What happened
On September 14, 2005, a Boeing 747-400F, registration JA01KZ, was performing a scheduled cargo flight from Amsterdam Airport Schiphol to Milan Malpensa. Shortly after takeoff, as the flight crew initiated the gear retraction sequence, the Engine Indication and Crew Alerting System (EICAS) triggered "GEAR TILT" and "GEAR DISAGREE" warnings. The crew observed via the gear synoptic display that the left-hand body gear door had failed to close.
Following the warnings, the crew requested permission from Air Traffic Control to abort the climb. Despite executing non-normal checklists and attempting to cycle the landing gear, the mechanical issue persisted. The crew subsequently returned to Amsterdam, where the aircraft landed without further incident. Upon inspection at the terminal, investigators found substantial damage to the landing gear doors and the gear/structure interface. Notably, the shock strut was found in a fully compressed state with zero inflation pressure, causing the tires to be lifted off the ground.
The investigation
Boeing engineers and repair teams investigated the mechanical failure and determined that the left-hand body landing gear had over-extended during the retraction process. This over-extension caused the tires of the gear to strike and damage the aircraft structure. The investigation into the shock strut's internal components revealed extensive damage, including fractures to the upper bearing carrier, the snubber valve, and the follower tube. The inner cylinder was also found to be bent.
Further analysis showed that the shock strut had extended approximately 12 inches beyond its maximum design limit, a movement that was only halted by the steering mechanism assembly. The investigation established that the failure sequence began when the upper bearing carrier dislodged from the inner cylinder.
Findings
Technical inspections of the removed components revealed that the upper bearing carriers had not undergone the required heat treatment. Instead, the parts were in an annealed condition. Electrical conductivity testing confirmed that the 2024 aluminum components were improperly processed. This manufacturing defect was traced back to a supplier error, which had been identified via a Notice of Escapement (NOE) from the landing gear manufacturer.