BELL HELICOPTER TEXTRON 206L-1 near La Junta, CO — 2013-05-07

Probable cause

The pilot's inadequate compensation for wind during low-altitude operations, which resulted in a loss of tail rotor effectiveness.

NTSB narrative

The purpose of the flight was to videotape a pipeline corridor. The commercial pilot reported that, while flying over mainly flat rural areas, the helicopter entered an uncommanded left yaw, returned to straight flight for about 1 to 2 seconds, and then entered an uncommanded right yaw that continued until the helicopter impacted the ground. GPS data from the camera used to videotape the pipeline corridor indicated that the helicopter's groundspeed was about 37 knots when it entered the uncommanded left yaw. Weather information from an airport about 5 miles away from the accident site indicated that the helicopter was flying with a tailwind of 11 knots gusting to 16 knots, which resulted in a calculated airspeed of between 22 and 26 knots. A postaccident examination of the airframe, engine, and control system revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The helicopter was operating in a high-power, low-airspeed condition that required the pilot to be especially aware of wind direction to avoid tailwinds, which can result in a loss of control due to a loss of tail rotor effectiveness. Based on the available information, it is likely that the pilot's operation of the helicopter at a low airspeed with a gusting tailwind resulted in the loss of tail rotor effectiveness.

Analysis

Primary failure mode

Loss of control

First missed decision gate

Pilot could have maintained better control to prevent uncommanded yaw.

NTSB coding

• Loss of tail rotor effectiveness · Maneuvering

Evidence available

• ADS-B / radar
• Photos
• 8 docket documents

Docket documents8

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Occupant Statements to Sheriff's Dept.interview
• AC 90-95 Unanticipated Right Yaw in Helicoptersother
• Excerpt from FAA Helicopter Flying Handbookother
• On Board Image Recorder - Specialist's Summary Reportphotos
• Photos and Imagesphotos
• GPS Data Factual Reportreport
• GPS Data Factual Report - Attachment 1report

Related mishaps

• AIRBUS EC 130 T2

  2018-08-03 · Mullen, NE

• BRANTLY B 2B

  2017-10-01 · Midland, MI · 1 fatality

• ROBINSON HELICOPTER R44

  2017-07-08 · Ireland, IN

• ROBINSON HELICOPTER COMPANY R44 II

  2017-07-06 · Ronan, MT

• BELL 206 - B11

  2015-05-29 · Caledonia, MI

• BELL BHT407

  2013-04-25 · Big Fork, MT