What happened
On 24 March 2021, an Airbus Helicopters H125, registration 9M-LEO, was involved in a serious accident at Sultan Abdul Aziz Shah Airport (WMSA) in Malaysia. The aircraft, operated by Leopad Aviation Sdn Bhd, had arrived from Sungai Lembing and was attempting to reposition itself via a high hover over Taxiway Sierra to the airport's heliport.
During the maneuver, the helicopter experienced an uncommand and rapid yaw to the left. As the aircraft continued to spin, it struck the tarmac, causing the airframe to disintegrate and the tail boom to separate. The impact was severe enough that the right-hand seat pilot and one passenger were ejected from the cabin. One passenger remained pinned under the wreckage, suffering burns, while the remaining occupants managed to exit the aircraft.
The investigation
AAIB Malaysia investigators analyzed the flight sequence using video footage from the aircraft's Vision 1000 Airborne Image Recording System. The footage revealed that after completing a 180-degree turn, the pilot struggled to arrest a leftward rotation. In an attempt to stabilize the aircraft, the right-hand seat pilot applied full left pedal input. This action inadvertently worsened the rotation, leading to an uncontrollable increase in yaw rate and the subsequent ground impact.
Findings
- The primary cause of the accident was an occurrence of Unanticipated Left Yaw, a phenomenon also known as Loss of Tail-Rotor Effectiveness (LTE).
- The application of left pedal input by the crew during the unstable state exacerbated the leftward rotation.
- The accident resulted in 1 fatality and 1 serious injury, with two other occupants sustaining minor injuries.
- The aircraft was a total loss following the structural disintegration during the impact.