What happened
On May 3, 2012, a Zenair CH 601 Zodiak was conducting ultralight flight training at the Piła landing field (EPPI) as part of a flight school program. The flight involved an instructor and a student performing maneuvers on the left circuit. During the final takeoff of the session, the aircraft experienced a progressive loss of engine power, preventing it from reaching its intended altitude.
At approximately 20:05 LMT, witnesses observed the aircraft flying at a low altitude of roughly 80 meters above the treetops, heading toward the airfield. Witnesses reported hearing a loud bang, similar to the detonation of unburned fuel in an exhaust pipe, immediately followed by the engine ceasing to function. Following the engine failure, the aircraft performed a 90-degree left turn and entered a steep dive. The aircraft struck the ground vertically in a forested area, approximately 950 meters from the runway threshold. The impact triggered a fire that consumed the wreckage. The two occupants of the aircraft, the instructor and the student, sustained fatal injuries and died at the scene.
The investigation
The PKBWL investigation examined the aircraft's maintenance history, the engine configuration, and the flight path. The aircraft was equipped with a non-certified BMW motorcycle engine (1150 RS) converted for aviation use. Investigators noted that the engine's destruction and the subsequent intense fire prevented a definitive determination of the exact internal cause of the engine failure. However, the audible detonation reported by witnesses suggested intermittent failures in the ignition system.
Regarding the aircraft's safety equipment, the plane was fitted with a pyrotechnic ballistic parachute system. While the investigation determined that the altitude was sufficient to deploy the system according to manufacturer specifications, there was no evidence that the crew attempted to use it. The investigation also reviewed the flight logs, noting that the instructor was an experienced pilot with over 300 hours of total time, and the aircraft had been regularly maintained.