- Date
- February 9, 2001, 19:00 local (Feb 10, 2001, 03:00 UTC)
- Place
- Winterhaven, CA
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Initial climb
- Aircraft
- N3084GBell 47-G3B1
- Weather
- Visual (VMC) · Night/dark
- Status
- Completed · report July 15, 2002
- Report
- Approved by Office Director
- Parties
- Federal Aviation Administration - FSDO
- FAA report
- 20010209002979A
- Case key
- 51735
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
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
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
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
- Reported as
- Bell 47-G3B1
- Category
- Helicopter
- Serial number
- 2916
- Airframe hours
- 6,322
- Engine
- 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
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 53
- Injuries
- None
- Certificates
- 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.
Other investigations on N3084G · 3
Matched to the same aircraft by N-number and date.