ATL85FA193

The plt took off at 1805 with 150 lbs of fuel remaining, intending to fly to beckley, WV to refuel. He stated that afterhe was in lvl flt at about 3000 ft MSL for 3 to 4 min, he noted an unusual jerk or vibration in the rear. Suspecting a psbl tail rotor problem, he lowered the collective & turned toward an open area. He then noted that the eng had lost power. Drg an autorotative landing, the helicopter touched down hard without enough RPM to cushion the lndg. An exam of the fuel sys revealed there was about 20 gal of fuel remaining. The eng & fuel pumps operated normally when tested. However, further checks revealed that when fuel in the aft tank was below the stand pipe, fuel would leak to the front tank; also, there was virtually no induced flow in the left transfer sys. Disassembly revealed the standpipe in the aft tank was not properly aligned, thus the o-ring was not properly seated, which allowed a leak. A piece of masking tape was fnd in the inlet to the left transfer pump. As the front tank apchd empty (drg opn) air was entrained in the fuel.