What happened
On July 30, 1967, a Piper J3C (registration HB-OUD) departed from Biel for a short recreational flight carrying one passenger. The flight path included overflights of Biel, Île Saint-Pierre, and Aarberg before the aircraft returned to the Biel airfield.
During the final approach to runway 07, the pilot attempted to execute a go-around. However, as the pilot applied power, the engine failed to respond. Unable to maintain flight, the pilot was forced to land the aircraft in a wheat field located approximately 190 meters before the runway threshold. The impact caused serious damage to the aircraft, including a broken propeller, a damaged engine, and a twisted fuselage. The pilot sustained slight injuries, while the passenger remained uninjured.
The investigation
Investigators examined the aircraft' and the engine components to identify the source of the power loss. A technical inspection of the Continental C 90-12 F engine was conducted by Transair SA, which found no mechanical defects that could explain the failure.
Fuel quality was also scrutinized; an inspection of the fuel strainer revealed no water contamination and only minimal sediment. Additionally, investigators ruled out carburetor icing due to the ambient temperatures, which were well above the threshold for icing at the flight altitude. While the technical report noted a slightly rich carburetor setting—which can cause momentary engine stumbling during rapid throttle movements—this was not considered a definitive cause for the total loss of power.
Findings
- The engine failed to respond during a go-around attempt.
- The exact cause of the engine failure could not be determined through technical examination.
- Atmospheric conditions were warm, making carburetor icing impossible.
- No significant fuel contamination was present in the system.