Pilot Debrief

AIR TRACTOR INC AT-502 near Forrest City, AR — 2013-02-07

Final reportCEN13LA168
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Date
2013-02-07
Location
Forrest City, AR, USA
Aircraft
AIR TRACTOR INC AT-502
Registration
N198LA
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Climb

Probable cause

The in-flight separation of the left aileron's push-pull rod and hardware. Contributing to the accident was the failure of maintenance personnel to apply proper torque to the self-locking nuts.

NTSB narrative

After making an agricultural application, the pilot made a climbing left turn; the airplane then began vibrating and shaking. The pilot was able to return the airplane to level flight, but it rocked left and right, with the left aileron going up and down from stop to stop. The pilot chose to perform an emergency landing in a field next to an airport. A postaccident examination of the airplane revealed that the two aileron push-pull rod bolts were missing. The bolts and associated hardware were not located among the wreckage. The airplane had undergone extensive maintenance about 5 months before the accident. A review of the airplane's maintenance manual revealed that the nuts installed in the airplane control system are self-locking nuts, which can loosen if insufficient torque is applied to them. It is likely that maintenance personnel applied improper torque to the aileron's push-pull rod self-locking nuts, which resulted in the eventual loosening of the nuts and the separation of the left aileron's push-pull rod and hardware.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have aborted the climb after initial vibrations were felt.

NTSB coding

Evidence available

  • 4 docket documents
View NTSB final reportView NTSB docket

Docket documents4

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