What happened
During the landing phase of the flight, the aircraft completed a standard touchdown on the runway. Immediately following the landing, the pilot experienced a total loss of braking pressure on the left side, noting that the brake pedal moved all the way to the floor without providing any resistance. In an effort to keep the aircraft on the runway, the pilot attempted to maintain directional control, but the plane drifted toward the right edge of the runway and exited the paved surface into the adjacent grass area.
As the aircraft moved into the grass, the landing gear collapsed. The sequence of events resulted in the aircraft coming to a halt after sustaining significant structural damage, specifically to the left wing spar. There were no reported injuries or fatalities during the incident.
Findings
An investigation into the mechanical failure revealed that the left brake was non-functional at the time of the incident. Post-accident inspections identified a small leak of hydraulic fluid located at the shaft of the parking brake valve, which is situated within the pressurized section of the cabin. It was determined that air entered the brake line through this leak while the cabin was under pressure, which subsequently prevented the left brake from operating correctly.