Incident Overview
A pilot for an on-demand helicopter company was preparing to depart from a remote biological survey site. The flight was being conducted under visual flight rules (VFR) as a U.S. Government operation by the Department of Interior, Bureau of Land Management. After loading passengers, the pilot initiated an engine start. However, a main rotor blade tie-down strap remained attached to one of the rotor blades.
Sequence of Events
As the rotor blades began to rotate, the tie-down strap came into contact with the upper end of the vertical stabilizer. The impact crushed the leading edge of the stabilizer in an aft direction. Additionally, the helicopter's tail boom sustained deformation and wrinkling just forward of the tail rotor gearbox.
Damage Assessment
The vertical stabilizer received structural damage, and the tail boom was compromised in the area near the tail rotor transmission. No other damage or injuries were reported in the source.
Probable Cause
The probable cause of the incident was the failure to remove the main rotor blade tie-down strap prior to engine start.