What happened
During a scheduled maintenance test flight, the pilot was required to shut down the left engine following a malfunction involving the left propeller. The flight was conducted as a single-engine instrument landing system (ILS) approach toward runway 13. As the aircraft reached the short final phase of the approach, the crew observed that the alternator light had illuminated and the hydraulic pressure gauge was reading zero.
Because the landing gear had already been deployed and the flaps were in a partially extended position, the crew decided to proceed with the landing. Once the aircraft reached the runway, the pilot attempted to activate the direct current (DC) hydraulic pump. However, the aircraft could not be kept on the centerline due to the absence of nose wheel steering and a lack of effective braking capability. The aircraft veered toward the right side of the runway and exited the paved surface. The movement continued until the aircraft struck the airport perimeter fence and came to a rest in a drainage ditch.
Findings
Post-incident examination of the aircraft indicated that the hydraulic pump switch had not been successfully engaged. The loss of hydraulic pressure resulted in the failure of critical flight systems, specifically the nose wheel steering and the braking system, leading to the loss of directional control during the landing roll.