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ASN Wikibase Occurrence # 170279
Last updated: 26 July 2021
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Date:04-OCT-2014
Time:01:55
Type:Silhouette image of generic B06 model; specific model in this crash may look slightly different
Bell 206L-1 LongRanger II
Owner/operator:Air Evac Ems Inc
Registration: N335AE
MSN: 45659
Fatalities:Fatalities: 3 / Occupants: 4
Aircraft damage: Written off (damaged beyond repair)
Location:Wichita Falls, TX -   United States of America
Phase: En route
Nature:Ambulance
Departure airport:Waurika, OK (None)
Destination airport:Wichita Falls, TX
Narrative:
The pilot reported that he was making an approach to a hospital helipad into light wind at night when he chose to go around because he felt that the approach was too high and fast. The pilot lowered the helicopter’s nose, added power, and raised the collective, and the helicopter then entered a rapid, “violent” right spin. A review of the last 43 seconds of the helicopter’s flight track data revealed that, as the helicopter approached the helipad, it descended from 202 to 152 ft and decelerated from a ground speed of about 9 to 5 knots before it turned right. The pilot attempted to recover from the uncommanded spin by applying left antitorque pedal and cyclic, but he was unable to recover, and the helicopter then spun several times before impacting power lines/terrain. Postaccident examination of the helicopter and the engine revealed no mechanical anomalies that would have caused the helicopter’s uncommanded right spin. The helicopter was under its maximum allowable gross weight at the time of the accident, and the wind was less than 4 knots. 
Federal Aviation Administration guidance states that the loss of tail rotor effectiveness could result in an uncommanded rapid yaw, which, if not corrected, could result in the loss of aircraft control. The guidance further indicates that, at airspeeds below translational lift, the tail rotor is required to produce nearly 100 percent of the directional control and that, if the required amount of tail rotor thrust is not available, the aircraft will yaw right. Therefore, it is likely that that the pilot did not adequately account for the helicopter’s low airspeed when he applied power to go around, which resulted in a sudden, uncommanded right yaw due to a loss of tail rotor effectiveness.
 
 


Probable Cause: The pilot’s failure to maintain yaw control when he applied power to execute a go-around at a low airspeed in dark, night conditions, which resulted in a rapid, uncommanded right yaw due to a loss of tail rotor effectiveness.



Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20141004X60516&key=1
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=335AE

Location


Revision history:

Date/timeContributorUpdates
04-Oct-2014 12:43 gerard57 Added
04-Oct-2014 14:34 Aerossurance Updated [Source, Narrative]
04-Oct-2014 16:44 Geno Updated [Destination airport, Source]
04-Oct-2014 23:06 Geno Updated [Source]
06-Oct-2014 00:30 Geno Updated [Aircraft type, Registration, Cn, Operator, Source, Narrative]
06-Oct-2014 19:49 harro Updated [Registration, Narrative]
09-Oct-2014 07:27 gerard57 Updated [Total fatalities, Source, Narrative]
10-Oct-2014 14:15 Aerossurance Updated [Departure airport, Source, Narrative]
24-Jul-2015 14:40 Aerossurance Updated [Narrative]
25-Jul-2015 09:25 Aerossurance Updated [Source, Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
30-Nov-2017 19:29 ASN Update Bot Updated [Operator, Total fatalities, Other fatalities, Departure airport, Destination airport, Source, Narrative]
30-Jan-2019 21:23 Aerossurance Updated [Location, Source]

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