Pilot Debrief

POOL MURPHY MOOSE near Steamboat Springs, CO — 2012-05-12

Final reportCEN12LA298
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Date
2012-05-12
Location
Steamboat Springs, CO, USA
Airport
KSBS
Aircraft
POOL MURPHY MOOSE
Registration
N223DH
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Landing

Probable cause

A locked left brake for reasons that could not be determined because independent observations of the postaccident condition of the airplane could not be performed, and the pilot’s subsequent loss of control.

NTSB narrative

The pilot reported that during the landing roll in the experimental kit-built airplane, the left wheel brake locked, and the airplane departed the left side of the runway. The left landing gear dug into the soft dirt and the airplane nosed over. The pilot/owner/builder disassembled both brake master cylinders and the parking brake valve without federal oversight and found no foreign material or operating problems with the master cylinder or parking valve. The variance of 0.009 inches in the dowel pin length documented by the pilot/owner/builder was explained by standard manufacturing procedures used to achieve near simultaneous operation of the valve between the left and right sides of the parking brake. Functional testing of the parking brake valve revealed no anomalies. Due to the disassembly of the parking brake valve and parking brake assembly without federal oversight, investigators were unable to determine their condition on the airplane at the time of the accident. Accordingly, the cause of the locked left brake could not be determined.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have inspected brake system before flight to ensure proper function.

NTSB coding

Evidence available

  • 5 docket documents
View NTSB final reportView NTSB docket

Docket documents5

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