Cadet Mark 10
Maintenance Repairman; Maintenance Powerplant; Maintenance Inspection Authority; Maintenance Airframe; Maintenance Avionics
Maintenance Avionics 1; Maintenance Inspector 20; Maintenance Repairman 1; Maintenance Technician 34
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Ground Event / Encounter Other / Unknown
Flight Crew Landed in Emergency Condition; Flight Crew Inflight Shutdown; General Maintenance Action
Aircraft; Human Factors
This aircraft had the engine overhauled by a shop on our field; and was delivered to a second shop which installed the engine and propeller on the aircraft. The airplane was brought to me to complete the annual inspection. During the aircraft inspection the engine installation was evaluated; inspected with no defects observed. At the time of my inspection the throttle linkage was installed; bolted and cotter keyed. The aircraft went back to the shop which originally installed the engine for a new generator to be installed. This action would not have tampered with the throttle linkage. The plane arrived back at our shop where I completed final checks; and engine operations with no defects observed. Several people during this time frame witnessed the cotter key installed. The aircraft flew about 7 hours prior to throttle linkage disconnecting on takeoff. The aircraft completed an off field landing with no injuries or damage to the aircraft.The conclusion of myself and the other shop is that when the cotter key was installed it cracked allowing over time and engine vibration to fail. This caused the cotter key to fall out and the nut to back off from vibration. Also; the aircraft being worked on at several different shops could have effected quality assurance. In the future I will not have aircraft that are being worked on in several different shops at the same time. Also; more attention to detail may have caught the cotter key being cracked when the engine was installed. Tamper seal was applied to these bolts after installation; which may have allowed the damaged cotter key not to have been seen by me during my inspection.
Technician reported that seven hours after completing an annual inspection; a Mooney M-10 throttle disconnected resulting in an off field landing.