From SKYbrary Wiki
| Event Details | |
|---|---|
| When | July 2013 |
| Event Type | AW, FIRE, LOC |
| Day/Night | Day |
| Flight Conditions | On Ground - Normal Visibility |
| FIRE | |
|---|---|
| Tag(s) | Fire-Electrical origin |
| LOC | |
|---|---|
| Tag(s) | Airframe Structural Failure |
| Outcome | |
|---|---|
| Damage or injury | Yes |
| Aircraft damage | Major |
| Causal Factor Group(s) | |
|---|---|
| Group(s) | Aircraft Technical |
| Safety Recommendation(s) | |
|---|---|
| Group(s) | Aircraft Airworthiness |
| Investigation Type | |
|---|---|
| Type | Independent |
Description
On 12 July 2013, a Boeing 787-800 being operated by Ethiopian Airlines had been parked out of service for several hours and was unoccupied when an employee in the ATC TWR observed smoke coming from the aircraft and activated the crash alarm. The immediately attending RFFS found the aircraft to be full of smoke and fire present in the roof area of the rear fuselage. This was extinguished but not before the aircraft had sustained extensive heat damage to the area of the fire with significant resultant effects on the aircraft insulation and structure.
Investigation
Although the incident did not occur in circumstances which automatically required an independent investigation in accordance with ICAO Annex 13, the Chief Inspector of the UK AAIB deemed, under his nationally defined powers, that it was ?appropriate to treat the occurrence as a serious incident and to invoke the protocols of ICAO Annex 13 with regard to the participation of other interested States?.
It was established that the aircraft had landed at Heathrow earlier the same day after an uneventful scheduled passenger flight from Addis Ababa and taxied to a Terminal 3 gate for passenger disembarkation, arriving there at approximately 0540. Later, it was towed to a remote Terminal 5 parking stand adjacent to one of the airport fire stations where the aircraft was subsequently secured after an engineer on the flight deck had visually confirmed that the ground electrical power, although remaining connected, was no longer available to the aircraft.
Nearly ten hours after the arrival at Terminal 3 for passenger disembarkation, the reported signs of fire were investigated by fire fighters who had initially discharged water and foam onto the aircraft and disconnected the ground power cable. They had then entered the aircraft at door L2 equipped with breathing apparatus and had encountered thick smoke. ?As they moved to the rear of the aircraft the smoke became denser so they opened further cabin doors to clear the smoke. At the rear of the passenger cabin they observed indications of fire above the ceiling panels. They attempted to tackle the fire with a handheld Halon extinguisher but this was not effective, so they forcibly moved a ceiling panel and tackled the fire with water from hoses? which was effective and led to the fire being extinguished.
Detailed examination of the damaged area by the Investigation team found that the greatest heat damage, and highest temperatures, had been centred close to the crown of the rear fuselage to the left of the aircraft fore-aft centre line. This location was seen to correspond to the worst externally visible damage, where ?blackened and peeling paint and damage to the composite structure? could be seen. It was noted that this area ?(coincided) with the location of the aircraft Emergency Locator Transmitter (ELT) and its associated electrical wiring which is mounted internally on structure close to the aircraft skin? and that ?there (were) no other aircraft systems in this vicinity which, with the aircraft unpowered, contain stored energy capable of initiating a fire in the area of heat damage?.
The Honeywell International ELT Model RESCU406AFN installed on the aircraft was noted to contain chemical batteries with a Lithium-Manganese Dioxide (LiMnO2) composition to allow the device, as required, to operate in an emergency situation entirely independently of the aircraft electrical power system.
Detailed examination of the ELT showed ?some indications of disruption to the battery cells? but it was not clear ?whether the combustion in the area of the ELT was initiated by a release of energy within the batteries or by an external mechanism such as an electrical short?. It was observed that in the case of an electrical short circuit, the batteries powering the device could provide a means for ignition and then suffer damage in the subsequent fire.
It was found that ?the ELT manufacturer has produced some 6000 units of this design which are fitted to a wide range of aircraft? and that the Incident being investigated has so far been ?the only significant thermal event? in service.
A Special Bulletin S5/2013 detailing the initial findings of the Investigation was published on 18 July and contained two Safety Recommendations as follows:
- that the Federal Aviation Administration initiate action for making inert the Honeywell International RESCU406AFN fixed Emergency Locator Transmitter system in Boeing 787 aircraft until appropriate airworthiness actions can be completed. [2013-016]
- that the Federal Aviation Administration, in association with other regulatory authorities, conduct a safety review of installations of Lithium-powered Emergency Locator Transmitter systems in other aircraft types and, where appropriate, initiate airworthiness action. [2013-017]
The Bulletin stated that these Safety Recommendations were issued because ?large transport aircraft do not typically carry the means of fire detection or suppression in the space above the cabin ceilings and had this event occurred in flight it could pose a significant safety concern and raise challenges for the cabin crew in tackling the resulting fire?.
The Investigation is continuing.
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