On 10 June 2014, a Boeing 737 aircraft, registered ZK-ZQB and operated by Jetconnect Limited, landed at Sydney Airport, New South Wales. During taxiing, the crew felt a slight shuddering from around the main landing gear; they also observed that they required a higher-than-normal thrust to taxi the aircraft. An inspection found that pieces of metal had fallen onto the runway and that the right, outer main wheel was leaning over. The inboard wheel half-hub had fractured into several pieces.

An examination of the fatigue failure indicated the origin most likely occurred in the area of the bearing bore radius. The wheel manufacturer examined the failure and concluded it was likely that the fatigue crack initiated in the stress-concentrated, transition region between the bearing bore wall and the circumferential radius. Ultrasonic testing of this area detected possible small fatigue cracks or origins.

Due to previous failures of wheel hubs with the same part number, service bulletins and requirements for inspection had been issued by the aircraft and wheel manufacturers. The maintenance records showed that required inspections had been performed.

The ATSB was advised by the aircraft operator that they are upgrading their fleet with carbon brakes from a different manufacturer. As a result, all current main wheel assemblies will be replaced with wheels from that manufacturer; hence, those wheels will have a different part number. The modification program of fitment with new wheels and brakes commenced in February 2015 and will be completed by the end of May 2015.

Aviation Short Investigations Bulletin - Issue 41


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