# NTSB SEA07CA200: Bell 206B II, N164JS, Sheep Mountain, MT, July 16, 2007 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: July 16, 2007, 08:30 local (14:30 UTC) - Place: Sheep Mountain, MT - Coordinates: 44.557498, -111.775001 - Nearby events: https://openairdocs.org/map.md?lat=44.5575&lon=-111.7750&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report November 29, 2007 - Report: Approved by Office Director - Parties: Helena Flight Standards District Office - NTSB case key (mKey): 66228 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA07CA200 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/66228/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=66228 - Page: https://openairdocs.org/ntsb/SEA07CA200 ## Probable cause The external load net, attached directly to the cargo hook without the use of a long line, oscillated and made contact with the tail rotor system while maneuvering. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Miscellaneous/other, maneuvering - external load sling/harness - oscillation (cause) - Forced landing, descent - emergency - autorotation - initiated, pilot in command - On ground/water encounter with terrain/water, emergency landing - terrain condition - mountainous/hilly ## Analysis The helicopter was transporting supplies with a cargo net from one mountain site to another. The sling loads consisted of steel angle iron, which was bagged and secured with velcro, and then placed into the cargo net. After delivering the fourth load, the pilot lifted off with only an empty bag inside the net. The Bell 206B rotorcraft flight manual, in the supplement for external loading, states, "Control movements should be made smoothly and kept to a minimum to prevent oscillation of sling load." According to a witness, as the helicopter departed, the net "floated very close to the propeller [tail rotor], then floated back down." The net, which was attached directly to the helicopter cargo hook without the use of a long line, swung back up again and impacted the tail rotor, cutting the cargo net and releasing the bag. The pilot heard noise and "thumping" sounds, accompanied by vibrations and yawing, and realized that he had a tail rotor strike. The pilot entered an autorotation at "25 miles per hour and 200 feet" above a timbered slope. The pilot selected a small, sloped, clearing as a landing zone, and upon touchdown, the helicopter rolled over, coming to rest on it's right side. ## Factual narrative The helicopter was transporting supplies with a cargo net from one mountain site to another. The sling loads consisted of steel angle iron, which was bagged and secured with velcro, and then placed into the cargo net. After delivering the fourth load, the pilot lifted off with only an empty bag inside the net. The Bell 206B rotorcraft flight manual, in the supplement for external loading, states, "Control movements should be made smoothly and kept to a minimum to prevent oscillation of sling load." According to a witness, as the helicopter departed, the net "floated very close to the propeller [tail rotor], then floated back down." The net, which was attached directly to the helicopter cargo hook without the use of a long line, swung back up again and impacted the tail rotor, cutting the cargo net and releasing the bag. The pilot heard noise and "thumping" sounds, accompanied by vibrations and yawing, and realized that he had a tail rotor strike. The pilot entered an autorotation at "25 miles per hour and 200 feet" above a timbered slope. The pilot selected a small, sloped, clearing as a landing zone, and upon touchdown, the helicopter rolled over, coming to rest on it's right side. ## Aircraft - Registration: [N164JS](https://openairdocs.org/deregistered/N164JS-2007-12-26), registration cancelled 2007-12-26, S/N 955, built 1973 (OpenAirDocs) - Reported make and model: Bell 206B II - 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: 955 - Airframe hours: 5043 - Engines: Allison 250C20 385 horsepower turbo shaft - Damage: Substantial damage - Fire: On-Ground - Flight: External load, Part 133 - Operator: Ronald L. Young, doing business as Eagle Aero, Inc. - Registered owner: J.R. Simplot Company - Airworthiness certificate: Standard, Normal - Last inspection: June 1, 2007 - Departed: Mtn Drop Site, MT - Destination: Mtn Drop Site, MT - Airport: NONE, Off Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 74; injuries: minor; commercial, flight instructor; airplane ratings: multi-engine sea, single-engine land; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review May 1, 2007; seat: right; flight hours: 12,860 total, 3,000 in this make and model, 12,000 as pilot in command, 31 in the last 90 days, 8 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 30 statute miles - Lowest ceiling: none - Temperature: 64 °F - Altimeter: 29.92 inHg ## 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 20070716015039A](https://openairdocs.org/incident/20070716015039A), Jul 16, 2007: Bell 206B, Dillon, MT, Substantial damage. (-23) At approximately 0830 hours on July 16, 2007, at location 15.5 miles northwest of the island park reservoir, on the Montana side of the montana/idaho… ## Docket (2 files) The files NTSB released with the investigation on October 22, 2007, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=66228. 546 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 514 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40284192&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Witness Statement (item 2, .PDF, 32 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40413150&FileExtension=.PDF&FileName=Witness%20Statement-Redacted.PDF 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.