Bell 47-G2 accident near Hatley, Wisconsin, July 10, 1990
On July 10, 1990, a Bell 47-G2 (helicopter), registered N6768D, was substantially damaged in an accident near Hatley, Wisconsin. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE PARTIAL LOSS OF POWER DUE TO STICKING INTAKE VALVES.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 10, 1990
- Place
- Hatley, Wisconsin · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 47-G2 · all 47-G2s on the register
- Registration
- N6768D · no longer on the register · serial 2441
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
THE HELICOPTER WAS LOADED WITH CHEMICALS FOR AGRICULTURE DISPERSAL ON A TRUCK MOUNTED PLATFORM, TEN FEET ABOVE GROUND LEVEL. ON LIFTOFF THE ENGINE SUSTAINED A PARTIAL POWER REDUCTION DUE TO TWO STICKING INTAKE VALVES. THE AIRCRAFT DESCENDED INTO THE TERRAIN WHEN ALTITUDE PROVED INSUFFICIENT TO EFFECT AN AUTOROTATIONAL FORCED LANDING.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: helicopter; instrument: airplane; rotorcraft: helicopter
- Flight time: 2,080 hours in all; 375 in this make and model; 120 in the last 90 days; 70 in the last 30 days; 1,950 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 12,331 hours
- Last inspection: annual inspection, June 27, 1990; 40 hours since
- Maximum gross weight: 2,850 lb
- Seats: 3
- Landing gear: fixed
- Engine: Lycoming VO-435-A1F (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 290° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 61°F (16°C)
- Altimeter: 30.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N6768D the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.