Pilot Debrief

MITSUBISHI MU-2B-20 near Walterboro, SC — 2011-01-16

Final reportERA11IA172
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Date
2011-01-16
Location
Walterboro, SC, USA
Airport
RBW
Aircraft
MITSUBISHI MU-2B-20
Registration
N52CD
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Landing

Probable cause

The inadequate inspection and rigging of the nose landing gear downlock mechanism by maintenance personnel, which resulted in the failure of a bolt and the subsequent collapse of the nose gear during the landing roll.

NTSB narrative

The pilot reported hearing a “pop” sound from the nose gear area when the gear was extended for the landing. Toward the end of the landing roll, the nose gear collapsed. A postaccident examination of the nose gear revealed that the bolt that holds the downlock drag brace joint link to the airframe structure had fractured. A metallurgical examination revealed that the bolt failed in reverse bending fatigue, which is associated with the bolt having insufficient clamping pressure (looseness). The airplane’s last required inspection was about 70 flight hours and 40 gear cycles before the nose gear collapsing, and the nose gear downlock system rigging should have been inspected at that time.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Inspection of the nose gear down lock mechanism for proper rigging could have prevented failure.

NTSB coding

  • Landing gear collapse · Landing-landing roll
  • Maintenance

Evidence available

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

Docket documents10

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