# NTSB DEN01LA156: Aerospatiale AS350BA, N57843, Kemmerer, WY, September 6, 2001 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 5, 2001, 18:30 local (Sep 6, 2001, 00:30 UTC) - Place: Kemmerer, WY - Coordinates: 41.780555, -110.55027 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.7806&lon=-110.5503&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 20, 2002 - Report: Approved by Office Director - Parties: FAA Flight Standards Field Office - NTSB case key (mKey): 53183 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN01LA156 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/53183/pdf - Page: https://openairdocs.org/ntsb/DEN01LA156 ## Probable cause the loss of tail rotor effectiveness while air taxiing. Contributing factors were the high winds and gusts, and the pilot's limited experience in aircraft make/model. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, taxi - aerial - lack of total experience in type of aircraft, pilot in command (contributing factor) - loss of tail rotor effectiveness - encountered, pilot in command (cause) - weather condition - high wind (contributing factor) - weather condition - gusts (contributing factor) - In flight collision with terrain/water, descent - uncontrolled ## Analysis The pilot was aerial taxiing the helicopter to a parking area at 10 knots and into a slight quartering headwind. There was some thunderstorm activity west of the airport, and the nearest recorded winds were from 260 degrees at 20 knots, with gusts to 36 knots. As he turned towards the tie down area, there was a strong gust of wind from the left. The helicopter yawed to the left and full right pedal had no effect on arresting the spin. The helicopter struck the ground and rolled over. The pilot had 4,000 total flight hours in helicopters, but had recently transitioned to this make and model helicopter and had 8 hours in type. ## Factual narrative On September 5, 2001, at 1830 mountain daylight time, an Aerospatiale AS350BA, N57843, operated by Crew Concepts, Inc., of Boise, Idaho, was substantially damaged when it collided with terrain during aerial taxi at the Kemmerer Municipal Airport, Kemmerer, Wyoming. The commercial pilot, the sole occupant aboard, was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the positioning flight being conducted under Title 14 CFR Part 91. The flight originated from Pocatello, Idaho, at an undetermined time. In a telephone interview with the pilot, he said he was bringing the helicopter to Kemmerer for seismic survey support. He was aerial taxiing over the taxiway parallel to runway 16 when the helicopter started spinning. Opposite anti-torque pedal input had no effect in arresting the spin. The helicopter struck the ground, and rolled over on its side. The tail boom was severed and the main rotor system was torn from its mounts. Recorded winds at Evanston, Wyoming, located 52 miles southwest of Kemmerer, were from 260 degrees at 25 knots, gusting to 36 knots. The peak wind, recorded at 1929, was from 240 degrees at 47 knots. Upon learning of the accident, the operator dispatched its investigator to the accident scene to conduct a company investigation. According to his report, the pilot said he was aerial taxiing at 10 knots into a slight quartering headwind. There was some thunderstorm activity west of the airport. As the pilot turned towards the tie down area, "a very strong gust of wind seemed to hit the aircraft on the left side." The helicopter yawed to the left and full right pedal had no effect on arresting the counterclockwise spin. The report stated that the pilot lost control "due to severe/weather conditions...The application of full right pedal to correct yaw with no effect precipitated the situation whereby the pilot lost tail rotor effectiveness once the counterclockwise spin began." The report noted that Eurocopter, the helicopter manufacturer, issued Service Letter 1518-67-01 in April 2001, that described three similar mishaps. The report concluded, "Pilots must ensure that the application of LEFT pedal inputs are very slight with immediate correction using right pedal. Additionally, pilots are not to apply LEFT pedal inputs while passing through 'translational lift.' This restriction is to preclude the possibility of 'tail rotor vortex ring state' which may result in a spin to the left from which recovery is not possible." According to the operator, the pilot had 4,000 total flight hours in helicopters. He had recently transitioned to, and had 8 hours in, the AS350. ## Aircraft - Registration: N57843 (not matched to a registry record) - Reported make and model: Aerospatiale AS350BA - Category: Helicopter - Serial number: 1430 - Engines: Turbomeca Arriel 1B 529 horsepower turbo shaft - Damage: Substantial damage - Flight: Positioning, Part 91 - Operator: Crew Concepts, Inc. - Registered owner: Roberts Aircraft Co. - Airworthiness certificate: Standard, Normal - Departed: PIH, Pocatello, ID - Destination: EMM, Kemmerer, WY - Airport: EMM, Kemmerer Municipal ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: none; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; last flight review August 1, 2001; seat: right; flight hours: 3,900 total, 8 in this make and model, 3,600 as pilot in command, 45 in the last 90 days, 8 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 25 knots, gusting 36 - Visibility: 10 statute miles - Lowest ceiling: 11,000 ft broken - Temperature: 64 °F, dew point 36 °F - Altimeter: 30.00 inHg - Observed at: EVW, 52 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20010905025139A](https://openairdocs.org/incident/20010905025139A), Sep 5, 2001: Snias AS350BA, Kemmerer, WY, No damage. (-23) Pilot lost control of the helicopter while hovering to land. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.