NTSB Identification: MIA08LA174
14 CFR Part 137: Agricultural
Accident occurred Tuesday, August 26, 2008 in Clarksdale, MS
Probable Cause Approval Date: 09/30/2009
Aircraft: SCHWEIZER AIRCRAFT CORP G-164B, registration: N3633S
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 applying the left brake during taxi after landing, the pilot first heard a "loud pop from the left gear" and during further brake application, the left axle and wheel assembly separated. Two MS20008H22 bolts and one AN509-616-35 screw that secure the axle to the spring leg were fractured. The failure mode of the bolts was due to fatigue, and was typical of bolts that are insufficiently torqued. The mechanic who last inspected the airplane used his own checklist and did not torque check the bolts and screw, which is required by the manufacturer's Annual/100-Hour Airframe Inspection Checklist.

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

The mechanic’s failure to torque check the axle-to-spring gear attachment bolts per the manufacturer's Annual/100-Hour Airframe Inspection Checklist, resulting in fatigue failure of the bolts.

Full narrative available

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