Date: 202009
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: FBO
Operating under: Part 91
Flight plan: None
Reporter organization: FBO
Reporter function: Instructor
Reporter qualification: Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial; Flight Crew Multiengine
Human factors: Communication Breakdown; Training / Qualification
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Routine Inspection
Result: General Maintenance Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Apparently one of the flight school aircraft; a Cessna 172-L model; has been technically un-airworthy. The local mechanic shop did perform a pre-buy inspection when the flight school purchased the aircraft. The aircraft has undergone routine 100 hour inspections since the plane started working in the flight school. However; it wasn't until the most recent 100 hour inspection which was early September of this year that the local mechanic shop found that the aircraft was overdue on an Airworthiness Directive on a component on the propeller. It was overdue for about 500 hours on that particular AD. The mechanic shop was not certified to do the inspection on the propeller for that given AD for the propeller to be complied with. The flight school requested a ferry permit to fly the aircraft to the nearest propeller mechanic shop but was denied by the local FSDO. The next option was to remove the propeller and drive it to a propeller shop so that AD could be complied with. Such action was taken and the propeller shop found no defects with the propeller. The propeller was later driven back to the home airport to be placed back on the aircraft. Alas; the aircraft was complied with all known Airworthiness directives. The local mechanic shop staff admitted that they overlooked the AD. However; at the end of the day it is the owner/operator of the aircraft that is ultimately responsible for determining the airworthiness of the aircraft; which includes me; the flight instructor when using the aircraft to train student pilots. The flight school staff; meaning all the instructors and chief pilot were essentially responsible for this oversight of the airworthiness of the aircraft. I believe that the flight school staff trusted the mechanic shop to ensure the aircraft complies with all known AD's for every 100 hour inspection. The flight school has every intention to ensure the aircraft meets all inspections including ADs; and that by paying the mechanic shop for their services would suffice for ensuring the aircraft is airworthy. Over-relying on the mechanic shop in my opinion has been the root cause of this issue. I've personally shown the logbooks of the aircraft and ADs to my students prior to every checkride to show the aircraft is airworthy. I've even presented the ADs to my examiner for my CFI initial checkride. I honestly just never knew how to look up ADs or even know how to make sure that all ADs are complied with. The resolution that the chief pilot and I want to take to prevent this mishap from happening again is to learn how to look up ADs ourselves as a secondary check on top of the routine inspections done by the mechanics. Had I known that the AD wasn't complied with no one would've flown that aircraft until it is absolutely airworthy. A more thorough overview on the flight school's ADs is needed to make sure we are complying with them; and to make sure none have been overlooked. Again; the Chief pilot and I want to be able to double check AD compliance after routine inspections; and enhance communication between the instructors and mechanics.




Synopsis: Flight Instructor reported that an Airworthiness Directive had been overlooked on a flight school aircraft.