Definition
A thin, soft wire threaded through small holes in fasteners (such as bolts, nuts, or castellated parts) and twisted in a specific pattern so that the fastener cannot loosen or back out from vibration. The wire is installed so that any tendency of the fastener to rotate loose pulls against the wire and is prevented.
Plain English
A piece of wire run through bolts or nuts and twisted tight, so that engine vibration can't shake them loose. If a bolt tries to back out, the wire holds it in place.
Context Anchor
Seen during aircraft maintenance, preflight inspections, and discussions of securing hardware on the airplane.
Why Pilots Care
Loose fasteners can cause loss of engine power or flight controls; safety wire keeps critical hardware locked in place.
Intuition Check
Safety wire is not electrical wire. Here, “wire” means a locking wire used to physically keep aircraft parts from loosening.
Example Sentence 1
During preflight, the pilot checked that the safety wire on the oil filter was intact and properly twisted.
Example Sentence 2
After torquing the exhaust clamps, the technician added safety wire to prevent vibration loosening.