Helicopter rollover during approach to mountain heliport

Casualties unknown • Juneau, AK, US

A commercial pilot experienced a loss of rotor RPM while approaching a mountain top heliport, leading to an off-target touchdown and subsequent rollover.

What happened

A certificated commercial pilot was performing a northerly approach to a heliport located at 3,400 feet MSL on a mountaintop. As the pilot neared the intended landing site, he reduced approach airspeed while simultaneously increasing collective pitch. This maneuver caused the rotor RPM to decay.

Due to the loss of engine performance, the pilot was unable to reach the intended landing area and was forced to hover over and eventually touch down on uneven terrain approximately thirty feet short and downhill from the target site. The pilot attempted to recover the rotor RPM by applying throttle and lowering the collective pitch while keeping the skids on the uphill slope.

In an effort to reposition the aircraft, the pilot applied left pedal input and increased collective pitch. This action caused the left skid to impact the ground, resulting in a rollover of the helicopter. The aircraft sustained substantial damage to its fuselage, tail boom, and rotor system. The pilot was not injured.

At the time of the accident, weather conditions featured clear skies and unlimited visibility. Winds were gusty from the southeast at 10 to 15 knots, with a temperature of approximately 70 degrees F.

Probable cause

The pilot's attempt to increase collective pitch while reducing airspeed caused a decay in rotor RPM, leading to an unplanned touchdown on uneven terrain and a subsequent rollover during repositioning maneuvers.

Frequently asked questions

What happened in the 1999-07-15 Hughes 269A accident near Juneau, AK?

A commercial pilot experienced a loss of rotor RPM while approaching a mountain top heliport, leading to an off-target touchdown and subsequent rollover.

What aircraft was involved and where did it happen?

The accident on 1999-07-15 involved a Hughes 269A, registration N8926F, at Juneau, AK.

What was the probable cause of the accident?

The pilot's attempt to increase collective pitch while reducing airspeed caused a decay in rotor RPM, leading to an unplanned touchdown on uneven terrain and a subsequent rollover during repositioning maneuvers.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X19135. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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