Incident Overview
On 26 September 2014, at approximately 09:50 local time, an Eurocopter EC120B helicopter, registration HB-ZGJ, was involved in a serious incident during a proficiency check flight at San Vittore airfield (LSXV). The helicopter was operated by Heli-TV SA and owned by Ticinavia AG. The flight was conducted under VFR as a private check flight.
Flight Sequence
The examiner and pilot met at 09:00 in Lodrino to perform the check flight for the pilot's type rating renewal on the EC120B. After a brief briefing and pre-flight preparation, the helicopter was reported to have no technical defects and functioned normally. The crew departed Lodrino at approximately 09:20 and performed various standard check flight maneuvers. Later, they proceeded to San Vittore airfield to practice emergency procedures.
The examiner instructed the pilot to execute a simulated hover autorotation. During the first attempt, the examiner turned the twist grip in the hover, and the pilot initially lowered the collective, prompting the examiner to intervene. The examiner then demonstrated the correct procedure. A subsequent hover autorotation performed by the pilot was deemed satisfactory.
During a final hover autorotation, the helicopter was in a hover at 0.8 to 1 meter above ground when the examiner turned the twist grip. According to the examiner, the pilot initially did nothing for a fraction of a second, then pulled the collective sharply and rapidly without the helicopter having descended. The helicopter rose to 1.5 to 2 meters, and rotor rpm began to decrease. The examiner reacted by opening the twist grip and taking control to land. The pilot reported that he pulled the collective only after the helicopter had descended to cushion the landing. No acoustic warning was heard. The pilot observed a left yaw rotation and saw the first limit indicator (FLI) needle briefly reach the scale edge.
Aftermath
After landing, the vehicle and engine multifunction display (VEMD) showed the yellow warning "over limit detected." The examiner then reduced engine speed to idle several times before increasing it to 100% and instructed the pilot to return to Lodrino. Upon landing and shutdown in Lodrino, the VEMD indicated a recorded torque exceedance of 139% for 2 seconds (the limit for transient rating is 110%). The examiner discussed the incident with a local company representative who also operated the helicopter, and subsequently a maintenance organization and the manufacturer were involved in damage analysis and repairs.
Damage
The entire drivetrain sustained damage. No third-party damage occurred.
The serious incident was reported to the Swiss Accident Investigation Board (SUST) on 30 September 2014.
Report Status
This summary report was prepared for informational purposes only and did not constitute a formal investigation.