On September 10, 1991, a Bell 47G-3B-2 (registration N2618D) operated by K & L Helicopters was involved in an aviation accident near Chula Vista, CA. Investigators recorded the probable cause as: The pilot's misjudgment of the autorotative landing flare, which resulted in a touchdown with forward ground speed and subsequent tumbling. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter equipped with float landing gear experienced an engine failure during a maintenance test flight autorotation, leading to a hard touchdown and tumble.
What happened
The pilot was conducting a maintenance test flight over land in a helicopter equipped with a float landing gear. The initial phase of the flight involved practicing autorotations, with the first attempt being successfully terminated through power recovery. During the subsequent autorotation maneuver, the engine failed unexpectedly. In an effort to execute a safe landing, the pilot attempted to flare the aircraft for touchdown. However, the pilot misjudged the timing and height of the autorotative landing flare. Consequently, the helicopter touched down with significant forward ground speed rather than coming to a near-hover or zero-velocity state. The impact caused the helicopter to tumble along its ground path.
The investigation
The source text does not provide specific details regarding mechanical examination or post-accident findings beyond the immediate sequence of events during the flight.
Probable cause
The pilot's misjudgment of the autorotative landing flare, which resulted in a touchdown with forward ground speed and subsequent tumbling.