What happened
On 15th August 2018, a Robinson R66 helicopter, registration 9M-RML, was conducting a familiarization flight at Sultan Abdul Aziz Shah Airport in Subang. The flight involved a pilot in command, who was a qualified flight instructor, and a passenger holding a lapsed private pilot license. Following several successful circuit and quick-stop exercises, the crew proceeded to a grass area adjacent to taxiways Oscar and Sierra to perform sloping ground maneuvers.
While attempting a takeoff from a slope with the right skid elevated, the aircraft began to drift rapidly to the right as it left the ground. In an attempt to correct this movement, the pilot in command applied an abrupt and excessive left cyclic input. This sudden maneuver caused the main rotor blades to tilt downward, striking the upslope ground at high speed. The impact triggered an uncontrolled clockwise spin of the fuselage, which eventually impacted the ground at a 90-degree angle from its original heading. Both occupants escaped the wreckage, with the pilot in command sustaining minor injuries.
The investigation
AAIB Malaysia examined the wreckage and the circumstances surrounding the maneuver. The investigation focused on the mechanics of the takeoff and the pilot's reaction to the aircraft's drift. Investigators noted that the grass area used for the exercise was not a formally designated training site and featured a slope between 8 and 12 degrees, exceeding the recommended maximum of 5 degrees for such exercises.
Furthermore, the investigation looked into the cockpit environment, noting that no pre-flight briefing had been conducted prior to the sortie. The investigators also analyzed the interaction between the two occupants, specifically how the instructor's sudden intervention without a clear communication of control transfer contributed to the aggressive control inputs.