What happened
On June 8, 2016, an Airbus AS350 B3e, registration F-HLEV, was conducting a flight for the purpose of extending a flight instructor's qualification. The flight was operated by a general aviation company near Sisteron Vaumeilh, France. The crew consisted of a pilot and an examiner, with the examiner acting as the student and serving as the pilot-in-command.
During the flight, the crew began a simulated hydraulic failure exercise. As the pilot initiated the procedure by switching the hydraulic isolation switch to the OFF position, both crew members experienced unusually heavy control forces. The examiner, acting as the student, noted the abnormal stiffness and requested assistance. During the subsequent attempt to resolve the issue, the pilot inadvertently pressed the accumulator test button, which caused a further depressurization of the hydraulic system. This resulted in the loss of both hydraulic assistance and the effectiveness of the tail rotor effort compensator. At a speed of approximately 75 kt, the aircraft became difficult to control, necessitating an emergency descent and landing on the runway at Sisteron Vaumeilh. The aircraft landed without damage.
The investigation
The BEA examined flight data from the Appareo Vision 1000 recorder, including video and audio, and analyzed crew testimonies. The investigation included a technical inspection of the aircraft's hydraulic system by manufacturer specialists, as well as ground tests, including a hover and flight maneuvers. No mechanical malfunctions were found in the hydraulic circuit or the control systems following the incident.