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ASN Wikibase Occurrence # 58909
Last updated: 8 January 2020
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Date:07-MAR-2009
Time:10:00
Type:Silhouette image of generic H500 model; specific model in this crash may look slightly different
Hughes 369D
Owner/operator:Airwest Helicopters, Inc.
Registration: N501EF
C/n / msn: 270091D
Fatalities:Fatalities: 0 / Occupants: 3
Aircraft damage: Substantial
Category:Accident
Location:56 miles from Inyokern, CA -   United States of America
Phase: Unknown
Nature:Unknown
Departure airport:Inyokern, CA
Destination airport:Rogers Peak, CA
Investigating agency: NTSB
Narrative:
The helicopter pilot was flying passengers and equipment to a landing zone on a peak with an elevation of 9,993 feet. He made one high pass around the summit and assessed the wind as light and variable. He made a right circling approach and slowed from 60 knots to 40 knots. The airspeed suddenly decreased to 20 knots and the helicopter yawed 90 degrees to the right. He temporarily stabilized the situation, but then the helicopter went into a violent and uncontrollable right spin. It spun down vertically until it collided with terrain, rolled onto its right side, and slid about 75 yards before coming to a stop facing uphill. One of the passengers held a rotorcraft/helicopter pilot certificate. He indicated that on the first landing attempt the pilot appeared to be running out of left pedal. The second attempt was at a different angle to the landing zone, but once again the pilot seemed to run out of left pedal and the helicopter began to spin. The pilot could not recover during the attempt and the helicopter made three turns before colliding with the terrain. The Rotorcraft Flying Handbook refers to unanticipated yaw that does not subside on its own as a loss of tail rotor effectiveness. It notes that, if not corrected, this can lead to a loss of control. It may occur in all single-rotor helicopters at airspeeds less than 30 knots. A common cause is insufficient tail rotor thrust for a given power setting at higher altitudes, where tail rotor thrust and efficiency are reduced. Another potential cause is encountering a quartering tailwind from certain directions.
Probable Cause: The pilot's failure to maintain control while landing in a high density altitude environment due to a loss of tail rotor effectiveness.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20090308X11919&key=1


Revision history:

Date/timeContributorUpdates
09-Mar-2009 11:56 harro Updated
21-Dec-2016 19:25 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
01-Dec-2017 12:15 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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