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a) Brief description of the occurrence

B739, Paris CDG France, 2019

Description

On 27 October 2019, a Boeing 737-900 (4X-EHE) being operated by El Al on a scheduled international passenger flight from Paris CDG to Tel Aviv as LY326 was about to begin taxiing after pushback and engine start when an under-floor hold fire was annunciated in the flight deck. Since there were no signs of fire in the passenger cabin or during an emergency services external inspection, a non-emergency disembarkation of all occupants was made. The hold concerned was then opened and fire damage sourced to the overheated lithium battery in a passenger wheelchair was discovered.

Investigation

An Investigation was carried out by the French Civil Aviation Accident Investigation Agency, the BEA. The Investigation was conducted by use of statements and reference to applicable procedures. Since the aircraft electrical power system had remained on, any relevant data on the CVR would have been overwritten and it was not downloaded.

What Happened

Following completion of the pushback from gate A38 at Terminal 2A, the aircraft was facing west on taxiway P1 with both engines running while the tug was uncoupled. The flight crew reported they were about to request taxi clearance when an AFT CARGO FIRE warning was annunciated. The prescribed response was followed with operation of the hold fire extinguishers and advice of the emergency given to ATC. The flight crew then asked the cabin crew to see if they could see any evidence of flames, smoke or heat coming from the cabin floor and the Senior Cabin Crew Member (SCCM) purser confirmed that they could not. The ARFF arrived at the aeroplane within 2 minutes and carried out an initial visual and thermal-imaging inspection and confirmed to the flight crew that no flames or smoke were externally visible. Nevertheless, the Captain decided that the passengers should be disembarked from the aircraft in its current position using steps at the front left door and asked the cabin crew to be ready to carry out an emergency evacuation if this should become necessary. Whilst this precautionary disembarkation was taking place, the flight crew stated that the same fire warning had come on and off again and towards the end of disembarkation, the cabin crew stated that they had been able to smell smoke in the cabin but were unable to see any. After all occupants had left the aircraft, the ARFF personnel opened the aft hold door and observed light smoke but could see no sign of a fire. All the luggage in the hold was unloaded to enable an inspection for signs of overheating or fire. Heat marks were found on a severely damaged foldable electric wheelchair belonging to one of the passengers which was also emanating a strong smell of burning. This wheelchair was powered by a removable lithium battery and appeared to have been damaged due to its electrical system overheating. The battery itself showed no obvious signs of damage except for a few external burn marks which corresponded to openings in the battery housing. However, a red canvas pouch which touches the battery when the chair is folded in a vertical position and is used to contain the wheelchair battery when removed for folding was found attached to the chairs handles and exhibited burn marks. Prior to the arrival of the BEA investigators, the wheelchair was handled and the battery put to one side, which meant that its position at the time of the event and the content of the pouch were not known. However, examination of the damage to both the wheelchair and the battery indicated that the latter was likely to have been in its housing on the wheelchair when it was loaded.