Definition
A machining operation that produces a small, smooth, flat area around a drilled hole, perpendicular to the hole's axis, so that the head of a bolt or the face of a nut or washer seats squarely against the surface.
Plain English
Cutting a small flat circle around a hole so a bolt head or nut sits flat and square against it, instead of sitting crooked on a rough or angled surface.
Context Anchor
Seen in aircraft maintenance manuals, repair instructions, and shop work where parts are drilled and fasteners must seat correctly.
Derivation
From 'spot' (a small, localised area) and 'facing' (machining a flat face on a surface). Together it describes facing only the small spot needed around a hole, rather than machining the whole part.
Why Pilots Care
Ensures fasteners achieve full torque and sealing, preventing loosening or stress cracks in critical airframe joints.
Intuition Check
Spot-facing is not cleaning or painting a spot. It is cutting a small flat seating surface around a hole.
Example Sentence 1
The drawing called for spot-facing around each mounting hole so the bolt heads would seat flat against the casting.
Example Sentence 2
After spot-facing the bracket, the washer sat flat and the bolt torqued evenly with no gap.