Smoke trail, flames offer clues to Long Lellang helicopter crash

KUALA LUMPUR: Examination of the Flying Doctor Service's Bo-105 helicopter engines, and a video of flames and smoke near the rear of its main gearbox captured during the helicopter's final moments near Long Lellang, Sarawak, could help investigators establish what happened, an aviation expert said.

This follows the release of the Air Accidents Investigation Bureau's (AAIB) preliminary report yesterday, which found no fault with the crashed helicopter's airframe, maintenance or pilot.

Universiti Kuala Lumpur Business School Associate Professor Major Dr Mohd Harridon Mohamed Suffian said a thorough examination of the engines was standard procedure to help investigators determine the likely cause of the incident.

"Dissection of aircraft components is needed to acquire the flight's wear-and-tear history, where it would tremendously aid investigators in their logical structuring of the incident.

"Stripping down the engine would allow each component to be scrutinised for patterns of malfunction and show whether its function was impeded during flight.

"The extent of damage could also be measured in detail, allowing investigators to pinpoint the nature of the incident," he added when asked on the preliminary report.

The AAIB report also stated that the engines had been sent to the manufacturer's facility for further examination, adding that any airworthiness implications for other engines of the same type had yet to be established.

The helicopter was fitted with two Rolls-Royce 250-C20B engines manufactured in 1989 and 1976.

On the AAIB's findings of a visible smoke trail and apparent flames near the rear of the main gearbox, as well as substantial fire and impact damage, Harridon said investigators would examine burn patterns and damaged components to determine where the fire started and how it spread.

"The rear section of the Bo-105 houses several critical components, including the exhaust system, fuel and hydraulic lines, tail rotor drive shaft and transmission system.

"Investigators will examine burn patterns to determine where the fire started and how it spread.

"Scorch marks and chemical traces on damaged components could also help establish the sequence of events. If the fire is intense, heat can spread quickly in different directions."

He added that the fire could affect the helicopter's flight controls, transmission and structural integrity, making it important to establish how it spread and whether it contributed to the crash.

"During an emergency, a rapid succession of problems may leave pilots with little time to react. Even if the initial signs appear minor, pilots must assess the situation carefully, as it could escalate into a more serious emergency."

In George Town, Transport Minister Anthony Loke said the final report on the helicopter crash was expected to be published within a year.

On Sept 8, a Flying Doctor Service Bo-105 helicopter carrying five people crashed near Long Lellang STOLport in Sarawak, killing all on board.