What happened
On 14 April 2012, a SOCATA MS880B was conducting a training flight at EBUL Ursel Airfield to practice simulated engine failure procedures. The pilot, flying solo, had climbed to 2,500 ft AGL and initiated the exercise by reducing throttle and activating the carburetor heat. During the descent, the pilot realized the aircraft was too high and close to the runway threshold, prompting a decision to abort the exercise and perform a go-around.
Upon attempting to increase power, the engine failed to respond to the throttle opening. The pilot attempted to restart the engine using the starter, but was unsuccessful. The aircraft was forced to land in a field adjacent to the airfield. During the final approach, the right wing struck a tree, causing significant structural damage to the wings, fuselage, and nose landing gear. The pilot sustained one minor injury.
The investigation
Investigators examined the wreckage and the aircraft's fuel system to determine why the engine failed during the transition to power. While the engine was mechanically sound and the ignition system was functional, investigators discovered that the fuel level in the carburetor bowl was insufficient to feed the main nozzle.
Analysis of the fuel system revealed that the left wing tank was nearly empty, while the right tank was more than half full. The investigation also noted that the aircraft was using automotive fuel, which lacks the necessary certification for this aircraft type. Furthermore, the carburetor temperature indicator was found to be unserviceable, preventing the pilot from monitoring for potential icing.
Findings
- The primary cause of the accident was an undetected engine failure occurring during a simulation of an engine failure.
- While the exact cause could not be definitively proven, the investigation suggests the engine likely suffered from fuel starvation. This may have been triggered by uncoordinated turns (slips or skids) moving fuel away from the pump intake in a nearly empty tank.
- Carburetor icing remained a possible contributing factor due to the meteorological conditions and the use of automotive fuel.
- Several contributing factors were identified, including the pilot's failure to activate the electrical fuel pump, the selection of a low-fuel tank, and the delayed application of carburetor heat.
- The pilot's decision not to apply immediate throttle during the simulation prevented the early detection of the actual engine failure.