What happened
On 12 July 2013, a Boeing 787-8, registration ET-AOP, was parked at London Heathrow Airport following an uneventful flight from Addis Ababa. The aircraft was unoccupied and electrically unpowered at the time of the incident. At approximately 1534 hrs UTC, an air traffic control tower employee observed smoke emerging from the aircraft and triggered the airport crash alarm.
Upon arrival, the Airport Fire Service deployed water and foam to the aircraft. Firefighters entering the cabin through the L2 door encountered dense smoke. As they progressed toward the rear of the passenger cabin, they identified fire indicators above the ceiling panels. While a handheld Halon extinguisher was initially ineffective, the crew successfully extinguished the fire using water from hoses after moving a ceiling panel. The event resulted in extensive heat damage to the upper portion of the rear fuselage.
The investigation
AAIB investigators examined the aircraft's structure and identified significant thermal damage to the insulation and composite structure. The most intense heat was concentrated near the aircraft crown, specifically to the left of the centerline. This area contained the aircraft's Emergency Locator Transmitter (ELT) and its associated system wiring mounted to the internal structure.
Technical examination of the ELT revealed signs of disruption within the battery cells. Investigators were unable to definitively determine if the fire began due to an internal energy release within the Lithium-Manganese Dioxide batteries or via an external electrical short. The investigation noted that the ELT is designed to operate independently of the aircraft's main electrical system.
Findings
- The fire was centered on the location of the ELT and its internal wiring.
- The ELT battery cells showed indications of disruption, though the exact ignition source remains unconfirmed.
- There are no other aircraft systems in this specific area that contain stored energy capable of initiating a fire while the aircraft is unpowered.
- The incident occurred while the aircraft was parked and unoccupied, but the lack of fire detection or suppression in the overhead cabin space presents a significant safety risk for in-flight scenarios.