What happened
On August 19, 2020, a Cessna FR 172G attempted a visual flight rules (VFR) departure from the Nabern/Teck landing field with three passengers. During the takeoff roll on runway 32, the aircraft failed to achieve sufficient airspeed for rotation. The aircraft reached a speed of approximately 41 knots as it exited the end of the runway.
After leaving the paved surface, the aircraft crossed an unpaved path and traversed a 160-meter meadow. The aircraft continued through low vegetation until it reached a parking area, where it collided with a parked car. The impact pushed the vehicle approximately 90 degrees and caused the aircraft to rotate 180 degrees before coming to a halt. The collision resulted in one serious injury and three minor injuries among the occupants. The aircraft also sustained significant damage, and three parked cars were damaged in the incident.
The investigation
The BFU investigation focused on the aircraft's performance, the fuel system, and the pilot's procedures. Investigators analyzed video footage from a witness and photos from a police helicopter to reconstruct the takeoff roll. The investigation included a chemical analysis of fuel samples taken from the aircraft's tanks, which revealed the presence of unleaded automotive gasoline (MOGAS) rather than the required AVGAS 100 LL.
Technical examination of the engine revealed heavily fouled and oiled spark plugs, suggesting uneven combustion. The electrical fuel pump showed signs of membrane hardening, likely due to the use of incompatible fuel. Furthermore, the investigation found that the pilot had not performed a takeoff performance calculation and was not utilizing the manufacturer's standard checklists, relying instead on internalized procedures and an unofficial, typewritten checklist.
Findings
- The primary cause of the accident was the failure to initiate a takeoff abort following a loss of engine power during the takeoff roll.
- The loss of engine power was likely caused by the use of unapproved and contaminated automotive gasoline, which may have compromised the fuel flow through the injection system.
- The pilot's failure to use standard checklists likely prevented him from monitoring critical engine parameters, which could have increased his awareness of the power loss.
- The pilot's reliance on experience led to the omission of essential takeoff performance calculations and the use of non-standard procedures.
- The use of MOGAS, which lacks the necessary anti-knock properties of AVGAS, and the potential introduction of contaminants via canister refueling, contributed to the engine's degraded performance.