What happened
On November 4, 2010, a Beechcraft C90, registration F-BVTB, was conducting a type rating training flight near Saint-Antonin-sur-Bayon, France. The flight, operated by Aéro Pyrénées, was part of a training program involving an instructor and a student. After departing from Aix-Les-Milles and performing several maneuvers near Castellet, the aircraft was cruising at approximately 4,000 feet near the Sainte Victoire mountain range.
During the flight, the aircraft's speed decreased significantly, reaching approximately 90 knots. Shortly thereafter, the aircraft entered a spin. Radar data indicated that the aircraft followed a descending trajectory with a vertical speed of approximately 6,000 feet per minute and nearly zero ground speed. The aircraft struck the ground at a high vertical velocity in a nose-down, left-turning attitude, followed by a post-impact fire that destroyed the wreckage. Both occupants were killed.
The investigation
The BEA investigation focused on the flight dynamics and the nature of the training exercise. Investigators analyzed radar data from several stations to reconstruct the final ten minutes of the flight, which revealed a period of deceleration and altitude loss prior to the impact.
Technical examinations of the engines and propellers were conducted at the CEPr de Saclay. While the left propeller appeared to be in a "feathered" position upon impact, detailed analysis revealed that both engines were functioning normally and delivering comparable power, near idle, at the time of the collision. The observed feathered position was determined to be a result of the impact rather than a mechanical failure. The investigation also examined the maintenance history, finding the aircraft's airworthiness certificate and maintenance logs to be in order.
Findings
- The primary cause of the accident was a loss of control during a low-speed, single-engine flight exercise.
- The aircraft entered a spin while flying at an altitude of approximately 4,000 feet, which was below the manufacturer's recommended margin for such maneuvers.
- There was a lack of a standardized reference method for instructors to conduct Vmca (minimum control speed) approach exercises on this aircraft type.
- The instructor's vigilance may have been reduced due to the student's high level of professional experience, and his specific instructional experience on the Beechcraft C90 could not be precisely determined.
- The investigation noted a lack of uniformity in how such engine-out exercises are practiced among instructors in France.