What happened
On April 6, 2015, a Robinson R22 helicopter, registration F-GLHC, was undergoing engine start procedures for a local flight at the Plessis-Belleville airfield. The pilot had the collective and cyclic controls in the low, braked position. After performing magneto checks at 75% engine RPM and verifying the freewheel functionality, the pilot engaged the governor to maintain a constant rotor RPM.
Upon engaging the governor, the aircraft began to move toward the left. The pilot checked that the collective was fully in the low pitch position, but observed that the movements of the aircraft were increasing in intensity. In an attempt to stabilize the aircraft, the pilot pulled on the collective. When this failed to improve the situation, the pilot lowered the collective, at which point the helicopter tipped onto its left side, resulting in the destruction of the helicopter.
The investigation
The investigation focused on the sequence of events during the start-up phase and the pilot's response to the aircraft's instability. The investigation established that the pilot, who had 81 flight hours on type, was surprised by how quickly the engine RPM increased after the governor was engaged and did not reduce the throttle. The investigators also examined the potential causes of vibrations during engine start, such as ground surface imperfections or blade/damper settings.