FAA Aviation Mechanic General (AMG)Aircraft Drawings, Weight and BalanceHard
An engineering drawing dimensions a shaft diameter as '0.497–0.500 in.' rather than showing a basic size with a plus/minus tolerance. What type of dimensioning method is this?
- ABilateral tolerance
- BLimit dimensioning
- CUnilateral tolerance
- DBasic dimensioning
Show answer & explanationAnswer & explanation
Correct answer: B. Limit dimensioning
Limit dimensioning states the maximum and minimum acceptable dimensions directly (e.g., 0.497–0.500), rather than a nominal size with a separate tolerance value, and is common for machined parts where a precise fit range is required.
Why the other options are wrong
- A. Bilateral tolerance shows a nominal value with variation allowed in both directions (e.g., ±0.005).
- C. Unilateral tolerance shows a single nominal value with variation permitted in only one direction (e.g., +0.005/–0.000).
- D. Basic dimensioning is not a standard tolerancing term used to describe this format.
Limit Dimensioning
A dimensioning method that specifies the maximum and minimum allowable size directly as two numbers (e.g., 0.497–0.500), without stating a separate nominal value and tolerance.
- States high limit and low limit directly
- No separate plus/minus value shown
- Common on precision machined dimensions
Memory trick: Limit dimensioning gives you the fence posts (min and max) directly, no math needed.