Definition
A protective outer covering, typically made of woven fiberglass or silicone-coated fabric, that is fitted over flexible hoses and certain wiring or components in fire zones of an aircraft engine to shield them from heat and flame for a specified period in the event of a fire.
Plain English
A heat-resistant sleeve slipped over hoses and lines near the engine so they keep working for a while if there is a fire.
Context Anchor
Seen during engine compartment inspections and in maintenance discussions about protecting hoses, fuel lines, oil lines, and wiring from heat.
Derivation
From 'fire' (the hazard it protects against) and 'sleeve' (a tube-shaped cover that slides over something). The name describes exactly what it does: a sleeve that protects against fire.
Why Pilots Care
It delays or prevents fire damage to critical lines, giving the pilot extra time to shut down systems or land safely.
Analogy
A fire sleeve is like a heat-resistant jacket around a hose or wire. The jacket is not the working part, but it helps protect the working part from damage.
Intuition Check
A fire sleeve does not put out a fire. It is a protective cover that helps the part underneath survive heat or flame exposure longer.
Example Sentence 1
During the engine inspection, the technician found a frayed fire sleeve on the fuel hose and replaced it before returning the aircraft to service.
Example Sentence 2
After the engine run-up, the mechanic inspected each fire sleeve for cracks or fluid stains.