- Date
- August 25, 1990, 19:40 local (Aug 26, 1990, 00:40 UTC)
- Place
- Wall Lake, IA
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Takeoff
- Aircraft
- N90529Bell 47G-2
- Weather
- Visual (VMC) · Day
- Status
- Completed · report December 14, 1992
- Report
- Approved by Office Director
- FAA report
- 19900825036029A
- Case key
- 14437
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 failure of the pilot to maintain rotor RPM during takeoff. The high density altitude and uphill terrain were factors.
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
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.
Aircraft
- Registration
- N90529
- Reported as
- Bell 47G-2
- Category
- Helicopter
- Serial number
- NT1958-1
- Airframe hours
- 1,061
- Engine
- Lycoming VO-435-A1F, 270 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Aerial application · Part 137
- Registered owner
- Northland Helicopters, Inc.
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · December 18, 1989 · 142 hours before
- Departed
- NONE
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
- 44
- Certificate
- Commercial
- Airplane ratings
- Single-engine land, Single-engine sea
- Instrument ratings
- Helicopter
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Front
- Flight hours
- 2,000 total · 75 in this make and model · 1,500 as pilot in command · 75 in the last 90 days · 30 in the last 30 days
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- Calm
- Visibility
- 1 statute miles
- Temperature
- 86 °F, dew point 77 °F
- Altimeter
- 29.00 inHg
- Observed at
- FOD, 41 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.
Other investigations on N90529 · 3
Matched to the same aircraft by N-number and date.