Pilot Debrief

HAWKER BEECHCRAFT G58 near Medford, OR — 2012-07-20

Final reportWPR12LA324
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Date
2012-07-20
Location
Medford, OR, USA
Airport
MFR
Aircraft
HAWKER BEECHCRAFT G58
Registration
N7122T
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Landing

Probable cause

A loss of directional control on landing for reasons that could not be determined based on the available evidence.

NTSB narrative

The owner/pilot reported that all aspects of the personal cross-country flight were uneventful until touchdown when the airplane immediately experienced directional control issues. The airplane subsequently veered off the right side of the runway and struck a sign and a ditch before it came to rest. All three landing gear were fracture-separated from the airplane during the accident sequence. The right and left main landing gear torque links exhibited different damage patterns. None of the attachment hardware for the left torque link knee joint was located. The lack of any landing gear operating anomalies during the accident flight's taxi, takeoff, gear retraction, and gear extension sequences, combined with the damage patterns to the left main landing gear torque links, were consistent with the knee joint attachment bolt being present through at least the beginning of the failure sequence on landing and with the bolt being at least partially installed during the landing. Further, the available evidence did not indicate that a pre-existing mechanical failure of the knee joint bolt had occurred. For the bolt to partially back out of its proper position, the retaining nut would have to be missing either due to the cotter key being lost as a result of mechanical failure or absent because it was never installed. If the cotter key was damaged or the nut was improperly torqued, it is possible that multiple taxi, takeoff, and landing cycles could have damaged and eventually caused the cotter key, the nut, or the bolt to fail, but no evidence was found to support that scenario. The two mechanics who repaired the left main landing gear strut 7 months before the accident reported that the cotter key was installed during the repair. Although the pilot asserted that the cotter key was never installed, he and another pilot had completed 32 flights, not including the accident flight, in the airplane since that time, thus, providing 33 opportunities to detect its absence during their respective preflight inspections, yet neither did so. In addition, those flights were accomplished after renewed attention to the left main landing gear because of the strut repair; however, neither pilot noted any missing hardware. Based on the available evidence, which did not include the attachment hardware, the underlying reason for the loss of directional control could not be determined.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have ensured cotter key was installed during maintenance.

NTSB coding

Evidence available

  • 23 docket documents
View NTSB final reportView NTSB docket

Docket documents23

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