one-hundred-hour inspection (aircraft maintenance inspection). An inspection required by 14 CFR
91.409 for FAA-certificated aircraft that are operated for hire, or are used for flight instruction for hire.
A 100-hour inspection is identical in content to an annual inspection, but it can be conducted by an aircraft mechanic who holds an Airframe and Powerplant rating, but does not have an Inspection Authorization. A list of the items that must be included in an annual or 100-hour inspection is included in 14 CFR 43, Appendix D.
one-shot rivet gun (sheet-metal working tool). A hard-hitting air hammer, used to drive large, solid aluminum alloy rivets. A one-shot rivet gun hits the rivet with a single hard blow each time the trigger is pulled. This is different from the action of an ordinary rivet gun, which delivers a continuous series of blows as long as the trigger is held down.
Aluminum alloy rivets are strain hardened by repeated hammering, and they can become so brittle they crack. To prevent this, they can be driven with a single hard blow from a one-shot rivet gun.