Bell 222U N222UT accident near Santa Maria, California

Probable cause

The pilot's inadequate preflight inspection to ensure that all tie-down straps were removed prior to flight. Contributing to the accident was the pilot's improper management of sleep opportunities during the preceding rest period, which likely contributed to the development of fatigue.

NTSB analysis

On April 5, the pilot reported for work at 0730 to begin a daytime work shift. He was off duty on April 6 and 7, and on the 7th he went to bed at midnight. In the morning, he awoke at 0800. According to the pilot, he was aware that on the 8th he was scheduled to work a nighttime shift, but he remained awake all day. He reported for work at 1930 to begin his nighttime shift. During his preflight inspection at the beginning of his shift, he noted that both the tail rotor and a main rotor blade were tied down. He stated that he went to sleep at 2300 after being awake for 15 hours. On April 9, after sleeping about 2 hours, he received a duty call about 0110 and was dispatched for the accident flight. During a walk-around inspection in the dark, he observed a flight nurse proceed to the opposite side of the helicopter. According to the pilot, he assumed that the flight nurse had untied the tail rotor tie-down strap. He only removed the main rotor blade's tie-down strap. The pilot's failure to ensure that the tail rotor blade's tie down was removed was an error of omission, indicative of fatigue impairment. During the engine start operation, the tail rotor's strap broke. This resulted in damage to a tail rotor blade and all of the pitch change links. The pilot was unaware of this event, and he flew to the designated hospital to pick up a patient. With the patient on board during the subsequent engine start operation, a flight nurse observed broken tie-down strap material wrapped around the tail rotor driveshaft. The pilot shut down the engine. With the assistance of the flight nurse, the pilot removed the tie-down material. He then flew the patient on the prescribed emergency medical services flight and landed uneventfully at the next hospital. Thereafter, the pilot reinspected the helicopter and observed that it was damaged. The company's director of maintenance inspected the helicopter and found it unairworthy. The damaged tail rotor blade and pitch change links were unserviceable and were discarded. The blade was observed to be scratched, and it had voids in its composite material structure. The pitch change links were bent and their bearings were seized, compromising the flight control system.

Text from the NTSB. Open the NTSB docket for WPR10LA200 for the full record.