Incident Summary
A pilot reported that during the landing roll, the left brake was inoperative. Upon realizing the problem, there was insufficient runway remaining to stop or execute a go-around. At the end of the runway, there was a deep drop-off, so the pilot used the right brake. As a result, the aircraft departed the right side of the runway. The right landing gear separated when the aircraft entered soft terrain and a depression beside the runway.
Examination Findings
An examination of the left brake system revealed that the master cylinder, a Paramount Model VI-15-750-3, was wet with hydraulic fluid. The cylinder was disassembled, and inspection of the master cylinder piston shaft showed several compression indentations. These indentations were located in a manner that permitted fluid leakage and introduction of air into the cylinder. The cause of the indentations was not determined.