Accident Sequence
A 450-hour commercial helicopter pilot departed approximately 0615 on the return leg of a personal cross-country flight. Around 0805, two witnesses observed the helicopter following a road. The first witness reported seeing the helicopter following a highway northbound at a "normal" height, then noted that it "lost altitude very quickly." The second witness, traveling southbound, saw the helicopter low over the median, heading north at an estimated height of 20 to 30 feet—"lower than tree line." This witness also stated that the pilot was "concentrating on the center gauges, console, and was working the controls fast and vigorous."
Damage Examination
Both an FAA inspector and a Department of Public Safety trooper noted that the helicopter impacted power lines before hitting the ground. The top and forward sections of the left and right landing skids showed evidence of a wire strike. The fuel tank was breached near the top, though approximately 3 quarts of fuel was drained through the gascolator. The main rotor blades lacked leading-edge gouges; one blade was bent upward, while the other two were bent downward, with one showing scuff and paint marks consistent with contact with the tail rotor boom. That blade also had slight buckling on the trailing edge. The main rotor drive shaft and housing were broken from the transmission; the shaft was bent about 45 degrees with no twisting motion. The tail rotor drive shaft was separated in two, also without twisting, and had longitudinal scuff and paint transfer marks. The tail rotor blades had numerous impact marks on their sides, removing paint and leaving small dents, but no leading-edge gouges.
Mechanical Findings
Control continuity through the cyclic and collective was established, but three bolts connecting the cyclic controls were missing safety cotter pins. One castled nut had backed off to within a few threads of falling off. The mixture control cable clamp on the fuel servo was metal with no rubber cushion, and it had no holding effect on the cable, which was free to move. The bottom set of spark plugs were examined: all four were worn out—ranging from normal to severe—and lead fouled.
Post-Accident Engine Run
A post-accident engine run was conducted. The engine started and operated through the normal rpm range with no abnormalities. After shutdown, fuel leaked through the servo and out the induction system when the mixture was left in the full-rich position.
Conclusion
The reason for the loss of engine power could not be determined.