What happened
On June 19, 2018, at approximately 19:35 local time, a Heli-Sport CH 77 Ranabot ultralight helicopter, identified as 86QF, was performing a local flight at the Châtellerault-Targe aerodrome. The aircraft, operated for private use, was on final approach to runway 36 at an altitude of approximately 70 meters when the right-side door opened and detached from the fuselage.
The detached door struck the main rotor, causing the pilot to lose control of the aircraft. The helicopter subsequently collided with the ground and caught fire. The accident resulted in two fatalities, involving both the pilot and the passenger. The wreckage was located roughly 45 meters north of the runway 3/6 threshold.
The investigation
Investigators examined the wreckage and found that while the left door remained attached to the airframe, the right door had separated from the fuselage. Analysis of the locking mechanisms on the right door revealed that the primary handle was in the open position, and although the three locking pins and the secondary red latch were undamaged, they were not engaged. This indicated that the primary locking mechanism was either not engaged or only partially locked, and the secondary internal latch had not been used.
Video evidence captured by a witness confirmed the sequence of the door's detachment and the subsequent forward pitch of the aircraft before impact. While a witness on the ground noted that the pilot had secured the passenger in the left seat before entering the right seat, it could not be confirmed if the pilot had properly locked their own door.
Findings
- The investigation could not determine the specific reason why the door initially opened.
- The detachment of the right door led to a direct strike on the main rotor, causing damage to at least one rotor blade.
- The impact of the door with the rotor system was the primary factor in the loss of aircraft control.