Aircraft Incident/Accident Report
Grand Forks Intl Airport

Grand Forks, North Dakota 58201
Friday, June 16, 2006 19:30 CDT

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NTSB Narrative Summary Released at Completion of Accident
The helicopter was substantially damaged when the tail rotor struck the taxiway during recovery from an intentional autorotation. The flight instructor and commercial pilot (dual student) were not injured. The flight instructor stated that the instructional flight included 180-degree autorotations, which were terminated into a hover with the addition of engine power. He reported that on the first autorotation the dual student flared high and during the recovery the rotor speed decayed requiring a landing on the taxiway. He noted that the dual student was subsequently instructed to increase engine power as collective was increased during the recovery in order to maintain rotor speed. On the second autorotation, he stated that the dual student flared lower and a "little more aggressively." He noted that as the dual student increased the collective, the rotor speed again decayed. The flight instructor stated that "as the collective continued upward the engine and rotor [speed] decreased." He "intervened on the controls and continued to increase the collective and throttle and level the aircraft, [when] the tail struck the taxiway." The flight instructor subsequently landed the helicopter after noting an airframe vibration. The flight instructor reported no malfunctions or failures prior to the accident.
NTSB Probable Cause Narrative
The dual student's failure to maintain rotor speed during the recovery from the intentional autorotation and the flight instructor's delayed remedial action. Contributing factors were the flight crew's intentional autorotation and dual student's misjudged flare.
Event Information
Type of EventAccident 
Event Date6/16/2006 
Event Day of the WeekFriday 
Time of Event1930 
Event Time ZoneCentral Daylight Time 
Event CityGrand Forks 
Event StateNORTH DAKOTA 
Event Country-- 
Zipcode of the event site58201 
Event Date Year2006 
Event Date Month
MidAir Collision IndicatorNo 
On Ground Collision occurred ?No 
Event Location Latitude475700N 
Event Location Longitude0971100W 
Event Location AirportGrand Forks Intl 
Event Location Nearest Airport IDGFK 
Indicates whether the acc/inc occurred off or on an airportOn Airport 
Distance from airport in statute miles-- 
Degrees magnetic from airport-- 
Airport Elevation-- 
Weather Briefing Completeness-- 
Investigator's weather sourceWeather Observation Facility 
Time of the weather observation1953 Central Daylight Time 
Direction of event from weather observation facility (degrees)-- 
Weather Observation Facility IDGFK 
Elevation of weather observation facility845 
Distance of event from weather observation facility (units?)
Time Zone of the weather observationCDT 
Lighting ConditionsDay 
Lowest Ceiling Height-- 
Lowest Non-Ceiling Height25000 
Sky/Lowest/Cloud ConditionsFew 
Sky Condition for Lowest CeilingNone 
Visibility Runway Visual Range (Feet)-- 
Visibility Runway Visual Value (Statute Miles)-- 
Visibility (Statute Miles) 10 
Air Temperature at event time (in degrees celsius)21 
Dew Point at event time (in degress fahrenheit)
Wind Direction (degrees magnetic)290 
Variable Wind IndicatorWind direction could be determined 
Wind Speed (knots)-- 
Wind Velocity Indicator -- 
Wind Gust IndicatorGusting 
Wind Gust (knots)
Altimeter Setting at event time (in. Hg) 29.91 
Density Altitude (feet)-- 
Intensity of Precipitation-- 
METAR weather report METAR KGFK 170053Z 29003KT 10SM FEW250 21/07 A2991 
Event Highest InjuryNone 
On Ground, Fatal Injuries-- 
On Ground, Minor Injuries-- 
On Ground, Serious Injuries-- 
Injury Total Fatal-- 
Injury Total Minor-- 
Injury Total None
Injury Total Serious-- 
Injury Total All-- 
Investigating Agency-- 
NTSB Docket Number (internal use)20413 
NTSB Notification SourceFAA  
NTSB Notification DateJun 19 2006 12:00AM 
NTSB Notification Time-- 
Fiche Number and/or location -used to find docket informationDMS 
Date of most recent change to recordOct 3 2006 2:46PM 
User who most recently changed recordNTSB\JOHB  
Basic weather conditionsVisual Meteorological Cond 
FAA District OfficeFAA-Fargo FSDO 
Aircraft Involved
Aircraft #1
Aircraft Registration NumberN1675U 
NTSB NumberCHI06CA168 
Missing Aircraft Indicator-- 
Federal Aviation Reg. PartPart 91: General Aviation 
Type of Flight Plan filedNone 
Flight plan Was Activated?-- 
DamageSubstantial 
Aircraft FireNone 
Aircraft ExplosionNone 
Aircraft Manufacturer's Full NameSchweizer 
Aircraft Model269C 
Aircraft Series Identifier-- 
Aircraft Serial NumberS1878 
Certified Max Gross Weight2050 
Aircraft CategoryHelicopter 
Aircraft Registration Class-- 
Aircraft is a homebuilt?No 
Flight Crew Seats-- 
Cabin Crew Seats-- 
Passenger Seats-- 
Total number of seats on the aircraft
Number of Engines
Fixed gear or retractable gearFixed 
Aircraft, Type of Last InspectionAnnual 
Date of Last InspectionMay 1 2006 12:00AM 
Airframe hours since last inspection-- 
Airframe Hours480 
ELT InstalledNo 
ELT ActivatedNo 
ELT Aided Location of Event SiteNo 
ELT Type-- 
Aircraft Owner NameUniv of North Dakota 
Aircraft Owner Street Address-- 
Aircraft Owner CityGrand Forks 
Aircraft Owner StateND 
Aircraft Owner CountryUSA  
Aircraft Owner Zipcode-- 
Operator is an individual?Yes 
Operator Name-- 
Operator Same as Owner?Yes 
Operator Is Doing Business As-- 
Operator Address Same as Owner?Yes 
Operator Street Address-- 
Operator City-- 
Operator State-- 
Operator Country-- 
Operator Zip code-- 
Operator Code-- 
Owner has at least one certificateNone 
Other Operator of large aircraft?-- 
Certified for Part 133 or 137 Operation-- 
Operator Certificate Number-- 
Indicates whether an air carrier operation was scheduled or not-- 
Indicates Domestic or International Flight-- 
Operator carrying Pax/Cargo/Mail-- 
Type of Flying (Per_Bus / Primary)Instructional 
Second Pilot on BoardYes 
Departure Point Same as EventYes 
Departure Airport CodeGFK  
Departure CityGrand Forks 
Departure StateND 
Departure CountryUSA 
Departure Time1800 
Departure Time ZoneCDT 
Destination Same as Local Fltdest & departure same, accident can occur anywhere 
Destination Airport Code-- 
Destination City-- 
Destination State-- 
Destination Country-- 
Specific Phase of FlightLanding - flare/touchdown 
Report sent to ICAO?-- 
Evacuation occurred-- 
Date of most recent change to recordJul 21 2006 5:17PM 
User who most recently changed recordDINC  
Since inspection or accidentTime of Accident 
Event Location Runway Number and LocationNA 
Runway Length-- 
Runway Width-- 
Sight Seeing flightNo 
Air Medical FlightNo 
Medical Flight--