What happened
On 8 August 2011, an ATR 72-212A operated by PT. Wings Abadi Airlines was performing a scheduled flight from Polonia Airport in Medan to Meulaboh. Shortly after takeoff, while the aircraft was climbing through approximately 1,600 feet, the crew received a fire warning for the right engine. Although the second in command initially reported no visible flames, the pilot in command proceeded with emergency procedures.
There was a notable delay in the crew's response; the engine was not shut down until two minutes after the initial warning, and the fire extinguisher was not discharged until two and a/half minutes after the shutdown. This delay left the engine exposed to intense heat for an extended period, resulting in severe mechanical damage to the engine components. The aircraft eventually returned to base, and while the passengers disembarked without injury, the engine sustained significant internal damage.
The investigation
The KNKT investigation focused on the origin of the fire and the mechanical integrity of the engine. Investigators examined the engine's maintenance history and discovered that the right engine's fuel nozzle had been replaced on 15 April 2011. Detailed examinations conducted at the Pratt & Whitney Canada facility revealed that the fuel leakage was caused by a broken pre-formed packing (O-ring) located within the fuel nozzle assembly.
Findings
- The fire originated from a fuel leak caused by a broken pre-formed packing inside the fuel nozzle assembly.
- The damage to the engine was exacerbated by the delayed execution of engine shutdown and fire extinguisher discharge by the flight crew.
- The failure of the internal component was linked to improper maintenance, as the engineer did not use the specific tooling recommended by the manufacturer during the recent nozzle replacement.
- The use of incorrect tools led to an undetected tear in the packing, which eventually failed during flight.