Event Details

Title:Nose gear cylinder failure while taxiing, Boeing 747-367, AP-BFV
Micro summary:While taxiing, this Boeing 747-367 experienced a nose gear cylinder fracture.
Event Time:2002-12-07 at 2040 UTC
File Name:2002-12-07-UK.pdf
Publishing Agency:Aircraft Accident Investigation Board (AAIB)
Publishing Country:United Kingdom
Report number:EW/C2002/12/01
Site of event:Taxi, London Heathrow
Departure:London Heathrow Airport, London, England, United Kingdom
Destination:Allama Iqbal International, Lahore, Pakistan
Airplane Type(s):Boeing 747-367
Flight Phase:Taxi
Operator(s):PIA - Pakistan International Airlines
Type of flight:Revenue
Serious Injuries:0
Other Injuries:0
Executive Summary:The aircraft was taxiing for departure when the crew heard a bang, the aircraft nose pitched down significantly and moments later the 'STAB TRIM' caption on the master warning panel illuminated. The commander cancelled the departure and taxied the aircraft back to a stand without further incident. A subsequent engineering examination revealed that the nose landing gear outer cylinder had suffered a circumferential fracture and a large section of the cylinder material had been ejected onto the taxiway. A metallurgical examination concluded that the fracture had occurred as the result of fatigue initiating at the base of a groove at the upper edge of the internal diameter (ID) seal band. The fracture had propagated through approximately half of the cylinder wall thickness prior to the final failure. The groove, square shaped in cross section and of an appearance that it had been made by a rotating cutting wheel, was machined into 70% of the internal circumference. The outer cylinder had been overhauled once since original manufacture during which rework in the area of the ID Seal had been carried out.
Learning Keywords:Operations - Bang, pop, crack, sizzle!
Operations - Maintenance
Systems - Landing Gear
Systems - Landing Gear - Nose Gear Collapse


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