Aerospatiale AS 355F1 N548SA accident near Temple Bar, Arizona

Probable cause

The pilot’s inadequate preflight inspection. Contributing to the accident was the pilot’s diverted attention during the preflight inspection.

NTSB analysis

The pilot reported that after arriving to work late he began his preflight inspection on the helicopter. As the pilot was inspecting the left engine, the refueling truck arrived and the pilot lowered the left engine cowling door and tended to the refueling of the helicopter. The pilot said that following the refueling of the helicopter, he continued his preflight inspection and subsequently boarded the passengers “not realizing I left the engine cowling ‘unlatched’.” While en route to the flight’s intended destination, the pilot heard a “pop” followed by feedback in the cyclic control. The pilot was informed by the pilot of a second helicopter that the left engine cowling appeared to be open and partially separated. The pilot initiated a precautionary landing to the desert surface and landed without further incident. Examination of the helicopter by a Federal Aviation Administration inspector revealed that two of the three main rotor blades were damaged. One main rotor blade exhibited a one-inch-long gouge about one-quarter of an inch in depth near the blade root. A portion of the left engine cowling was separated and not located.

Text from the NTSB. Open the NTSB docket for WPR10LA075 for the full record.