MORE than a month after the Bo-105 helicopter crash in Long Lellang on September 8, which claimed five lives, investigators have yet to determine the actual cause of the tragedy.
In a preliminary report released today, the Air Accident Investigation Bureau (AAIB) stated that the safety investigation is still ongoing, and that the factual data gathered thus far remains at an early stage.
"Ongoing efforts to collect facts regarding flight operations, standard operating procedures, and the helicopter's maintenance history will provide the evidence needed to verify the effectiveness of existing safety safeguards and to assess any latent conditions that may have contributed to the accident," the report noted.
At this preliminary stage, the investigation has not uncovered any damage or defects related to the helicopter's airframe, its maintenance, or the pilot.
However, the report states that the helicopter's engine has been sent to the manufacturer's facility for further inspection, while the investigation into the power plant system remains ongoing.
Any implications for the airworthiness of other engines of the same type have yet to be determined.
The report further notes that an engineer from the manufacturer has joined the on-site investigation, serving as a technical expert representing the party responsible for the design and manufacture of the engine.
"A detailed examination of the remaining helicopter wreckage was conducted, with particular attention focused on the powerplant system and its associated components.
"The powerplant components that were recovered have been transported to the engine manufacturer's facility for further inspection and analysis," the report stated.
The helicopter was equipped with two Rolls-Royce 250-C20B engines; the first engine was manufactured in 1989, while the second was produced in 1976.
The AAIB noted that a 37-second video recording captured from the ground, showing the final moments of the flight, reveals a distinct plume of smoke and visible flames in the area behind the main gearbox.
However, the origin, progression, and sequence of the fire remain under investigation.
The report also indicated that an initial assessment at the crash site revealed the helicopter sustained extensive damage resulting from both the fire and the impact with the ground.
Major wreckage and related materials were discovered near the crash site, while smaller components and parts that had detached from the helicopter were also collected for further examination and analysis.
According to the report, the extent of the damage to the helicopter's airframe, engines, transmission system, flight controls, and other components remains subject to detailed inspection.
All recovered components and wreckage have been transported to Miri for further analysis.
"A detailed examination of the wreckage will be carried out to determine the nature and extent of the damage, as well as—if possible—the sequence and progression of the fire and the damage resulting from the impact with the ground," the report stated.
The AAIB further noted that the helicopter was considered airworthy at the time of the incident, holding a valid Certificate of Registration and Certificate of Airworthiness.
The report added that the findings from the detailed examination of the wreckage and the engine analysis will be incorporated into the final investigation report.
On September 8, a Bo-105 helicopter operating as part of the Flying Doctor Service and carrying five individuals crashed near the Long Lellang STOLport in Sarawak, claiming the lives of everyone on board. – October 16, 2026