On September 19, 1985, a Cessna 425 (registration N1222B) was involved in an aviation accident near Boulder, CO. Investigators recorded the probable cause as: The pilot's failure to maintain directional control and his incorrect feathering of both propellers, which were preceded by a brake system malfunction due to a missing brake puck. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot experienced left brake failure during landing roll, compounded by an erroneous feathering of both propellers, causing the aircraft to leave the runway and strike a fence.
What happened
The pilot reported conducting a normal landing approach. During the rollout phase on the runway, the left brake pedal failed to respond to application. In response to this malfunction, the pilot incorrectly feathered both propellers. The loss of braking capability combined with the propeller configuration caused the aircraft to depart the end of the runway and strike a fence.
The investigation
A post-accident examination of the aircraft brake system revealed that a brake puck was missing from the assembly. This mechanical deficiency would have resulted in poor braking action, contributing significantly to the inability to stop the aircraft within the available runway distance.
Probable cause
The pilot's failure to maintain directional control and his incorrect feathering of both propellers, which were preceded by a brake system malfunction due to a missing brake puck.