Amateur-built MURPHY MOOSE N223DH accident near Steamboat Springs, Colorado

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 analysis

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.

Text from the NTSB. Open the NTSB docket for CEN12LA298 for the full record.