Description

On 28 July 2008, the crew flying an Airbus A321-200 departing Manchester UK were unable to raise the landing gear. The fault was caused by damage to the Nose Landing Gear sustained on the previous flight which experienced a heavy landing.

Synopsis

The following is taken from the UK AAIB official report:

"The aircraft made a hard landing, in a flat attitude, in which the nose landing gear sustained internal damage. An engineer, following the process in the Aircraft Maintenance Manual (AMM), determined that no inspections were required as the relevant recorded parameters had not exceeded the stated threshold values. On the next flight, the flight crew were unable to retract the landing gear. Subsequent investigation of this defect identified internal damage to the nose landing gear and a bent proximity switch link rod. The nose landing gear was replaced and extensive inspections conducted before the aircraft was released to service."

The Report looked at the circumstances surrounding the hard landing:

"The landing flare was initiated slightly early and the aircraft settled into a ‘float’ at approximately 10 ft above the runway (radio height). Whilst in the ‘float’, the co pilot’s sidestick briefly moved to fully forward then to fully aft. The aircraft reacted with a rapid nose down pitch and touched down in a near flat attitude. A significant bounce occurred, which was controlled by the co-pilot; a second touchdown and rollout ensued.

Three passenger service unit oxygen masks had dropped from their stowages but no other effects of the landing were apparent and no injuries had occurred.

Later the same night, the aircraft departed Manchester and the flight crew were unable to raise the landing gear and received a landing gear shock absorber fault message. The aircraft returned to Manchester and landed without further incident.

“In order to check their operation, the nose of the aircraft was jacked up, but the nose leg did not extend as expected and fluid started leaking from the assembly. Further examination and disassembly identified that the internal shock absorber assembly was severely distorted and a link rod, which connects the upper arm of the torque link to the moving proximity sensor target mounting, was bent.”

During the course of the Investigation, "discussions with the landing gear manufacturer revealed that they had previously seen similar damage to the inner cylinder of nose landing gear legs. They advised that the collapse of the inner cylinder is the direct result of very high damping pressures which act between the inner and outer cylinders, which typically occur during a very hard three point landing or a nose gear first landing. The damage only occurs when the certificated design criteria for the landing gear is grossly exceeded."

The following Safety Recommendations are made in the Report:

• "It is recommended that Airbus includes, in the appropriate publications, further information and guidance to flight crew with regard to unusual landings to ensure they are able to properly discharge their responsibilities to declare potential high load events.
• It is recommended that Airbus review the landing parameters recorded on any of their aircraft types which are able to produce a LOAD<15> [structural report automatically produced when specific landing conditions are met] report, so that a LOAD<15> report is generated whenever there is potential for damage to be caused to the aircraft and/or its landing gear following both hard/overweight landings or abnormal landings, such as nosewheel first landings.
• It is recommended that Airbus include a specific reference in the AMM to inspecting the nose landing gear proximity target link rod for damage as, due to the landing gear geometry, it is a likely indicator of full nose landing gear compression.

Related Articles

• Loss of Control
• Airworthiness
• see the details of another similar occurrence: A321, Manchester UK, 2008 (AW LOC)

Further Reading

• The full AAIB UK Report