What happened
During the landing phase on Runway 33, the pilot of the aircraft experienced a malfunction involving the right-side low pitch stop propeller system. Upon seeing the system annunciator light illuminate while on the base leg, the pilot followed the pilot operating handbook procedures by pulling the circuit breaker and leaving it out.
As the aircraft continued its landing roll, a severe yaw toward the right side occurred. In an attempt to maintain the centerline, the pilot increased power to the right engine to realign the aircraft. Despite applying brakes and reverse thrust, the pilot noted a lack of effective braking action, followed by an uneven braking sensation where the right side appeared to grip while the left did not.
This imbalance, caused by the combination of the propeller system malfunction and asymmetrical braking, created significant adverse yaw. The pilot attempted to straighten the aircraft by applying power again and initially decided to execute a go-around. However, the aircraft lacked the necessary airspeed and remaining runway length to safely complete the maneuver. Upon re-applying the brakes, the aircraft experienced another sharp yaw to the right. The aircraft eventually left the paved surface at the edge of the runway and entered the grass, where the pilot managed to bring the plane to a stop.
Findings
An investigation into the braking system revealed that both the left and right main landing gear hydraulic brake hoses showed signs of damage caused by a hand tool.