What happened
The aircraft departed the right side of runway 7 while performing the landing roll. The pilot reported that the aircraft veered sharply to the right during this phase of flight. A single rubber skid mark, approximately 150 feet in length, was located on the runway surface at the point of departure.
Weather conditions were noted by another pilot as having a tailwind component down the runway with speeds between 10 and 15 knots.
The investigation
A mechanical examination of the aircraft revealed that the left brake master cylinder had failed. Analysis of the brake fluid showed contamination from metal particles. A visual inspection of the cylinder walls indicated signs of significant deterioration.
Findings
The failure of the left brake master cylinder prevented effective braking on the left side, contributing to the loss of directional control. The presence of metal particles in the fluid and the deteriorated condition of the cylinder walls were identified as the mechanical causes of the failure.