Definition
A projecting rim, edge, or collar on a part used to strengthen it, guide it, hold it in position, or provide a surface for attaching it to another part, typically by bolts or rivets.
Plain English
A raised lip or rim on the edge of a part. It either stiffens the part or gives it a flat face that can be bolted to something else.
Context Anchor
Seen in aircraft maintenance descriptions, especially around engine parts, sheet metal, ducts, wheels, tubing, and mounting surfaces.
Derivation
From Old French 'flanche', meaning a side or flank. The idea is the same: a side piece sticking out from the main body of the part.
Why Pilots Care
Flanges are common joining points for high-stress and high-temperature parts, like exhaust stacks and hydraulic lines. A cracked or warped flange is a frequent finding on preflight and inspection, and it can lead to leaks, loose connections, or structural failure.
Analogy
A flange is like the lip around a jar lid or the rim around a metal bracket. The extra edge gives the part a place to grip, seal, or fasten.
Intuition Check
Do not think of a flange as a separate add-on by default. It is usually the projecting edge or lip built into a part to help it attach, align, seal, or stay strong.
Example Sentence 1
During the inspection, the mechanic found a small crack in the exhaust flange where it bolts to the cylinder.
Example Sentence 2
Clean both flange faces thoroughly to ensure a leak-free seal on the fuel drain line.