Pilot Debrief

STINSON 108-3 near El Monte, CA — 2020-11-03

Final reportWPR21LA064
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Date
2020-11-03
Location
El Monte, CA, USA
Airport
EMT
Aircraft
STINSON 108-3
Registration
N6855M
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Landing

Probable cause

A loss of directional control during the landing roll due to an undetermined failure of the tailwheel assembly.

NTSB narrative

During an instructional flight in the tailwheel-equipped airplane, the airplane veered left. Despite the instructor’s application of corrective control inputs, the airplane did not respond as expected, ultimately resulting in a ground loop and substantial damage to the left wing. Postaccident examination revealed that both of the airplane’s tailwheel steering springs and tension chains were missing. The springs were found on the runway following the accident, separated from each other by about 1,700 ft. Neither of the chains were located. The manufacturer’s instructions called for the spring to connect directly to the tailwheel yoke, and the chain to connect to the steering arm with a connector clip. Evidence suggests that the spring was instead incorrectly connected directly to the steering arm. This reverse installation, while not in compliance with the maintenance instructions, did not appear to functionally affect the operation of the steering system, and therefore without examination of the missing chains or further examination of the tailwheel assembly, the significance of this finding could not be determined.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Proper maintenance of tailwheel assembly could have prevented failure.

NTSB coding

Evidence available

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

Docket documents5

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