What happened
On 27 October 2024, a Safair Boeing 737-800, registration ZS-ZWY, arrived at Lanseria International Airport from Cape Town International Airport. The flight, carrying 184 passengers and a crew of six, landed normally on Runway 07. However, during the subsequent taxi, the flight crew observed that significantly higher engine thrust—approximately 40% N1—was required to maintain standard taxi speeds. The aircraft eventually reached its parking bay without further incident.
During a post-flight inspection, an aircraft maintenance engineer discovered smoke emerging from the right main wheel assembly. A detailed examination of the Number 4 wheel assembly revealed structural damage, including metal deposits and surface discoloration, indicating the component had undergone intense thermal and mechanical stress.
The investigation
SACAA AIID investigators examined the wheel assembly and the flight data from the Quick Access Recorder. The investigation established that the inner wheel bearing had ceased to function. This stoppage caused the bearing sleeve to rotate within the wheel hub bearing bore, generating intense frictional heat. This extreme temperature led to the thermal embrittminet and subsequent disintegration of the inner bearing mount.
Technical reviews of the maintenance history showed that while the most recent overhaul in August 2024 had been completed without noted anomalies, the specific component-level tracking for this bearing was absent. The investigation also noted that the break torque applied during the most recent installation was not documented in the maintenance records.