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ASN Wikibase Occurrence # 77935
Last updated: 7 May 2019
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Date:24-SEP-2010
Time:16:34
Type:Silhouette image of generic AS50 model; specific model in this crash may look slightly different
Eurocopter AS 350B2 Ecureuil
Owner/operator:Dekalb County Police Services
Registration: N91DK
C/n / msn: 3497
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Covington Municipal Airport, 3 nm N of Covington, Georgia -   United States of America
Phase: Landing
Nature:Unknown
Departure airport:Covington, GA (9A1)
Destination airport:Covington, GA (9A1)
Narrative:
According to the pilot of the helicopter, the instructor simulated a hydraulics failure by “turning off” the flight control hydraulics switch, in order to perform a hydraulics-off, run-on landing as the remedial action to the simulated emergency. As the helicopter slowed over the runway, the nose yawed to the left, and the pilot was unable to correct the yaw with right pedal input. The instructor took control of the helicopter, and completed a low-level, left-hand orbit to demonstrate and complete the maneuver. As the helicopter completed the left orbit and lined up for landing, it “rolled wings level” but then continued to roll to the right and collided with terrain. The pilot said that the entire maneuver was conducted hydraulics-off, and that he felt the instructor had control of the helicopter until it rolled past wings-level to the right. The pilot added that the instructor had successfully completed a similar maneuver earlier in the day, without restoring the flight control hydraulics. According to the manufacturer's Flight Manual (Emergency Procedures) and the Flight Manual Supplement, Hydraulic Pressure Failure Training Procedures, "CAUTION: DO NOT ATTEMPT TO CARRY OUT HOVER FLIGHT OR ANY LOW SPEED MANEUVER WITHOUT HYDRAULIC PRESSSURE ASSISTANCE. THE INTENSITY AND DIRECTION OF THE CONTROL FEEDBACK FORCES WILL CHANGE RAPIDLY. THIS WILL RESULT IN EXCESSIVE PILOT WORKLOAD, POOR AIRCRAFT CONTROL, AND POSSIBLE LOSS OF CONTROL." Both the pilot and the instructor stated that there was nothing wrong with the performance and handling of the helicopter.
Probable Cause: The flight instructor's loss of control of the helicopter during the intentional demonstration of a low speed, hydraulics-off maneuver, that was warned against in the helicopter manufacturer's flight manual.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20100925X01917&key=1
FAA register: 2. FAA: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?omni=Home-N-Number&nNumberTxt=91DK

Accident investigation:
cover
  
Investigating agency: 
Status: Investigation completed
Duration:
Download report: Final report


Revision history:

Date/timeContributorUpdates
24-Sep-2010 23:21 slowkid Added
25-Sep-2010 11:57 FLYINGBROTHER1 Updated
07-Oct-2010 13:51 Anon. Updated
26-Oct-2011 17:04 RobertMB Updated
31-Jul-2014 02:10 Dr. John Smith Updated
21-Dec-2016 19:25 ASN Update Bot Updated
26-Nov-2017 18:09 ASN Update Bot Updated

Corrections or additions? ... Edit this accident description