What happened
During a CFR Part 135 on-demand charter operation, a crew was completing the final leg of a multi-destination flight. The flight had originated approximately 16 hours prior to the event. During the approach, the crew encountered unexpected headwinds, leading the first officer to express concerns regarding fuel reserves. Upon approaching the destination, the captain notified the air traffic control specialist of the low fuel state, resulting in a priority landing clearance.
As the crew attempted to configure the aircraft type for landing, they found the flaps would not extend past 8 degrees. Following the extension of the landing gear, the captain identified a total loss of hydraulic pressure, noting that the gear doors remained stuck in the down position. The crew prepared for a landing with limited braking capability. The aircraft type touched down mid-way down the 6-foot runway and failed to stop within the paved surface. The aircraft overran the runway, crossed a road, and collided with a building.
There were 0 fatalities and 0 injuries reported in the immediate sequence, though the aircraft sustained significant damage. During the landing roll, the crew was unable to deploy the emergency drag chute, and the nitrogen-charged emergency brake system was not utilized.
Findings
An investigation into the hydraulic system revealed that the hydraulic pressure relief valve and the hydraulic pressure regulator assembly showed physical damage, including indentations and gouges consistent with being struck by a tool. Testing confirmed that the hydraulic pressure relief valve piston was stuck in the open position, which caused the loss of system pressure. While the emergency drag chute system was found to be mechanically functional, the crew was unable to deploy it during the excursion.