
Intuition Check
Defective does not always mean completely broken. In aviation, an item can still work partly and still be defective if it has a fault or does not meet the required condition.
Example Sentence 1
The mechanic tagged the magneto as defective and removed it from the aircraft for repair.
Example Sentence 2
Maintenance replaced the defective circuit breaker before returning the aircraft to service.