Description

On 1 March 2005, a Boeing 777-200 being operated by Pakistan International Airlines on a scheduled passenger flight from Lahore to Manchester experienced a landing gear fire during taxi in at destination after an apparently routine landing in normal day visibility. There were no flight deck indications of a significant fire but an emergency evacuation was recommended by attending Fire Crew and carried out. Thirty one of the 344 occupants sustained minor injuries during this evacuation and the rest were uninjured. Five firefighters also sustained minor injuries as they assisted passengers from the slides. Damage to the aircraft was minor.

Investigation

An Investigation was carried out by the UK AAIB. The landing was confirmed to have been normal.

It was established that the first awareness of a fire was a report to ATC GND from another aircraft in respect of the left main gear. The flight crew had no indications of a fire and were unaware of any problem as well as not realising that the transmission of the other aircraft was about them. The ATC GND controller observed yellow and white flames coming from the left main gear and initiated procedures for an Aircraft Ground Incident (AGI). The RFFS arrived and whilst they attempted to extinguish the flames, copious quantities of what the RFFS Watch Commander assessed as ‘smoke’ were produced and because he considered that the fire was getting out of control, he advised the aircraft commander to evacuate the aircraft. This was ordered and the right hand exits used. As the evacuation had been the subject of a number of video recordings, it was decided to investigate it in more detail.

It was found that there was visible heat damage on the left main gear where the anti-abrasion sheaths on the No 10 brake unit hydraulic pressure hose and temperature probe conduit had melted. There was also slight damage to fuselage skin adjacent to door 3R, heat damage to the No 10 tyre and to hydraulic hoses on the left main landing gear. No indications were found of any hydraulic or fuel leaks on either the left main gear leg or within the corresponding wheel bay.

Because there had been previous instances of wheel fires on this operator’s Boeing 777 aircraft upon arrival at Manchester, these incidents were re-examined and it was found that all the affected wheels had been fitted to the aircraft at Karachi, with the fires all occurring on the ‘second’ landing thereafter at Manchester. It was considered likely that, in all these incidents, solvent escaping from heated heat shields was ignited and briefly burnt, in some cases also extending to the ignition of excessive grease either on the axle or thrown onto the brake pack during the first landing. It was concluded that the most likely reason for the majority of the fires occurring at Manchester was that it is here the aircraft normally undertakes its first landing with a full payload following a wheel change at Karachi. This means that brake packs would be likely to be hotter than after landing at Lahore, with the result that the heat shields could sometimes become sufficiently hot for the entrapped solvent to escape as a vapour and ignite, probably, on contact with the hot brakes.

The Investigation determined that the probable cause of the fire, established as being in the No 10 main landing gear wheel, was:

“the maintenance practice used when cleaning the wheel heat shields. It was (considered) likely that these had been immersed in a flammable solvent, which allowed the ceramic fibre insulation material contained within to become contaminated. The fire (had) occurred on the second landing after the wheel had been fitted to the aircraft, when the brake pack temperature was likely to have been higher than on the previous landing.”

Four Safety Recommendations were made as a result of the analysis during the Investigation of the RFFS response and the evacuation which occurred:

• The Civil Aviation Authority should require at aerodromes, where the Rescue and Fire Fighting Category is 3 and above, or where an air traffic control service is provided, that a radio frequency to facilitate direct communications between an aircraft and the Airport Rescue and Fire Fighting Service, in the event of an accident or incident to an aircraft on the airfield, is made available and appropriately promulgated. (2005-092)

• The Civil Aviation Authority should require that any radio communication frequency used to facilitate direct communications between an aircraft and the Airport Rescue and Fire Fighting Service, in the event of an accident or incident on the airfield, should be recorded, in order that it may be reproduced to assist in accident and incident investigation. (2005-093)

• It is recommended that Pakistan International Airline Corporation review the training given to their cabin crews with the intention of ensuring that, in the event of an evacuation command being given by the aircraft commander, the evacuation is carried out as expeditiously as possible, irrespective of the lack of any threat to the aircraft perceived by the cabin crew. (2005-097)

• It is recommended that the Civil Aviation Authority review the advice given in CAP 168 (9th edition) in regard to aerodrome procedures for leading passengers, evacuated from an aircraft, to secure areas away from the scene of the incident and ensure that the relevant Aerodrome\Emergency orders suitably address this topic. (2005-131)

The Final Report of the Investigation was published on 5 January 2006 and may be seen in full at SKYbrary bookshelf: AAIB Bulletin: 1/2006 EW/C2005/03/01

Further Reading

• Fire Triangle
• Brakes
• Aircraft Fire Detection Systems
• Rescue and Fire Fighting Services
• Unidentified Fire On Board (OGHFA SE)
• Unexpected Events Training (OGHFA BN)