What happened
During the takeoff roll, the pilot reported that the aircraft began to track to the right. In an attempt to realign the aircraft with the runway centerline, differential braking input was applied. However, when the brakes were subsequently applied to stop the aircraft, they failed to function. As a result, the aircraft veered off the left side of the runway and entered a ditch.
The investigation
An examination of the wheel brakes revealed that the hydraulic pucks were leaking. Additionally, the brake disc and linings were found to be worn. Further inspection of the accumulator showed a ruptured diaphragm, which prevented the system from maintaining necessary pressure. No other mechanical or flight control issues were reported.