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The pilot had been flying for about 25 minutes when he noticed that the oil pressure gauge and torque gauge were fluctuating. He initiated an appraoch to a precautionary landing spot on an asphalt pad. About 150 feet AGL, the engine quit and the pilot autorotated to touch down on a paved road. The main rotor blades severed the tail boom all of the horizontal stabilizer. The engine had received some maintenance work and had been reinstalled in the helicopter the night before the accident, at which time the pilot performed a test run and leak check of the the engine, with no noted discrepancies, the pilot further stated that the engine had been running normally until the fluctuation of the oil pressure and torque gauges. During an examination of the engine, the oil output line was connected, but loose, and oil was seen dripping from the fitting area. Oil was observed over most of the fuselage and underneath the engine. There was approximately 1 pint of oil found in the sump. Further teardown of the engine revealed that the number 8 bearing was destroyed and no oil was found throughout the lubrication system. The Bell helicopter maintenance manual specifies a torque value for the fitting on the oil output line, however, the mechanic who installed the engine reported that he did not use a torque wrench to tighten the line because he would have had to remove some other lines to get to it and he was in a hurry. (-23) on August 4, 1998 at 0745 hours pacific daylight time a Bell 206B, N5016G, experienced a loss of engine power near Lucerne Valley, California. The aircraft sustained substantial damage in the forced landing. No injuries were reported by the sole occupant, who holds a commercial pilot certificate. The pilot stated that he was at cruise with power setting between 75-80% of torque. All engine instruments were indicating normal readings when engine oil pressure began fluctuating between 20-100 PSI, followed by torque fluctuations between 20-80%. The pilot began descent to land and on short final engine failed causing an auto-rotation to available area resulting in main rotor striking tail boom. The tail boom and tail rotor was completely severed from the helicopter. Engine tear down revealed the following cause for engine failure. On September 4, 1998, I was contacted by investigator noe loni mars at the national transportation safety board who observed the engine tear down. The oil output lines were found loose causing the running turbine engine to deplenish itself of oil. The #8 engine bearing became destroyed due to lack of lubrication that subsequently caused the sudden stoppage of the engine. This engine failure occurred less than 24 hours of engine installation.