NTSB Identification: FTW04LA056.
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Accident occurred Saturday, January 03, 2004 in Burleson, TX
Probable Cause Approval Date: 03/30/2004
Aircraft: Pitts S-1S, registration: N9AQ
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

While landing at a private airstrip, the right main gear separated from the aircraft. Shortly after touchdown, the right gear strut dug into the grass for approximately 75 feet before the aircraft nosed over and came to rest inverted. Inspection of the amateur-built aircraft revealed that there was an old crack on the flange where it was welded to the axle nut. A new fracture had propagated from the ends of this crack around the lower axle shaft bolt, causing the other 3 remaining bolts to fracture and separate. Examination also revealed that the axle shaft had been cut off next to the backing plate flange and an axle shaft similar to what is used on a Cessna spring gear was bolted to the flange with four quarter-inch bolts. The FAA Inspector found the separated wheel with a piece of the flange still attached to it by one of the bolts. The flange was able to swivel around the bolt, suggesting that the bolt (and the 3 other bolts) was improperly torqued.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The separation of the right main gear wheel, during landing, due to the improper maintenance by unknown maintenance personnel on the right main landing gear assembly.

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