What happened
The pilot and passenger had been dropped off to retrieve the pilot's airplane following the installation of a new Global Positioning Satellite (GPS) unit. Following takeoff, the pilot contacted a flight instructor via the Unicom frequency, reporting trim difficulties and stating an intention to head for Dayton.
Before establishing contact with the Dayton Airport, the pilot reported that the elevator trim was in a state of full down deflection, making it difficult to maintain altitude. The pilot confirmed to the instructor that the circuit breaker for the trim had been pulled. Shortly after these communications, the aircraft impacted a farm field in a near vertical attitude, resulting in fatal injuries.
The investigation
The investigation focused on the recently installed King KLN 89 GPS unit. This unit had been wired to the number one VOR and the autopilot to allow the GPS to be coupled to the autopilot system. While the repair technician stated that the system was checked on the ground and found to be operational after installation, it was determined that the technician failed to conduct a required test flight in accordance with FAR 91.407 (b) before releasing the aircraft to the pilot.