On March 21, 1987, a Bell 47G-3B-1 (registration N62462) was involved in an aviation accident near Odessa, TX. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An investigation found that a helicopter touched down on its skid heels with low rotor RPM, causing the tail boom to rise and be severed by the main rotor blades.
Landing Sequence
During a landing, the helicopter touched down on the heels of its skids, with the left skid contacting the ground first. At the time, the rotor RPM was slightly low.
Post-Impact Dynamics
Following touchdown, the tail boom moved upward while the main rotor blades flexed downward. The downward-flexing main rotor blades then contacted and severed the tail boom. This caused the tail rotor assembly to separate and fall to the ground.
Evidence
Post-accident examination revealed fresh marks on the main rotor hub assembly where it had banged against the main rotor droop stops.