There is a bit of confusion over when 100 hour inspections are required. Even AOPA is a bit confused.
The FARs covering inspections are discussed in this post. The language covering 100-hour inspections needs to be read carefully. I can’t find the FAA opinion referenced in the following discussion, but it emphasizes the wording of the FAR. For our Cherokee, anyone can providing instruction—though if they are smart they’ll be on our insurance policy. Learning Fundamentals is providing an aircraft. No 100-hour inspection is required. Same thing is true if you use your own aircraft and receive instruction.
In addition, for our Cherokee, the insurance policy explicitly forbids commercial operations. We do not allow carrying a person for hire. Therefore, no 100-hour inspection is required.
I found a clarification letter fron the FAA at Aviation Banter.
May 3, 1984
Mr. Perry Rackers
Jefferson City Flying Service
Dear Mr. Rackers
This is in reply to your request of May 1, 1984, that we render an opinion regarding the applicability
of the 100-hour inspections requirement of Section 91.169(b) of the Federal Aviation Regulations to rental aircraft.
Section 91.169(b) of the Federal Aviation Regulations provides that, except as noted in Section 91.169(c),
a person may not operate an aircraft carrying any person, other than a crewmember, for hire, and may
not give flight instruction for hire in an aircraft which that person provides unless, within the previous 100
hours of time in service, the aircraft has received either an annual or a 100-hour inspection.
If a person merely leases or rents an aircraft to another person and does not provide the pilot, that
aircraft is not required by Section 91.169(b) of the Federal Aviation Regulations to have a 100-hour i
nspection. As noted above, the 100-hour inspection is required only when the aircraft is carrying a
person for hire, or when a person is providing flight instruction for hire, in their own aircraft.
If there are any questions, please advise us.
Joseph T. Brennan
Associate Regional Counsel
Also from the, FAA-H-8083-25B Pilots Handbook of Aeronautical Knowledge
All aircraft under 12,500 pounds (except turbojet/ turbopropeller-powered multi-engine airplanes and turbine powered rotorcraft), used to carry passengers for hire, must receive a 100-hour inspection within the preceding 100 hours of time in service and must be approved for return to service. Additionally, an aircraft used for flight instruction for hire, when provided by the person giving the flight instruction, must also have received a 100-hour inspection. This inspection must be performed by an FAA-certificated A&P mechanic, an appropriately rated FAA-certificated repair station, or by the aircraft manufacturer. An annual inspection, or an inspection for the issuance of an Airworthiness Certificate, may be substituted for a required 100-hour inspection.