Definition
An inspection of an aircraft part in which its physical measurements are checked against the manufacturer's specified tolerances to confirm it is still within serviceable limits. Measurements may include diameter, length, thickness, clearance, runout, or wear, and are taken using precision tools such as micrometers, calipers, dial indicators, and bore gauges.
Plain English
A check where a mechanic measures the actual size and shape of a part and compares those measurements to what the manufacturer says they should be, to decide if the part can still be used.
Context Anchor
Seen in aircraft maintenance manuals, inspection checklists, repair work, and logbook descriptions after a mechanic checks a part against required measurements.
Derivation
From 'dimension' (Latin dimensio, meaning 'a measuring'). The inspection is named for what it does: measure dimensions and compare them to allowable limits.
Why Pilots Care
Confirms that aircraft parts meet exact specifications so they fit and operate safely under flight loads.
Analogy
It is like checking a tire tread with a gauge instead of just glancing at the tire. The part may look acceptable, but the measurement tells you whether it actually meets the required limit.
Intuition Check
Do not read “inspection” here as only a visual look-over. A dimensional inspection means specific measurements are taken and compared with required limits.
Example Sentence 1
During the engine overhaul, the mechanic performed a dimensional inspection of each cylinder to check the bore for wear.
Example Sentence 2
After the propeller strike, a full dimensional inspection of the crankshaft was required.