What happened
On November 6, 2002, a Luxair Fokker 27 Mk050, registration LX-LGB, was performing an approach at Luxembourg airport. During the final approach phase, following the extension of the landing gear, the aircraft experienced a sudden and catastrophic change in flight characteristics. The sequence of events led to an uncontrolled descent and impact, resulting in the destruction of the aircraft.
The investigation
The AET investigation focused on the flight path, the mechanical state of the engines and propellers, and the cockpit environment. Investigators examined the flight data recorder (DFDR) and cockpit voice recorder (CVR) to reconstruct the descent and approach. A significant portion of the investigation involved analyzing the propeller regulation systems and the effectiveness of the secondary stops designed to prevent improper lever positioning. The inquiry also reviewed the maintenance history and the operational procedures used by the crew during low-visibility conditions.
Findings
The investigation established that the primary cause of the accident was the inadvertent movement of the power levers from the flight idle position into the ground control range. This action caused the propellers to enter the beta range while the aircraft was still in flight, leading to an irreversible loss of control.
Contributing factors included:
- The lack of adequate protection provided by the existing version of the skid control unit.
- A failure of the secondary stops to prevent the levers from being moved into a dangerous configuration during flight.
- Ineffective safeguards in the automatic flight-idle stop system that allowed the crew to deviate from standard operational procedures without sufficient warning.