Pilot Debrief

SCHWEIZER AIRCRAFT CORP G-164B near Clarksdale, MS — 2008-08-26

Final reportMIA08LA174
Sign in to save
Date
2008-08-26
Location
Clarksdale, MS, USA
Airport
CKM
Aircraft
SCHWEIZER AIRCRAFT CORP G-164B
Registration
N3633S
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Taxi

Probable cause

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.

NTSB narrative

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.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Not torque checking the axle attachment bolts during the last inspection.

NTSB coding

Evidence available

  • 9 docket documents
View NTSB final reportView NTSB docket

Docket documents9

Related mishaps