A fatigue crack in a nose wheel component led to the wheels-up landing of a Beechcraft B200 King Air at Williamtown earlier this year, according to the ATSB.
VH-XDV departed Williamtown, NSW, on 13 May on a passenger-carrying flight to Lord Howe Island when the pilot heard "mechanical crunching noises" as the wheels came up. Red lights on the panel confirmed the wheels had not retracted.
The emergency gear extension system failed to get the wheels down and ATC confirmed from the ground that the wheels were hung up. After circling for more than three hours and a diversion to Hawks Nest to escape weather, the pilot executed a wheels-up landing onto the runway at Williamtown.
The aircraft sustained only minor damage and none of the three people on board were injured.
“Detailed examination of the steering link at the ATSB’s technical facilities in Canberra, including with the use of a scanning electron microscope, identified a pre-existing fatigue crack on the fracture surface, which had initiated from a surface flaw,” said ATSB Director Transport Safety Stuart Macleod.
"When the steering link fractured, either during take-off or the gear retraction sequence, the nose wheel was able to rotate beyond its normal operational limits, and a significant left rotation led the nose gear shimmy damper to become jammed against a door hinge within the nose wheel well.”
During the ATSB investigation, manufacturer Textron Aviation advised the ATSB that it was not aware of other instances of this specific issue, and a search of the ATSB database also failed to identity related incidents.
“Nonetheless, King Air B200 operators and maintainers should be aware that while scheduled maintenance inspections require general inspection of the nose wheel steering parts, they do not call for a detailed inspection for cracks – such as the one which precipitated this failure,” Macleod said.
The operator has since done dye penetrant tests on its other B200 nose gear hardware and found no similar defects.
The full report is on the ATSB website.