On August 24, 1991, a Bell L4 EXPERIMENTAL (registration N2770X) operated by Bell Helicopter Textron, Inc. was involved in an aviation accident near Arlington, TX. Investigators recorded the probable cause as: THE PILOT'S FAILURE TO MAINTAIN ADEQUATE ROTOR RPM DURING THE PLANNED AUTOROTATION AND HIS IMPROPER TOUCHDOWN. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
During a test flight of a new helicopter, a planned autorotation resulted in a hard landing. The main rotor blade contacted and severed the tailboom after multiple bounces. No mechanical failure was reported.
Incident Overview
A flight test pilot was conducting height/velocity maneuvers on a manufacturer's new helicopter. During the test flight, a planned autorotation was initiated to the runway. The helicopter subsequently experienced a hard landing, during which a main rotor blade contacted the tailboom, severing it.
Eyewitness Account
An eyewitness reported that the helicopter touched down on the rear skids and bounced several times before the tailboom separated from the rest of the aircraft. The sequence of bounces preceded the structural failure.
Pilot Report
The pilot reported no mechanical failure prior to or during the incident. The exact cause of the hard landing remains undetermined based on available information.
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