Enstrom F-28C N574H accident near Abilene, Texas

Probable cause

The flight instructor's failure to conduct an autorotation following the loss of engine power due to fuel exhaustion. Contributing to the accident was the failure of the flight instructor and the student pilot to visually check fuel levels to ensure adequate fuel on board for the planned flight.

NTSB analysis

A student pilot and flight instructor departed with full fuel tanks on a round-robin cross-country flight in the student pilot's helicopter. The first three legs were uneventful with landings at all three locations. The flight instructor and the student pilot did not visually check the fuel tanks at stops during the flight. On the last leg, the instructor noted the fuel gauges and made the decision to continue to the destination. The student pilot told the flight instructor that the fuel quantity on board the helicopter was low. The flight instructor informed him that the fuel gauges were often faulty and that they had enough fuel to complete the return leg of the flight. About 2 miles from the destination, the helicopter yawed left twice, and the engine and rotor rpm began to decay. The instructor lowered the collective and leveled the helicopter. The rotor rpm decayed even further, to the point that it was below the minimum for autorotative descent. The instructor pushed the nose over then brought the helicopter back to a level attitude. He reported that this caused the blades to cone upward and increased the rotor rpm, but the rpm was still below the red line. The instructor nosed the helicopter over again and turned left but was unable to regain rotor speed. The instructor was certain that, in addition to the loss of engine power, the overrunning clutch had not disengaged the engine from the transmission. The instructor leveled the helicopter about 3 feet above the ground and applied collective but reported that only about one-third of normal rotor rpm was available. The helicopter landed hard and the main rotor blades impacted the tailboom. A postaccident examination revealed that the fuel tanks contained no usable fuel, and, when serviced with fuel, the engine was operational. An examination of the overrunning clutch operation revealed no anomalies.

Text from the NTSB. Open the NTSB docket for CEN13LA099 for the full record.