Accident Narrative
On July 2, 2009, at approximately 1515 mountain daylight time, a Bell 206L-1 helicopter (registration N38AZ) operated by Mile High Helicopters Incorporated was substantially damaged during a hard landing near Breckenridge, Colorado. The flight was conducted under Title 14 Code of Federal Regulations Part 133 as an external load operation without a flight plan. Visual meteorological conditions prevailed at the time.
The helicopter was expecting to move an external load weighing 300 pounds, suspended by a 50-foot synthetic cable with a remote hook attachment to the cargo hook. Release functions were verified before the flight. The helicopter transported the external load to a landing zone at a higher elevation. According to the operator, the pilot made a shallow approach to the upper landing zone when the helicopter began an uncommanded rotation to the right. The pilot applied full left anti-torque pedal and released the external load, but the helicopter could not be recovered before landing hard on a sloping boulder field. The helicopter rolled and came to rest on its right side.
Injuries and Damage
The commercial pilot sustained serious injuries. One person on the ground sustained minor injuries during the roll-over. The helicopter sustained substantial damage to the left, right, and aft sides of the fuselage. The tailrotor section was damaged, and evidence of rotation throughout the tailrotor drive shaft was observed.
Meteorological Conditions
A meteorological study of the accident site, located at 12,925 feet mean sea level, indicated the presence of convective echoes to the southwest and north, capable of producing gusting winds up to 30 knots. The temperature was between 50 and 52 degrees Fahrenheit, with a relative humidity of 50 percent. The density altitude was calculated to be between 14,500 and 14,700 feet.
Performance Considerations
The helicopter was equipped with a Rolls-Royce 250-C30P engine, described in technical manuals as providing "206L3 performance for 206L1 helicopters." All performance calculations used Bell 206L3 charts. Using an estimated total gross weight of 3,600 pounds (3,000 pounds for the helicopter plus internal load and 600 pounds for the external load), the helicopter would have been operating in the Area B section of the Out of Ground Effect (OGE) Hover Ceiling chart. This area is subject to the Critical Relative Wind Azimuth chart, which lists a wind avoid area between 050-210°. The manual states that "tail rotor control margin...may preclude operation in Area B of the hover ceiling charts when the relative wind is in the CRITICAL WIND AZIMUTH AREA." With the environmental conditions at the time of the accident, the Area B portion of the OGE Hover Ceiling chart was applicable down to a gross weight of 3,300 pounds. The helicopter would have still been operating in Area B even with the originally intended 300-pound external load. During wreckage recovery by a K-Max helicopter, the external load was estimated to weigh approximately 600 pounds, 300 pounds more than expected by the pilot.