Bell 206L-1 LongRanger, Peach Springs, Ariz., May 2, 2005–The NTSB was unable to determine the reason for the loss of power that caused the LongRanger to crash during a long-line sling load operation. The helicopter was carrying fuel cans in a net from a landing strip on the rim of the Grand Canyon to the canyon floor to refuel tour boats on the Colorado River.
The commercial pilot, the sole occupant, said he was descending at about 50 fpm as he neared the ground. The wind conditions were calm, or nearly so. With his head outside the cockpit watching the ground crew, he heard a tone, and then heard a series of three low-frequency popping noises. He was unsure if the popping sounds were coming from the engine or from the main rotor blades. The helicopter then began to settle toward the ground and descended to a hard impact into desert scrub brush. After hearing the popping noises, the pilot rolled off the power and entered an autorotation.
Witnesses to the accident told investigators that the helicopter’s approach was a controlled approach, and there was no sway or other unusual movement in the load.
The Rolls-Royce 250-C30P engine was shipped to a repair facility with a test cell, where no significant irregularities were noted. Both the power-turbine governor and gas-producer fuel control were tested at the manufacturer’s facilities, and no conditions that would have prevented normal operation of either unit were identified.
The helicopter, registered to Monarch Enterprises of Kirkland, Wash., was substantially damaged and the pilot was uninjured.