After an uneventful from Addis Ababa (Ethiopia), a Boeing 787 arrived at London Heathrow Airport (England)around 06.30 lt (local time), and the return flight to Addis Ababa was scheduled to depart at 21.10 lt. After the crew and passengers had disembarked and the holds were empty the aircraft was towed to a remote stand, Stand 592, next to the fire station along a taxiway E. The aircraft was completely depowered after it was parked at the remote stand, however, the ground power cables remained connected to the aircraft when ground handlers left the aircraft at 07.30 lt.
The fire damaged aft fuselage (Source; google.com © unknown)
At 15.34 lt an employee in the ATC tower noticed smoke coming from the aircraft and immediately activated the crash alarm. Airport Fire Fighters arrived on the scene a minute later and started to apply water and fire fighting foam onto the outside of the aircraft, while one firefighter removed the ground power cables from the aircraft.
Two minutes after arriving at the aircraft (at 15,37 lt) firefighters entered the aircraft via door L2 (the second door from the front at the lefthand side of the aircraft) and encountered heavy smoke. As they moved towards the back of the aircraft the smoke became thicker, they opened cabin doors as they went through the aircraft. At the rear of the cabin, there were signs of fire between two overhead luggage bins. An unsuccessful attempt was carried out to Close up of the fire damage (©AAIB) extinguish the fire using a Halon fire extinguisher. As this was unsuccessful some ceiling panels were removed and, a now visible fire was extinguished with several pulses of water spray. A check for hotspots was carried out using a thermal-imaging camera. Damage to the aircraft was substantial, a 9.5 square meter (103 square feet) area was affected by the fire. The damage ranged from burned insulation blankets to severe structural damage, with the most severe damage adjacent to the ELT (Emergency Locator Transmitter.
Fire damage in the area of the ELT (© AAIB) The fire was investigated by the Air Accident Investigation Branch (AAIB), which was assisted by several Accredited Representatives from different States. The investigation revealed that the ground fire was initiated by the uncontrolled release of stored energy from the lithium-metal battery in the ELT. It was identified early in the investigation that ELT battery wires, crossed and trapped under the battery compartment cover plate, probably created a short-circuit current path which could allow a rapid, uncontrolled discharge of the battery. Root Cause testing performed by the aircraft and ELT manufacturers confirmed this latent fault as the most likely cause of the ELT battery fire, most probably in combination with the early depletion of a single cell. A description of the causal factors and contributing factors can be found in the AAIB report, which is available by clicking here. After extensive repairs to the aircraft, the aircraft was returned to service.
The aircraft under repair (Source Airliners.net © A.J. Best)