Accident Summary
During landing, the aircraft experienced a left brake failure while the pilot was applying hard brake intermittent applications. The failure caused the aircraft to swerve to the right and depart the runway, subsequently colliding with trees approximately 50 feet off the right side of the runway.
Sequence of Events
According to the investigation, the left brake failed during hard brake applications. The pilot then failed to release the right brake in a timely manner, causing the aircraft to swerve to the right and exit the runway onto wet, soft terrain. While sliding, the pilot applied full power in an attempt to fly over small trees in the path. However, realizing there was insufficient room, the pilot reduced power just prior to impacting the trees.
Mechanical Findings
Post-accident examination by the operator revealed that a neoprene O-ring on the left brake was split, resulting in loss of brake fluid and brake failure. Further inspection found that one of the left brake pucks was excessively worn. It was determined that hard brake application forced the O-ring out of place due to the worn puck, and subsequent brake applications caused the O-ring to be pinched, leading to fluid loss.