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ASN Wikibase Occurrence # 42709
Last updated: 20 August 2021
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Date:01-APR-1999
Time:11:36
Type:Silhouette image of generic B06 model; specific model in this crash may look slightly different
Bell 206B JetRanger
Owner/operator:Papillon Grand Canyon Helicopt
Registration: N992UC
MSN: 421
Fatalities:Fatalities: 1 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Grand Canyon, Arizona -   United States of America
Phase: Initial climb
Nature:Training
Departure airport:GCN
Destination airport:
Investigating agency: NTSB
Narrative:
Shortly after takeoff and transition to forward flight, the helicopter's engine stopped. During the ensuing autorotative landing glide, a main rotor blade struck a tree about 30 feet above ground level and the helicopter fell to the ground. This was the first flight of the day and the helicopter had been stored outside overnight in conditions of cold temperatures and light snowfall without engine air inlet covers installed. Prior to the flight the engine was difficult to start. There were five aborted starts before the engine was successfully started. During the first three start attempts, fuel was introduced, ignition occurred, the engine acceleration hung at 30 percent, and the starts were aborted. After the third start attempt a mechanic noted that the engine inlets were approximately half blocked by snow and cleared the snow from the inlets using a towel. He did not check the plenum chamber aft of the particle separator and forward of the engine inlet for snow. In the wreckage, the plenum chamber inspection window was found to be opaque. After the accident, another company mechanic who had dealt with the same starting difficulty on another helicopter of the same type parked under the same circumstances without inlet covers, reported finding the plenum chamber of that helicopter contained several cups of snow. The engine manufacturer reported that tests of the engine had shown that ingestion of as little as 6 ounces of snow/slush could flame out the engine. The operator's procedure requiring that the last flight crew at the end of the day install the inlet covers on aircraft stored outside had not been followed.
Probable Cause: The failure of the flight crew to properly preflight the helicopter and to detect and remove accumulated snow from the engine inlets and plenum chamber. Factors in the accident were the clouded plenum chamber inspection window and the failure of preceding flight crew to install the engine inlet covers in accordance with the operator's procedure.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001205X00484&key=1
FAA register: 2. http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=992UC


Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
09-Apr-2015 21:21 Dr. John Smith Updated [Time, Location, Phase, Departure airport, Source, Narrative]
21-Dec-2016 19:24 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
26-Nov-2017 12:38 ASN Update Bot Updated [Operator, Departure airport, Source, Narrative]

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