20100407005019A

N118NR was on a local VFR flight, departing pym at approximately 1500L and proceeded to the vicinity of the tan airport at wich time the PIC decided to return to pym. After flying a total of approximately 50 minutes the PIC observed abnormally high coolant tempature and elected to execute a precautionary landing. As he was circling the landing zone he experienced a loss/reduction in power. The aircraft landed hard with a tailwind. Upon landing the right hand skid collapsed, the main rotor struck the tail boom approximately two thirds of the lenth of it towards the tail rotor. The aircraft rotated approximatel 180 degrees comming to a rest on the right side. The tail rotor and last one third of the tailboom seperated from the aircraft. The tail rotor was intact. Investigation revield that there was approximately 4 or 5 gallons of fuel remaing in the fuel tank. The engine was intact and inspectors were able to rotate the engine crank shaft manually. Corrosion was found on the cooling fins of the radiator. The quanity of engine coolant was not able to be determined at the accident scene due to the position of the aircraft. Subsequent inspection of the aircraft revield that a coolant hose leading from the coolant expansion tank to the engine cooling system was detached. A radiator hose clamp was attached to the hose and appeared to be in a position consistant with it being secured. Inspectors were unable to determin if the hose was attached at the time of the accident or wether it beacame detached due to the crash forces or due to moving the aircraft. The engine coolant intake fitting to the waterpump was removed. There were no visible signs of coolant in the engine block at the water pump inlet although there were signs of liquid coolant residue found. There were no indication of coolant residue on the aircraft that would be indicutive of a coolant hose becomming detached in flight. The engine crankshaft was rotated and the water pump impeller rotated as one would expect.