# NTSB DEN07LA132: Bell 206B, N568TD, Broomfield, CO, August 1, 2007 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: August 1, 2007, 16:35 local (22:35 UTC) - Place: Broomfield, CO - Coordinates: 39.908889, -105.117225 - Nearby events: https://openairdocs.org/map.md?lat=39.9089&lon=-105.1172&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor, 2 uninjured - Status: Completed, report September 27, 2007 - Report: Approved by Office Director - Parties: Bell Helicopter Textron, Inc., FAA Flight Standards District Office - NTSB case key (mKey): 66357 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN07LA132 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/66357/pdf - Page: https://openairdocs.org/ntsb/DEN07LA132 ## Probable cause The pilot's failure to maintain control of the helicopter, resulting in an inadvertent dynamic rollover. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, takeoff - aircraft control - not maintained, pilot in command (cause) - Roll over, takeoff - dynamic rollover - inadvertent, pilot in command (cause) ## Analysis According to the pilot, this was his sixth sightseeing flight of the day. He had just landed and three passengers disembarked. Three other passengers boarded the helicopter. As the pilot brought the throttle to full rpm and increased torque, the helicopter turned left about 15 degrees. Approximately 3 inches of opposite pedal was used to bring the helicopter back to its original heading. The pilot continued to increase torque and as the skids started to come off the ground, the nose pitched up rapidly and the helicopter rolled to the right. The left skid was about 3 inches off the ground during the yaw. The right skid never left the ground. Full forward and left cyclic had no effect. The pilot then lowered collective and tried to roll off the throttle. The helicopter rolled right until the main rotor blades contacted the ground. A piece of main rotor blade struck a nearby hangar. The pilot reported no control anomalies and a subsequent examination revealed no discrepancies. FAA's "Rotorcraft Flying Handbook" (FAA-H-8083-21) defines "dynamic rollover" as "the tendency of a helicopter to continue rolling when the critical angle is exceeded, if one gear is on the ground, and the helicopter is pivoting around that point." ## Factual narrative On August 1, 2007, approximately 1635 mountain daylight time, a Bell 206B, N268TD, piloted by an airline transport-certificated pilot, was substantially damaged when it yawed to the left and rolled over to the right and struck the helipad while taking off at Rocky Mountain Metropolitan Airport (BJC), Broomfield, Colorado. Visual meteorological conditions prevailed at the time of the accident. The sightseeing flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot and two passengers aboard the helicopter received minor injuries. One passenger was not injured. The local flight was originating at the time of the accident. According to the pilot, this was his sixth sightseeing flight of the day. He had just landed and three passengers disembarked. Three other passengers boarded the helicopter. As the pilot brought the throttle to full rpm and increased torque, the helicopter turned left about 15 degrees. Approximately 3 inches of opposite pedal was used to bring the helicopter back to its original heading. The pilot continued to increase torque and as the skids started to come off the ground, the nose pitched up rapidly and the helicopter rolled to the right. The left skid was about 3 inches off the ground during the yaw. The right skid never left the ground. Full forward and left cyclic had no effect. The pilot then lowered collective and tried to roll off the throttle. The helicopter rolled right until the main rotor blades contacted the ground. A piece of main rotor blade struck a nearby hangar. The pilot reported no control anomalies. On August 15, 2007, the helicopter was examined by FAA and Bell Helicopter investigators. They reported finding no anomalies. FAA's "Rotorcraft Flying Handbook" (FAA-H-8083-21) defines "dynamic rollover" as "the tendency of a helicopter to continue rolling when the critical angle is exceeded, if one gear is on the ground, and the helicopter is pivoting around that point." It elaborates: "A helicopter is susceptible to a lateral rolling tendency, called dynamic rollover, when lifting off the surface. For dynamic rollover to occur, some factor has to first cause the helicopter to roll or pivot around a skid...until its critical rollover angle is reached. Then, beyond this point, main rotor thrust continues the roll and recovery is impossible. If the critical rollover angle is exceeded, the helicopter rolls on its side regardless of the cyclic corrections made." ## Aircraft - Registration: [N568TD](https://openairdocs.org/deregistered/N568TD-2017-05-15), registration cancelled 2017-05-15, S/N 2976, built 1980 (OpenAirDocs) - Reported make and model: Bell 206B - Registry model: [Bell 206B](https://openairdocs.org/model/bell-206b) (registry code 1181511) (OpenAirDocs) - Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 2976 - Airframe hours: 9353 - Engines: Rolls Royce 250-620B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 91 - Operator: Rotors of the Rockies - Registered owner: Vertical Lift, LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, May 1, 2007 - Departed: BJC, Broomfield, CO - Destination: BJC - Airport: BJC, Rocky Mountain Metropolitan ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 60; injuries: minor; flight instructor, airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 2, with waivers/limitations; last flight review March 1, 2007; seat: right; flight hours: 17,867 total, 106 in this make and model, 16,246 as pilot in command, 46 in the last 90 days, 15 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 60° at 8 knots - Visibility: 30 statute miles - Lowest ceiling: 20,000 ft broken - Temperature: 91 °F, dew point 46 °F - Altimeter: 30.14 inHg - Observed at: BJC 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.