What happened
On 22 July 2023, a Leonardo AW189 helicopter, registration 9M-BOF, was undergoing post-maintenance testing at the UniKL MIAT hangar in Subang. The aircraft, operated by the Fire and Rescue Department of Malaysia (FRDM), was scheduled for an engine ground run and a hover check to verify main rotor track balancing.
During the taxi phase toward the designated hover test area, the crew received a "Yaw Trim Failed" warning on the cockpit display. The pilot attempted to correct the aircraft's position to align the nose landing gear with the intended takeoff path. During this maneuver, the helicopter began a continuous leftward spin. The rotation continued for approximately one and a half turns before the aircraft rolled onto its right side, causing the main rotor blades to strike the tarmac. While the aircraft sustained significant damage, all seven occupants—including the flight crew, engineers, and a student—evacuated the cabin with only minor injuries.
The investigation
AAIB Malaysia examined the flight data, CCTV footage, and the physical wreckage. The investigation focused on the sequence of events leading to the loss of control on the ground. Investigators also reviewed the maintenance history of the aircraft, which had recently undergone a period of inactivity for scheduled maintenance. The inquiry also assessed the safety of the operating environment, noting several hazards near the testing site, such as high-voltage power lines and nearby shooting range activities.
Findings
- The primary cause of the accident was the over-compensated left pedal input by the pilot in command, which triggered a rapid increase in the yaw rate and subsequent loss of control.
- The pilot misjudged the position of the nose wheel while attempting to straighten the aircraft's heading.
- The aircraft's heading was slightly offset to the right prior to the corrective maneuver.
- The pilots had not completed their required annual flight simulator recurrent training.
- There was no evidence of valid insurance coverage being carried on board the aircraft at the time of the incident.
Safety action
Following the investigation, several safety recommendations were issued:
- The aircraft operator must ensure all civil-registered aircraft carry valid insurance certificates covering the crew, passengers, and third-party liability.
- The operator is required to ensure pilots attend mandatory annual flight simulator training.
- The regulator (CAAM) was advised to review the use of uncertified aerodromes or facilities for routine operations, particularly in environments with identified hazards like high-voltage lines.