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ASN Wikibase Occurrence # 200029
Last updated: 28 March 2021
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Date:27-SEP-2017
Time:10:00
Type:Silhouette image of generic AS50 model; specific model in this crash may look slightly different
Eurocopter AS 350B2 Ecureuil
Owner/operator:Chaparral Air Group
Registration: N515ET
C/n / msn: 3425
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Substantial
Category:Accident
Location:Fullerton Municipal Airport (KFUL), Fullerton, CA -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Training
Departure airport:Long Beach, CA (LGB)
Destination airport:Fullerton, CA (FUL)
Investigating agency: NTSB
Narrative:
The check pilot reported that he was administering an annual standardization check ride in the public helicopter. The last maneuver evaluated was a hydraulic failure that would terminate by accomplishing a simulated run-on landing.
The maneuver was initiated when the evaluated pilot established an out-of-ground-effect (OGE) hover on the downwind leg of the pattern. The check pilot engaged the hydraulic test button on the center console to “simulate a hydraulic failure.” The evaluated pilot lowered the nose and established forward airspeed to maintain controllability. He maintained stabilized forward flight on the downwind leg, and the check pilot disengaged the hydraulic test button. The check pilot moved the hydraulic cutoff switch to the “off” position, and the hydraulic system was disengaged. The evaluated pilot remained on the controls and established a shallow approach until about 3 ft above the runway.
Over the runway, the evaluated pilot allowed the helicopter’s airspeed to decrease, and the check pilot stated, “Keep the speed up.” The evaluated pilot responded by lowering the nose; however, an uncontrollable rapid left yaw ensued.
The check pilot took control of the helicopter and attempted to keep the helicopter over the runway, but the nose pitched down, and the main rotor blades struck the ground. The check pilot decreased the fuel control, and the helicopter settled upright on the runway.
The helicopter sustained substantial damage to the windscreen above the cabin, the tailboom, and tail rotor drive system.
The METAR at the accident airport reported that, at the time of the accident, the wind from 250° at 3 knots, the skies were clear, and the temperature was 72°F.
According to the Operator’s Flight Manual:
In case of loss of hydraulic pressure, the recommended safety speed range is from 40 to 60 kt.
CAUTION:
DO NOT ATTEMPT TO CARRY OUT HOVER FLIGHT OR ANY LOW SPEED MANEUVER WITHOUT HYDRAULIC PRESSURE 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.
Postaccident examination revealed no mechanical malfunctions or anomalies that would have precluded normal operation.

Probable Cause: The pilot under evaluation’s failure to maintain adequate airspeed during a simulated hydraulic failure, which resulted in a loss of helicopter control. Contributing to the accident was the check pilot’s delayed remedial action.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20170927X35946&key=1
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N515ET

Accident investigation:
cover
  
Investigating agency: NTSB
Status: Investigation completed
Duration: 8 months
Download report: Final report


Revision history:

Date/timeContributorUpdates
29-Sep-2017 17:00 Geno Added
21-Jun-2018 20:00 ASN Update Bot Updated [Operator, Total occupants, Departure airport, Destination airport, Source, Narrative]
22-Jun-2018 06:13 ASN Update Bot Updated [Source]
23-Jun-2018 09:40 harro Updated [Source, Narrative]
12-Jan-2020 17:18 Aerossurance Updated [Aircraft type]

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