Incident Overview
A helicopter conducting firefighting operations under contract experienced a loss of hydraulic control while en route to a fire drop location. The aircraft was equipped with a Bambi waterbucket attached to a cargo hook. The pilot had just filled the bucket from a pond and was heading to drop water on a designated part of a nearby fireline.
Sequence of Events
During the flight, the pilot noted the illumination of the master caution light and one caution segment light. The pilot then made a turn to initiate an autorotation toward a clear-cut area. However, due to low rotor rpm, the helicopter made a hard landing with substantial downward velocity and some forward speed. Upon impact, the landing skids collapsed, and the helicopter rolled to the right. The main rotor blades contacted the ground. The engine remained running at idle power until the fuel lines were depleted of fuel.
Postcrash Examination
After the accident, investigators examined the flight controls, hydraulic system, electrical system, fuel system, tailrotor system, and transmission. Additionally, the hydraulic servo actuators, hydraulic pump, fuel control, and power turbine governor were checked and bench tested. During this postcrash examination, no preimpact mechanical failure or malfunction was found.