There are two main aircraft maintenance inspections required for Part 91 aircraft: the annual and 100 hour inspections. Whether you do both or only one depends on if you carry any passengers for hire.

Both inspections cover the same items. The difference is in the frequency of inspection and who is allowed to perform them.

In addition, there are several equipment inspections required outside of the annual and 100 hour inspections.

There is also an alternative to these inspections which requires written approval by the FAA: progressive inspections. For more information on who should use progressive inspections, check out this article by AOPA: Guide to Aircraft Inspections.

• Annual Inspection:

  • This inspection must be done within the preceding 12 calendar months. If you accomplished it on the 2nd of April, it wouldn’t be due until the 30th of April next year.
  • This inspection must be done by an A&P mechanic with an Inspection Authorization (IA).
  • If your annual inspection is beyond 12 calendar months, you will need a ferry permit to fly it to another airport.

• 100 hour Inspection:

  • If you want to carry passengers for hire other than yourself, or give flight instruction for hire, you must complete a 100 hour inspection in addition to the annual inspection.
  • This rule only applies to the person providing the aircraft, not the aircraft. So, if a flight instructor provides the aircraft and teaches the student, the 100 hours is required, but if the student owns their own plane and only hires the CFI to fly with them, the 100 hour is not required.
  • Unlike the Annual inspection, the A&P mechanic does NOT need an “Inspection Authorization.”
  • You can exceed the 100 hour limit by 10 hours, but ONLY if the extra time is used to fly the aircraft to a place where the mechanic will work on it. You can’t fly an extra 8 hours and then fly the last 2 of the 10 hours to a maintenance base. You also lose that extra time you flew to the next inspection. So, if you flew an hour to a maintenance base, you now have 99 hours until the next 100 hour inspection.
  • For a checklist of items covered on a 100 hour inspection check out this easy-to-read pdf: 100/Annual Inspection Checklist. Note: this is just an example and is not kept updated. Go to the CFR Appendix D to Part 43 for the hard-to-read official list.

• Additional Inspections:

  • Altimeter: if you want to operate in controlled space on an IFR plan, the altimeter must get checked every 24 calendar months
  • Transponder: you cannot use a transponder unless it has been tested within the preceding 24 calendar months.
  • Emergency Locater Transmitter (ELT): Installed ELTs must be inspected for “proper installation, battery corrosion, operation of the controls/crash sensor, and sufficient signal strength.” Usually it’s covered in the annual inspection because it’s required every 12 calendar months.

Resources:

The CFR covering Part 91 maintenance can be found here: Subpart E-Maintenance, Preventive Maintenance, and Alterations 91.401

The FAA also has a great pdf on inspections which you can check out by clicking here.