Monticello, UT, USA
N20840
Aerospatiale AS-350BA
According to the pilot, he had moved approximately 80 bags of seismic sensor cable earlier that morning with no problems. At approximately 1120, the pilot stopped operations to change lines. He proceeded to pick up five bags and was en route to the drop off point. During the approach to the north, the pilot "noticed that the Nr (rotor rpm) was high at roughly 400 rpm as [he] turned to the west." As the pilot slowed down, he added collective to reduce the rotor speed. The rotor rpm began to slow, at which point the pilot lowered the collective and applied forward cyclic to maintain forward airspeed. The rotor speed continued to decrease and the "low rotor speed warning horn" sounded. The pilot lowered the collective and flared, at which point the bags contacted the ground. The pilot then "noticed that the Nr was low" at approximately 320 rpm. The pilot "zeroed the airspeed, pumped the collective once[,] trying to slow the rate of decent and pulled up on the collective," just before impacting the ground. The helicopter settled onto the load beneath it, and subsequently rolled over on its right side causing substantial damage. An examination of the helicopter revealed no anomalies.
On December 2, 2002, at approximately 1125 mountain standard time, an Aerospatiale AS-350BA, N20840, operated by Crew Concepts Inc., was substantially damaged following an autorotation and subsequent landing rollover 1 mile east of Monticello, Utah. The commercial pilot, the sole occupant on board, received minor injuries. The external load operation was being conducted under the provisions of Title 14 CFR Part 133. Visual meteorological conditions prevailed and no flight plan had been filed for the local geophysical flight that originated approximately 5 minutes prior to the accident. According to the pilot, he had moved approximately 80 bags earlier that morning with no problems. The bags contained seismic sensor cables. At approximately 1120, the pilot stopped operations to change lines. He proceeded to pick up five bags and was en route to the drop off point. During the approach to the north, the pilot "noticed that the Nr [rotor rpm] was high at roughly 400 rpm as [he] turned to the west." As the forward speed slowed down, the pilot added collective to reduce the rotor speed. The rotor rpm began to slow but continued to decrease, at which point the pilot lowered the collective and applied forward cyclic to maintain forward airspeed. The rotor speed continued to decrease and the "low rotor speed warning horn" sounded. The pilot lowered the collective and flared, at which point the bags contacted the ground. The pilot then "noticed that the Nr was low" at approximately 320 rpm. Impact with the ground was unavoidable and the pilot "zeroed the airspeed, pumped the collective once[,] trying to slow the rate of decent and pulled up on the collective," just before impacting the ground. The helicopter settled onto the load on the ground. Subsequently, the helicopter rolled over, coming to rest on its right side. The tail boom was severed, the engine and transmission were separated, and the main rotor blades and hub assembly were destroyed. On March 6, 2003, the fuel control unit was examined at Turbomeca, Grand Prairie, Texas. No anomalies were reported. An examination of the helicopter's systems revealed no anomalies. The calculated density altitude at the accident site was 7,443 feet. The helicopter's maximum substantiated pressure altitude is 16,000 feet.
the pilot's failure to maintain rotor rpm. A related factor was the presence of an object in the path during the touchdown.
Source: NTSB Aviation Accident Database
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