ASN Wikibase Occurrence # 42709
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| Date: | Thursday 1 April 1999 |
| Time: | 11:36 |
| Type: |  Bell 206B JetRanger |
| Owner/operator: | Papillon Grand Canyon Helicopters |
| Registration: | N992UC |
| MSN: | 421 |
| Year of manufacture: | 1969 |
| Total airframe hrs: | 15860 hours |
| Fatalities: | Fatalities: 1 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Grand Canyon National Park Airport (GCN/KGCN), AZ -
 United States of America
|
| Phase: | Initial climb |
| Nature: | Training |
| Departure airport: | Grand Canyon National Park Airport, AZ (GCN/KGCN) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
On April 1, 1999, at 1136 hours mountain standard time, a Bell 206B, N992UC, was destroyed when it collided with a tree and fell to the ground during an autorotative emergency landing following loss of engine power shortly after takeoff from the Grand Canyon, Arizona, airport. Fatal injuries were sustained by the commercial pilot under instruction and serious injuries were sustained by the airline transport instructor pilot. Visual meteorological conditions prevailed for the 14 CFR Part 91 instructional flight. The helicopter was operated by Papillon Grand Canyon Helicopters and the flight was originating at the time for a local area flight.
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.
Accident investigation:
 |
|
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/time | Contributor | Updates |
|---|---|---|
| 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] |
| 13-Oct-2022 08:21 | Captain Adam | Updated [Operator, Location, Departure airport, Source, Narrative, Category, Accident report] |
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