Hand tools and measuring devices

Question 1

What type of precision measuring instruments can be used to measure the outside dimensions of aircraft parts?

Answer 1

Outside micrometers and Vernier calipers.

Question 2

For what reasons should a micrometer be periodically calibrated?

Answer 2

If dropped, its accuracy may be affected. OR if the spindle is over-tightened, the frame may be sprung. OR continually sliding objects between the anvil and the spindle may wear the surfaces.