Bell 47G-2 accident near Wall Lake, Iowa, August 26, 1990
On August 26, 1990, a Bell 47G-2 (helicopter), registered N90529, was substantially damaged in an accident near Wall Lake, Iowa. 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 FAILURE OF THE PILOT TO MAINTAIN ROTOR RPM DURING TAKEOFF. THE HIGH DENSITY ALTITUDE AND UPHILL TERRAIN WERE FACTORS.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 26, 1990
- Place
- Wall Lake, Iowa · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 47G-2 · all 47G-2s on the register
- Registration
- N90529 · registry record · serial NT1958-1
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
AFTER REFUELING & RELOADING THE HELICOPTER WITH A SPRAY SOLUTION AT A FIELD SITE, A TAKEOFF WAS INITIATED IN CALM WIND CONDITIONS. THE PLT RPRTD THAT THE LOCATION REQUIRED HIM TO TAKE OFF UPSLOPE. HE STATED THAT THE RPM DROPPED SLIGHTLY, BUT REMAINED IN THE GREEN ARC DURING THE UPSLOPE PORTION OF THE TAKEOFF. AS THE HELICOPTER CROSSED A FENCE & THE TERRAIN STARTED SLOPING DOWNHILL, THE HELICOPTER FLEW OUT OF GROUND EFFECT. THE PLT RPRTD HE LEVELED THE HELICOPTER, THEN BEGAN A SLIGHT DSCNT TO INCREASE RPM & AIRSPEED. HOWEVER, THE ROTOR RPM DECAYED & JUST BEFORE TOUCHDOWN, THE HELICOPTER YAWED 90 DEG TO THE RIGHT. AFTER TOUCHDOWN, THE HELICOPTER ROLLED OVER. DENSITY ALT WAS ESTD TO BE 3216 FT.
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: commercial pilot
- Ratings: single-engine land; single-engine sea; instrument: helicopter; rotorcraft: helicopter
- Flight time: 2,000 hours in all; 75 in this make and model; 75 in the last 90 days; 30 in the last 30 days; 1,500 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: frt
The aircraft
- Airframe total time: 1,061 hours
- Last inspection: annual inspection, December 18, 1989; 142 hours since
- Maximum gross weight: 2,850 lb
- Seats: 1
- Landing gear: fixed
- Engine: Lycoming VO-435-A1F (piston); 0 hours total
The flight
- Departed from: NONE
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 1 statute miles
- Sky: not recorded; scat
- Temperature: 86°F (30°C), dew point 77°F (25°C)
- Altimeter: 29.00 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 N90529 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.