What happened
On the morning of 26 March 2014, a Malindo Air ATR72-6 and registration 9M-LMH was performing a scheduled commercial flight from Subang International Airport to Terengganu International Airport. While the aircraft was climbing through 7,000 feet, the flight crew received a Master Warning indicating a fire in the number one engine.
In response to the emergency, the pilot initiated standard checklist procedures and the co-pilot issued a 'mayday' call. The crew requested an immediate return to Subang, which air traffic control granted. After discharging the onboard fire agents, the crew observed that the visible fire had subsided. The pilot then transitioned to single-engine operations, securing the affected engine and descending for an emergency landing. The aircraft touched down safely with fire rescue services on standby. There were no injuries to the passengers or crew, and all occupants disembarked the aircraft normally.
The investigation
The investigation focused on the source of the combustion and the condition of the engine components. Investigators examined the left engine nacelle, which exhibited severe fire damage. The damage extended from the engine turbine support case aftwards, affecting various components including fuel lines, hoses, wiring insulation, and the engine cowlings.
Technical reviews of the aircraft's maintenance history revealed that a scheduled replacement of 14 fuel nozzles on the number one engine had been completed in the early hours of the same day. The investigation also included a detailed analysis of the engine's fuel system components and the integrity of the fittings within the manifold.
Findings
- The engine fire was triggered by a fuel leak originating from a secondary manifold fitting at the No. 6 position fuel nozzle adapter.
- This specific fitting was found to have been tightened to a torque level significantly lower than the required specification.
- When the fitting was tested at the correct specified torque, no leakage was observed.
- Subsequent damage to the flow divider valve was attributed to the heat and fire produced during the initial event.
- No other contributing factors or external conditions were identified as causes for the fuel leak or the resulting fire.