The AAIB, which emphasised that the cause of the accident will only be released in the final report, said the unsafe actions of both the pilot and the engineer introduced potential hazards.
Hot refuelling involves the filling up of an aircraft’s fuel tank with the engines running.
“The helicopter was hovering with its rotor blades still running while moving closer to the ground engineer, who was positioned directly beneath the blades.
“This is a direct violation (of the safe working procedures) which mandate that crew members must wait at a safe distance from the landing point,” AAIB said in the report published on its website.
In the incident, the 44-year-old engineer was struck by the blade and was confirmed dead at the scene. The pilot escaped unharmed.
The report also said the refuelling crew should only approach the helicopter after receiving a clear instruction (thumbs-up) from the pilot.
However, it said, the engineer was already positioned beneath the helicopter while it was still hovering and approaching for landing.
The helicopter, operated by Indonesian firm PT Zaveryna Utama, had been engaged in aerial work for Tenaga Nasional Bhd’s transmission tower construction project.
The report said that on the day of the accident, the helicopter was returning to the landing site for refuelling when it lost control while hovering above the ground.
It said the aircraft’s skid partially made contact with the landing surface, causing it to topple and catch fire with the rotor blades hitting the engineer.
“In this case, the absence of a safety officer from the lessee (Malaysia Helicopter Services) at the site to supervise the hot refuelling process contributed to crew complacency, further increasing operational risks,” it said.
The report also said that when the aircraft owner fails to comply with safety regulations, it is the lessee’s responsibility to oversee and monitor operations to ensure adherence to established requirements.
AAIB said the report contains statements of facts which have been determined up to the time of issue.
It said it must be regarded as tentative and is subject to alteration or correction if additional evidence becomes available.