Aircraft Accident/Incident Report

Maple Grove, Minnesota 55369
Friday, August 9, 1991 7:50 CDT

NTSB Narrative Summary Released at Completion of Accident

THE PLT SAID HE HAD COMPLETED AERIAL APPLICATION OF MOSQUITO CTL TREATMENT & WAS RTRNG TO THE LOAD SITE. THE HELICOPTER WAS IN CRUISE FLT AT 300 FT ABV THE GND WHEN THE PLT '...NOTICED IT WAS REQUIRING MORE RIGHT CYCLIC CONTROL TO KEEP THE HELICOPTER LEVEL, ALSO BEGAN TO EXPERIENCE A LOSS IN ALTITUDE.' THE PLT NOTED THE ROTOR RPM HAD DROPPED TO 90%, BUT THERE WERE NO WARNING LIGHTS OR HORNS. THE ENG OUT AUDIO WARNING WAS PLACARDED 'INOPERATIVE' & THE PLT WAS AWARE THE OIL CHIP WARNING LIGHT WAS INOP. THE PLT MADE A FORCED LANDING IN AN ALFALFA FIELD. HE STATED '...DUE TO THE RIGHT CYCLIC INPUT I HAD TO LAND WITH A DRIFT TO THE RIGHT...THE RIGHT SKID GEAR SNAPPED, ROLLING OVER TO THE RIGHT.' AN INV REVEALED THE LEFT HOPPER WAS BLOCKED & STILL CONTAINED AN ESTD 100 TO 300 LBS OF MOSQUITO CONTROL AGENT. THIS LOAD RESULTED IN AN IMBALANCE WHICH WAS COUNTERED BY EXTREME CYCLIC INPUT. EXAM OF THE ENG REVEALED 'SEVERE EROSION' OF THE COMPRESSOR BLADES, AND HORSEPOWER PRODUCTION 'SIGNIFICANTLY BELOW PRODUCTION TEST SPECIFICATIONS.'

NTSB Probable Cause Narrative

THE PILOT'S FAILURE TO MAINTAIN DIRECTIONAL CONTROL OF THE HELICOPTER DURING THE FORCED LANDING. RELATED FACTORS ARE THE LOSS OF ENGINE POWER, LOSS OF ROTOR RPM, THE ERODED COMPRESSOR BLADES, THE PILOT'S OPERATION WITH KNOWN DEFICIENCIES IN EQUIPMENT AND INADEQUATE AIRCRAFT PREFLIGHT, AND THE BLOCKED SPRAY EQUIPMENT.

Event Information

Type of Event Accident
Event Date 8/9/1991
Event Day of the Week Friday
Time of Event 750
Event Time Zone Central Daylight Time
Event City MAPLE GROVE
Event State MINNESOTA
Event Country --
Zipcode of the event site 55369
Event Date Year 1991
Event Date Month 8
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude
Event Location Longitude
Event Location Airport
Event Location Nearest Airport ID
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles 0
Degrees magnetic from airport 0
Airport Elevation --
Weather Briefing Completeness Unknown
Investigator's weather source Pilot
Time of the weather observation 0
Direction of event from weather observation facility (degrees) 0
Weather Observation Facility ID
Elevation of weather observation facility 0
Distance of event from weather observation facility (units?) 0
Time Zone of the weather observation
Lighting Conditions Day
Lowest Ceiling Height 0
Lowest Non-Ceiling Height 0
Sky/Lowest/Cloud Conditions Clear
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 7
Air Temperature at event time (in degrees celsius) 24
Dew Point at event time (in degress fahrenheit) --
Wind Direction (degrees magnetic) 180
Variable Wind Indicator Unknown
Wind Speed (knots) 5
Wind Velocity Indicator Unknown
Wind Gust Indicator Unknown
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) --
Density Altitude (feet) --
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor --
Injury Total None 1
Injury Total Serious --
Injury Total All --
Investigating Agency FAA
NTSB Docket Number (internal use) 2093
NTSB Notification Source --
NTSB Notification Date --
NTSB Notification Time 0
Fiche Number and/or location -used to find docket information 46589
Date of most recent change to record Dec 12 2000 10:38AM
User who most recently changed record dbo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N73998
NTSB Number CHI91DER13
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 137: Agricultural
Type of Flight Plan filed None
Flight plan Was Activated? --
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name BELL
Aircraft Model 47G-3B-1
Aircraft Series Identifier 47G-3B-1
Aircraft Serial Number 2902
Certified Max Gross Weight 2950
Aircraft Category Helicopter
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 3
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection Annual
Date of Last Inspection Apr 15 1991 12:00AM
Airframe hours since last inspection 122
Airframe Hours 6015
ELT Installed No
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name CHURCHILL, SCOTT
Aircraft Owner Street Address 305 RIDGE ROAD
Aircraft Owner City LESUEUR
Aircraft Owner State MN
Aircraft Owner Country
Aircraft Owner Zipcode 56058
Operator is an individual? --
Operator Name CHURCHILL, SCOTT
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? Yes
Operator Street Address 305 RIDGE ROAD
Operator City LESUEUR
Operator State MN
Operator Country
Operator Zip code 56058
Operator Code CUHG
Owner has at least one certificate Yes - certificate holder
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Agriculture
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Unknown
Indicates Domestic or International Flight Unknown
Operator carrying Pax/Cargo/Mail Unknown
Type of Flying (Per_Bus / Primary) Aerial Application
Second Pilot on Board No
Departure Point Same as Event No
Departure Airport Code MIC
Departure City MINNEAPOLIS
Departure State MN
Departure Country
Departure Time 705
Departure Time Zone CDT
Destination Same as Local Flt crash at destination city
Destination Airport Code NONE
Destination City
Destination State MN
Destination Country
Specific Phase of Flight Landing
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Jan 2 2001 10:35AM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --