# NTSB CHI05CA147: Bell 47G, N8505F, Twin Brooks, SD, May 19, 2005 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: May 19, 2005, 18:00 local (23:00 UTC) - Place: Twin Brooks, SD - Coordinates: 45.230556, -96.566108 - Nearby events: https://openairdocs.org/map.md?lat=45.2306&lon=-96.5661&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report September 13, 2005 - Report: Approved by Office Director - Parties: FAA - NTSB case key (mKey): 61517 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI05CA147 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/61517/pdf - Page: https://openairdocs.org/ntsb/CHI05CA147 ## Probable cause The pilot's inadequate lookout and his failure to maintain clearance with the power lines. A factor was the low altitude at which the helicopter was operating. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, maneuvering - aerial application - low altitude flight/maneuver, pilot in command - visual lookout - inadequate, pilot in command (cause) - clearance - not maintained, pilot in command (cause) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - ground ## Analysis The helicopter collided with power lines during an aerial application flight. The pilot reported that he saw the power lines just prior to contacting them. He stated the lines hit the bubble then they traveled over the top of the helicopter contacting the main rotor shaft. He stated the helicopter then settled in a level attitude onto the tracks. The pilot stated he was spraying for the purpose of weed control along the Burlington Northern Santa Fe railroad when the accident occurred. The pilot stated he was about 2.75 miles into the 3 mile run when the helicopter contacted the lines. The pilot reported that he saw a pole to his left, but it was off in the distance. The pole on his right, which he did not see, was nestled in a group of trees. The pilot reported he was flying at an altitude of 15 to 20 feet above the tracks at an airspeed of 43 to 45 miles per hour. He stated the bubble was clean and the sun was to his back as he flew to the east. ## Factual narrative On May 19, 2005, at 1800 central daylight time, N8505F, a Bell 47G-3B-1, collided with power lines during an aerial application flight in Twin Brooks, South Dakota. The commercial pilot received minor injures. The helicopter was substantially damaged. The 14 Code of Federal Regulations Part 137 flight was operating in visual meteorological conditions without a flight plan. The local flight originated at Summit, South Dakota, at 1630. The pilot reported that he saw the power lines just prior to contacting them. He stated the lines hit the bubble then they traveled over the top of the helicopter contacting the main rotor shaft. He stated the helicopter then settled in a level attitude onto the tracks. The pilot stated he was spraying for the purpose of weed control along the Burlington Northern Santa Fe railroad when the accident occurred. The pilot stated he was about 2.75 miles into the 3 mile run when the helicopter contacted the lines. The pilot reported that he saw a pole to his left, but it was off in the distance. The pole on his right, which he did not see, was nestled in a group of trees. The pilot reported he was flying at an altitude of 15 to 20 feet above the tracks at an airspeed of 43 to 45 miles per hour. He stated the bubble was clean and the sun was to his back as he flew to the east. ## Aircraft - Registration: [N8505F](https://openairdocs.org/deregistered/N8505F-2019-05-04), registration cancelled 2019-05-04, S/N 3379, built 1971 (OpenAirDocs) - Reported make and model: Bell 47G - Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs) - Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 3379 - Engines: Lycoming VO-435 reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Dakota Helicopter, Inc. - Airworthiness certificate: Special, Restricted (Special) - Departed: Summit, SD - Destination: Milbank, SD ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 48; injuries: minor; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; flight hours: 5,124 total, 2,000 in this make and model, 5,100 as pilot in command, 13 in the last 90 days, 13 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day ## 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 20050519034269A](https://openairdocs.org/incident/20050519034269A), May 19, 2005: Bell 47G3B1, Twin Brooks, SD, Substantial damage. (-23) On may 19, 2005, at approximately 6:15 pm CDT, a Bell helicopter aircraft m/n BHT-47-G3B1, N8505F, operated by commercial pilot [privacy data omitted]… ## Other investigations on N8505F (1) 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. - [NTSB FTW75FRG48](https://openairdocs.org/ntsb/FTW75FRG48), Dec 5, 1974: Bell 47GB31 (N8505F), Freer, TX, substantial damage 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.