Aircraft inspections are primarily based on which time metric?

The correct choice for the basis of aircraft inspections is air time. This metric is defined as the time an aircraft spends in flight, from takeoff to landing. Inspections are typically scheduled based on this metric because it directly correlates with the operational wear and tear experienced during flight.

Understanding air time is crucial for maintaining aircraft safety and reliability. Regular inspections allow for preventive maintenance and necessary repairs to be made before they affect the aircraft's operation.

Flight time is often confused with air time, but it refers to the total time an aircraft is in operation, which includes ground operations as well. Cycle time pertains to the number of takeoff and landing sequences an aircraft undergoes, which may also influence certain checks but is not the primary metric for overall inspections. Engine time refers specifically to the operating time of the aircraft's engine and may be considered for engine-related service schedules but does not encompass the entire airframe’s maintenance needs as effectively as air time does.