What happened
On April 10, 2011, at 15:17 local time, a Bücker Bestmann B 181 B-1 attempted a VFR flight from Dortmund Airport (EDLW) to Hamm (EDLH). The aircraft had been undergoing maintenance in a winter hangar for several months and was being ferried to its owner's base. This was the aircraft's first flight following the maintenance period.
Prior to departure, the pilot was unable to establish radio contact with Dortmund tower. However, a radio connection was possible with a nearby Cessna 150, operated by the same owner. The pilots decided to perform a formation takeoff, with the Cessna pilot acting as the communications lead for both aircraft. The Bücker Bestmann took off from runway 06, positioned to the right and behind the Cessna. After a takeoff roll of approximately 260 meters, the aircraft suddenly veered approximately 90 degrees to the left immediately after liftoff, striking the grassy area adjacent to the runway. The pilot sustained serious injuries, and the aircraft was destroyed.
The investigation
The BFU investigation examined the wreckage and the mechanical state of the aircraft. The impact site was located near the left edge of the runway. The wreckage showed significant structural damage, including a severed engine, a broken fuselage behind the cockpit, and structural failures in the wings. The propeller blades had been torn from the hub.
Investigators examined the cockpit controls and found that the elevator trim wheel was turned fully to the right in the "nose up" position and locked. Notably, the trim indicator did not accurately reflect the actual physical setting of the trim mechanism. The landing flaps were found in the extended position but were retracted at the time of the accident. The investigation also included an analysis of the engine components, specifically the spark plugs and cylinders, to check for signs of mechanical failure.