Definition
A likely OCR or transcription error for 'Reamed fit' — a precision hole-and-fastener fit produced by finishing a drilled hole with a reamer (a fine cutting tool) so that a bolt, pin, or bushing seats with a controlled, very close clearance. In aviation maintenance, a reamed fit is used where the joint must carry shear loads, resist movement, and hold accurate alignment.
Plain English
A bolt or pin hole that has been finished with a special tool to make it exactly the right size, so the fastener fits snugly with almost no play.
Context Anchor
Seen in aviation maintenance when a mechanic is preparing or checking holes for bolts, pins, bushings, or other fitted parts.
Derivation
‘Reamed’ comes from the Old English ryman, meaning to widen or make room. A reamer doesn’t drill a new hole — it cleans up and sizes an existing one. The word ‘fit’ here refers to how tightly two parts go together. So a reamed fit is literally a fit produced by widening the hole to a precise size.
Why Pilots Care
On critical structural and engine attachments, a sloppy hole lets the fastener move under load, which leads to wear, fatigue cracks, and eventual failure. A proper reamed fit keeps the joint tight and the load path predictable.
Analogy
It is like drilling a rough hole in wood and then carefully finishing it so a peg seats cleanly without wobbling or forcing it in.
Intuition Check
Do not read “fir” here as the tree or wood type. In this context, the intended maintenance idea is almost certainly “fit,” meaning how accurately one part sits in or against another.
Example Sentence 1
The engine mount bolts require a reamed fit, so the technician finished each hole with a hand reamer before installation.
Example Sentence 2
After the disk was removed, several reamed fir locations showed wear that required rework.