100hr Check vs Annual Inspection, What’s the Difference?

What’s the difference between a 100-hr check and an Annual Inspection?

Annual Inspection or 100hr check - Sky Manor Air Repair

This is a question that frequently comes up. So much so, that we felt an in depth response was necessary to properly distinguish the two.

The reality is, they are virtually the same with only one major difference. Whether it is a 100-Hr Check or an Annual Inspection the scope of what is evaluated follows the same list from the aircraft manufacturer. The difference is in how they are handled.

A 100-Hr Check is only needed if the aircraft is being used for commercial purposes. They can be performed and signed off by any qualified technician, usually an Air-frame and Power Plant (A&P) mechanic.

However, if you put lots of flying time on your aircraft, say in the neighborhood of 200 hours or more annually, it would be highly recommended to have an inspection performed at the 100 hour interval even if the aircraft is not being flown for commercial purposes.

An Annual Inspection is a yearly evaluation required by most private and commercial aircraft. There are some exemptions to this as stated in CFR 14 FAR Part 91.409.

Most aircraft will simply require an annual inspection. While the inspected components are the same as that of a 100-Hr Check, ONLY an A&P Technician with Inspection Authority Certification, or IA, can sign off on the Annual Inspection Report.

As an example, the inspection report from Piper Aircraft clearly identifies that the type of inspection being performed must be circled in the top left corner of the form. The list of covered areas is the same.

If a 100-Hr check is required for your aircraft and one should fall during the time of an annual inspection, the annual inspection can take the place of the 100-Hr check. However, a 100-Hr check does NOT meet the requirements of the Annual Inspection.

Again, this is an administrative point as to who is authorized to sign off on the inspection.

For clarification, the 100-Hr Check and Annual Inspection programs can be replaced by other approved programs. However, these are usually reserved for larger, turbine powered aircraft which goes beyond the scope of this article.

Questions or commentary? We look forward to hearing from you.

Contact Sky Manor Air Repair and Avionics
at Sky Manor Airport (N40)
48 Sky Manor Road
Pittstown NJ 08867

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