What happened
On 19 October 2016, an Airbus A319-131, registration G-EUPM, was operating a commercial passenger flight from London Heathrow to Manchester Airport. During the preceding flight sector from Newcastle, the crew noted a slight nosewheel shimmy upon landing. On the flight to Manchester, the crew experienced a loud, rhythmic vibration during the takeoff roll between 45 and 85 knots groundspeed, which they again attributed to nosewheel shimmy.
Upon landing at Manchester, the vibration returned with significant intensity during the landing roll. As the aircraft entered a rapid exit taxiway at a groundspeed of 30 kt, the nose landing gear upper and lower torque links disconnected. This caused the nosewheels to rotate approximately 95 degrees to the left, resulting in a loss of directional control. The co-pilot managed to bring the aircraft to a halt, and the commander declared a PAN to alert air traffic control of the gear failure. There were no fatalities and no injuries among the 7 crew members or 117 passengers.
The investigation
Investigators examined the wreckage and recovered debris from the taxiway, including the apex pin and nut. The investigation found that the nose landing gear axle was bent and the steering cylinder had sustained impact damage. Analysis of the sealant on the apex pin nut revealed that while the locking components had been correctly installed during a maintenance check in February 2016, a section of the sealant had been torn away.
Further examination of the ground equipment revealed that several towbarless tractors used by the operator showed witness marks on their left paddles, consistent with contact with aircraft components. A survey of other A320-series aircraft in the fleet also identified similar sealant damage on the nose landing gear assemblies.
Findings
- The separation of the nose landing gear torque links was caused by the detachment of the apex pin nut locking components.
- The loss of these locking components was likely due to contact with a towbarless tractor paddle during pushback or towing operations.
- This contact damaged the sealant and the locking bolt assembly, eventually allowing the apex pin nut to unscrew.
- The presence of nosewheel shimmy during previous flight segments was consistent with the progressive loss of torque on the apex pin nut.