What happened
On September 17, 2020, a De Havilland DHC-1 MK22 Chipmunk departed from the Bienenfarm landing field for a series of circuit flights. Shortly after takeoff from runway 12, during the initial climb, the aircraft experienced a sudden loss of engine power. Witnesses reported hearing engine misfires, sputtering, and seeing dark smoke emanating from the exhaust.
Following the engine malfunction, the aircraft entered a right-hand turn, likely an attempt to execute a return to the airfield. During this maneuver, the aircraft's airspeed decreased significantly. The aircraft subsequently entered a stall and plummeted in a steep descent, striking the ground with its right wing and engine. The impact resulted in one fatality and one serious injury.
The investigation
The BFU investigation focused on the sequence of events following the engine failure and the mechanical state of the aircraft. Investigators examined the engine, which had been dismantled by experts in England; no specific cause for the engine malfunction could be identified. Fuel levels and the integrity of the fuel system, including filters and pumps, were checked, and fuel exhaustion was ruled out.
Regarding the flight dynamics, the investigation looked at the impact of the wind conditions and the pilot's decision-making. The investigation also considered the aircraft's configuration, noting that the center of gravity was within limits and the aircraft was in good maintenance condition. The investigation noted that the tandem seating arrangement significantly limited the rear pilot's forward visibility during the emergency.
Findings
- The primary cause of the accident was an engine failure during the initial climb phase, occurring near obstacles at the end of the runway.
- The pilot initiated a turning maneuver to return to the airfield, which led to the aircraft's airspeed dropping below the required threshold.
- The aircraft entered an accelerated stall due to an excessive angle of attack during the turn.
- The altitude at which the stall occurred was insufficient to recover the aircraft before impact.
- A tailwind component during the turn may have provided a deceptive indication of groundspeed, contributing to the loss of control.