What happened
On October 19, 2009, an IL 76 TD, registration EK76754, operated by Ayk Avia Airline, was performing a takeoff roll on Runway 12 at Sharjah International Airport. During the acceleration phase, the pilot-in-command experienced intense vibrations. At a speed of approximately 155 km/hr, the crew initiated an aborted takeoff, deploying thrust reversers to decelerate the aircraft.
After exiting the runway via Taxiway D, the crew requested to return to their departure stand due to technical issues. Upon arrival, it was discovered that the left aft inboard main landing gear wheel had disintegrated, leaving a portion of the hub attached to the axle. The detached tire was located roughly 10 and 100 meters from the aircraft's final stopping point. The debris from the separation struck the left wing root fairing, causing a significant dent and a structural cut. There were no injuries to the 7 crew members on board.
The investigation
Investigators examined the wreckage and the flight recorders to determine the cause of the mechanical failure. Analysis of the fractured hub revealed two distinct zones: a fatigue zone characterized by beach marks and an overload zone. This indicated that a crack had been propagating through the metal for some time before the final, sudden failure.
Furthermore, the investigation reviewed the functionality of the aircraft's flight recorders. It was determined that the cockpit voice recorder and the vertical load/vibration recorder contained no data relevant to the incident. The flight data recorder was also found to be partially non-functional, failing to record airspeed and specific engine parameters. The investigation also looked into the maintenance and inspection protocols for the aircraft's landing gear components.
Findings
- The primary cause of the incident was the fracture and disintegration of the left inboard aft wheel due to progressive, undetected fatigue stress.
- The fatigue crack was sufficiently old that it should have been detectable through proper inspection techniques.
- The inspection and maintenance program for the wheel hubs was insufficient to identify the developing fatigue.
- Maintenance and inspection of the aircraft's flight recorders were inadequate, preventing the collection of critical data during the event.
- There was no evidence of foreign object debris (FOD) on the runway or taxiway that contributed to the failure.