# NTSB LAX01LA098: Bell 47-G3B1, N3084G, Winterhaven, CA, February 10, 2001 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: February 9, 2001, 19:00 local (Feb 10, 2001, 03:00 UTC) - Place: Winterhaven, CA - Coordinates: 33.710815, -116.229301 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.7108&lon=-116.2293&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report July 15, 2002 - Report: Approved by Office Director - Parties: Federal Aviation Administration - FSDO - NTSB case key (mKey): 51735 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX01LA098 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/51735/pdf - Page: https://openairdocs.org/ntsb/LAX01LA098 ## Probable cause A failure of the transmission free wheeling unit due to improper maintenance. A factor was the dark night visual condition. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, takeoff - initial climb - light condition - dark night (contributing factor) - maintenance - improper, other maintenance personnel (cause) ## Analysis The pilot was applying chemicals at night to a field of lettuce and had just taken off from his truck platform with 60 gallons of chemicals. He was about 20 feet above ground level and had a forward air speed of approximately 30 miles per hour when he heard a loud screeching sound, followed by a yaw to the left, a rapid decay of rotor rpm, and an increase/overspeed in engine rpm. The helicopter landed hard, collapsing the skids. Post accident examination of the transmission was conducted, revealing that the outer surface of the free wheeling unit of the inner gear assembly was worn below allowable limits at the roller/gear operating surface. The worn freewheeling inner ring gear allowed a mechanical disconnect between the engine output and the main rotor transmission, and resulted in a loss of main rotor speed and the subsequent hard landing. ## Factual narrative On February 9, 2001, about 1900 hours Pacific standard time, a Bell 47-G3B1, N3084G, landed hard near Winterhaven, California, following a drive train failure during a night agricultural spraying operation. The helicopter was owned and operated by Sundown Helicopters, Inc., of Yuma, Arizona, and was substantially damaged. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed for the flight, which was operating under 14 CFR Part 137. The flight was originating at the time of the occurrence. The pilot reported that he was applying chemicals to a field of lettuce and had just taken off from his truck platform with 60 gallons of chemicals. He said that he was about 20 feet above ground level and had a forward air speed of approximately 30 miles per hour when he heard a loud screeching sound, followed by a yaw to the left, a rapid decay of rotor rpm, and an increase/overspeed in engine rpm. The helicopter landed hard, collapsing the skids. Post accident examination of the transmission was conducted on February 10, 2001. Examination of the free wheeling unit revealed the outer surface of the inner gear assembly was worn below allowable limits at the roller/gear operating surface. No other discrepancies were noted. ## Aircraft - Registration: [N3084G](https://openairdocs.org/deregistered/N3084G-2020-10-03), registration cancelled 2020-10-03, S/N 2916 (OpenAirDocs) - Reported make and model: Bell 47-G3B1 - Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs) - Category: Helicopter - Serial number: 2916 - Airframe hours: 6322 - Engines: Avco Lycoming TVO-435-B1A 280 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Sundown Helicopters, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, November 27, 2000, 38 hours before - Departed: NONE, Yuma, AZ ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; injuries: none; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--w/ waivers/lim; last flight review June 29, 2000; seat: left; flight hours: 18,930 total, 2,500 in this make and model, 18,400 as pilot in command, 52 in the last 90 days, 29 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 30° at 1 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 50 °F ## 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 20010209002979A](https://openairdocs.org/incident/20010209002979A), Feb 9, 2001: Bell 47G3B1, Winterhaven, CA, Substantial damage. (-23)See attached narrative ptrs #LAX01LA098 (19) on February 9, 2001, about 1900 hours MST, a Bell 47-G3B1, N3084G, collided with the ground following a drive… ## Other investigations on N3084G (3) 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 LAX99LA049](https://openairdocs.org/ntsb/LAX99LA049), Dec 4, 1998: Bell 47G-3B-1 (N3084G), Winterhaven, CA, substantial damage. Probable cause: The failure of the pilot to maintain rotor rpm. A factor was his attempt to take off over gross weight. - [NTSB LAX80FUA22](https://openairdocs.org/ntsb/LAX80FUA22), Sep 7, 1980: Bell 47G-3B (N3084G), Bellflower, CA, substantial damage - [NTSB LAX75DUG22](https://openairdocs.org/ntsb/LAX75DUG22), Nov 21, 1974: Bell 47G3B1 (N3084G), Joshua Tree, CA, 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.