- Date
- July 17, 1998, 12:30 local (18:30 UTC)
- Place
- Olathe, CO
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N92HABell 47-GB31
- Weather
- Visual (VMC) · Day
- Status
- Completed · report September 28, 1999
- Report
- Approved by Office Director
- FAA report
- 19980717027069A
- Case key
- 43169
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
The pilot's inadequate in-flight planning which resulted in an encounter with his own wake turbulence. Related factors were high density altitude and wake turbulence.
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
While on its third aerial application pass, to dispense a rinse load, the helicopter flew into its own wake turbulence and had insufficient power to overcome the settling which ensued. The helicopter struck the ground in a nose low attitude and the main rotor blades severed the tail boom. Density altitude at the time was computed to be approximately 8,900 feet.
Factual narrative
On July 17, 1998, at 1230 mountain daylight time, a Bell 47-GB31 helicopter, N92HA, settled to a hard landing while maneuvering near Olathe, Colorado, during an aerial application flight. The commercial pilot and sole occupant was not injured and the helicopter sustained substantial damage. The flight was being operated as an aerial application flight under Title 14 CFR Part 137, and no flight plan was filed. Visual meteorological conditions prevailed.
According to the pilot, he was dispensing a rinse load and had made three passes over the same path. He said the wind came up as he turned the helicopter for another pass and he flew into his own wake turbulence. The pilot said he had insufficient power to overcome the ensuing descent and the helicopter settled onto the ground in a nose low attitude. This caused the main rotor blades to strike the tail boom and sever it from the aircraft.
Density altitude at the time was computed to be approximately 8,900 feet.
Aircraft
- Registration
- N92HA
- Reported as
- Bell 47-GB31
- Category
- Helicopter
- Serial number
- 3696
- Airframe hours
- 6,260
- Engine
- Lycoming TVO-435-B1A, 260 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Aerial application · Part 137
- Registered owner
- Olathe Spray Service, Inc.
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · January 29, 1998 · 35 hours before
- Departed
- 1C04
- Airport
- ICO4 · Clifford Field, runway 17, 4,000 × 100 ft, dirt
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 52
- Certificate
- Commercial
- Airplane ratings
- Single-engine land
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Left
- Flight hours
- 20,245 total · 351 in this make and model · 334 in the last 90 days · 87 in the last 30 days · 6 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 350° at 8 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 88 °F, dew point 45 °F
- Altimeter
- 30.00 inHg
- Observed at
- MTJ, 30 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.