Definition
A required inspection of an aircraft and its engine that must be performed every 100 hours of time-in-service when the aircraft is used for hire or for flight instruction provided by the owner of the aircraft. The scope of the inspection is the same as an annual inspection, but it must be signed off by a mechanic holding at least an Airframe and Powerplant (A&P) certificate. The 100-hour limit may be exceeded by up to 10 hours only to reach a place where the inspection can be done, and that excess time must be deducted from the next 100-hour interval.
Plain English
A full check of the aircraft and engine that has to be done every 100 hours of flying when the aircraft is being rented out for hire or used by the owner to give flight instruction. It looks at the same things as a yearly inspection.
Context Anchor
Seen in maintenance records, aircraft logbooks, rental aircraft scheduling, and flight school operations.
Why Pilots Care
Keeps the aircraft legally airworthy for commercial operations between annual inspections and directly affects safety and regulatory compliance.
Intuition Check
Do not read “one-hundred-hour” as 100 calendar hours. It means 100 hours of aircraft use, counted by time in service, not by days on the calendar.
Example Sentence 1
Before dispatching the trainer, the school checked the logbook and confirmed the 100-hour inspection was completed last week.
Example Sentence 2
After completing the one-hundred-hour inspection, the mechanic made the appropriate logbook entry and the aircraft was cleared for continued flight instruction.