What happened
The incident occurred during the departure phase of flight from Chicago, Illinois, at O'Hare Airport. Shortly after takeoff, the aircraft experienced a mechanical failure involving the landing gear system. Specifically, the inboard left main wheel was lost during the climb.
Despite the sudden loss of a critical landing gear component, the pilot maintained control of the aircraft and elected to divert to an alternate airport. The flight proceeded to Detroit, Michigan, where the crew executed a safe landing. The aircraft sustained no damage during the emergency landing, and there were no injuries reported among the crew or any passengers on board.
The investigation
Following the incident, the National Transportation Safety Board (NTSB) conducted a detailed examination of the failed component. Metallurgical analysis was performed on the broken inboard axle assembly to determine the root cause of the failure.
The laboratory findings revealed that the axle had suffered from fatigue cracking. This type of failure typically develops over time due to repeated stress cycles, eventually leading to structural separation under load. The examination confirmed that the fatigue cracking was the primary mechanism that led to the loss of the inboard left main wheel.
Findings
The investigation concluded that the mechanical failure was due to material fatigue within the axle assembly. The loss of the wheel did not compromise the structural integrity of the remaining landing gear or the airframe sufficiently to prevent a safe diversion and landing. The absence of damage to the aircraft and the lack of injuries underscore the effectiveness of the crew's handling of the emergency situation.