A 90 day inspection is due when?

• A. The aircraft doesn't fly for 90 days
• B. The aircraft completes 90 flights
• C. The aircraft flies 90 days in a row
• D. The aircraft uses 90 gallons of fuel

Answer: (A)

Time-based maintenance like a 90-day inspection is tied to calendar time and inactivity, not how much you’ve flown. If the aircraft hasn’t flown for 90 days, the clock reaches the point where that inspection is due to check for issues that can develop even while idle—like corrosion or lubrication degradation. The other ideas (90 flights, 90 straight days of flight, or burning 90 gallons of fuel) rely on usage metrics that don’t determine when this particular check is due, because this maintenance is scheduled based on elapsed time without flight.