What happened
On July 16, 2018, a Tecnam P2002, registration F-HOAB, was performing a training flight at Les Mureaux aerodrome when it experienced a partial loss of engine power during the initial climb. Shortly after takeoff, the instructor notified air traffic that the aircraft was experiencing engine problems and intended to land.
Following the power reduction, the aircraft entered a level flight at approximately 180 feet before the pilot attempted a right-hand turn, likely in an effort to turn back toward the runway. During this maneuver, the aircraft lost airspeed, entered a steep bank, and subsequently stalled, resulting in a vertical impact with the ground near the aerodrome perimeter.
The investigation
The BEA investigation utilized surveillance footage from the aerodrome perimeter to reconstruct the flight path. The video analysis confirmed that while the aircraft initially maintained a climb rate of approximately 470 ft/min, the trajectory deviated from a straight line as the power loss occurred.
Investigators examined the wreckage and the engine components, specifically the Rotax 912-S2 powerplant. While the fuel pump and fuel lines were functional, a detailed inspection of the left carburetor revealed a bent diaphragm. This defect prevented the carburetor from properly regulating fuel flow, leading to a constant, reduced fuel delivery.
Findings
- The primary cause of the accident was a loss of control in flight during an attempt to execute a turn at low altitude and low airspeed.
- A mechanical defect in the left carburetor, specifically a bent diaphragm, caused a partial reduction in engine power.
- The decision to attempt a turn back to the runway was complicated by the fact that the power loss was partial rather than total, making the aircraft's performance difficult to assess immediately.
- The instructor's decision to turn back was likely influenced by the desire to avoid hitting the aerodrome's perimeter fence, despite the fact that an emergency landing straight ahead on the remaining runway length was likely possible.