Incident Overview
A pilot was flying a helicopter for approximately 25 minutes when he observed fluctuations in the oil pressure and torque gauges. In response, he initiated an approach to a precautionary landing spot on an asphalt pad. At about 150 feet above ground level, the engine ceased operation. The pilot performed an autorotation to touch down on a paved road. During the landing, the main rotor blades severed the tail boom aft of the horizontal stabilizer.
Maintenance History
The engine had undergone maintenance and had been reinstalled in the helicopter the night before the accident. Following the reinstallation, the pilot conducted a test run and leak check of the engine, noting no discrepancies. The pilot reported that the engine had been running normally until the gauge fluctuations occurred.
Post-Accident Examination
An examination of the engine revealed that the oil output line was connected but loose, and oil was observed dripping from the fitting area. Oil was found over most of the fuselage and underneath the engine. Approximately 1 pint of oil remained in the oil sump. Further teardown of the engine disclosed that the number 8 bearing was destroyed and no oil was present throughout the lubrication system.
Maintenance Manual Specifications
The Bell Helicopter maintenance manual specifies a torque value for the fitting on the oil output line. 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 access it and was in a hurry.