What happened
On 15 January 2005, an Airbus A320-214, registration G-BXKD, was performing a scheduled passenger flight from London Gatwick Airport to Sofia, Bulgaria. Approximately one minute after the aircraft became airborne, the left nose wheel detached from the aircraft. The event was observed by airport staff and reported to Air Traffic Control.
Following the incident, the crew entered a holding pattern to manage fuel levels and landing weight. After reviewing the Quick Reference Handbook (QRH) and Flight Crew Operating Manual (FCOM), the crew decided to return to Gatwick. To ensure the safety of the landing, the crew planned for a potential nose gear collapse. They performed a low-altitude flypast to allow engineers to visually inspect the landing gear configuration.
During the landing roll, the aircraft experienced a burst tyre on the right main gear and a loss of directional control, causing the nose to swing approximately 30 degrees to the left before coming to a stop. The aircraft used 2,300 metres of the available runway.
The investigation
Investigators examined the detached left nose wheel and found that while the inner bearing was serviceable, the outer bearing showed significant damage. The grease under the hub cap was chocolate brown rather than the standard bright red, indicating contamination. Analysis revealed that the grease contained high levels of water, with some samples showing up to 22.6% water content.
Detailed examination of the outer bearing revealed that the rollers had been forced under the bearing cage, causing distortion and metal transfer. The investigation established that the bearing had experienced roller end scoring, which led to increased friction, heat, and eventually the shearing of the locking bolts that secured the nose wheel to the axle.
Findings
- The primary cause of the wheel detachment was roller end scoring within the outer nose wheel bearing.
- The failure was initiated by a breakdown in the lubrication film, likely due to water contamination in the grease.
- High water content in the bearing grease increased friction, leading to excessive heat and mechanical stress on the bearing cage and components.
- The resulting torque and axial forces caused the nose wheel securing bolts to shear, allowing the wheel to detach.