Pilot Debrief

CESSNA 172C near Williamson, GA — 2015-03-15

Final reportERA15LA160
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Date
2015-03-15
Location
Williamson, GA, USA
Airport
GA2
Aircraft
CESSNA 172C
Registration
N8452X
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Landing

Probable cause

The separation of the nosewheel upon landing due to a missing bolt that attached the upper torque assembly to the nosewheel steering arm assembly. When and how the bolt separated could not be determined.

NTSB narrative

The pilot made a soft-field landing to a grass runway, and the initial touchdown was on the main wheels with the airplane in a nose-up attitude. As the airplane decelerated, the pilot lowered the nosewheel and felt a "significant" shimmy after it touched down. The pilot thought the shimmy damper had failed, so he applied back pressure on the control wheel to minimize weight on the nosewheel. As the airplane continued to decelerate, the pilot again lowered the nose, and a more substantial vibration occurred. He then raised the nosewheel as much as possible. Eventually, so much groundspeed had depleted that he could no longer hold the airplane's nosewheel off the ground. When the nosewheel touched down again, it separated from the airplane. Examination of the airplane revealed that a bolt and associated washer and nut that attached the upper torque assembly to the nosewheel steering arm assembly was missing, and it was not located. The pilot said that he saw the bolt during his preflight inspection. It could not be determined when the bolt separated from the nosewheel. According to the airplane manufacturer, without that bolt, the lower shock strut assembly of the nosewheel would freely caster in the shock strut tube assembly, which would result in a significant shimmy, and the nosewheel steering control would be significantly reduced or nonexistent. Without the torque assembly attached, the shimmy dampener would have limited-to-no effect. A review of the airplane maintenance logbooks revealed that no recent maintenance had been conducted on the nosewheel. The fracture surfaces of the broken nosewheel assembly were consistent with having failed due to overload forces during landing, and no preimpact anomalies were noted. It could not be determined how the bolt separated from the nosewheel steering arm assembly.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have checked for missing bolt during preflight inspection.

NTSB coding

Evidence available

  • Photos
  • 7 docket documents
View NTSB final reportView NTSB docket

Docket documents7

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