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Location:
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Dustin, Oklahoma
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Accident Number:
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CEN21LA173
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Date & Time:
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March 26, 2021, 15:15 Local
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Registration:
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N178DF
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Aircraft: ROBINSON HELICOPTER COMPANY R44 II
Aircraft Damage: Substantial
Defining Event: Loss of control in flight Injuries: 2 Serious, 2 Minor
Flight Conducted Under: Part 91: General aviation - Aerial observation
Analysis
The pilot of the helicopter stated that, while maneuvering “low and slow” with three passengers onboard, he noticed “insufficient power” and shortly thereafter, the low rotor rpm warning annunciated. He applied full throttle and attempted to regain rotor rpm but was unsuccessful. The pilot stated that he was forced to land immediately, during which the helicopter impacted a tree then terrain, resulting in substantial damage.
The pilot reported that there were no mechanical malfunctions or failures of the helicopter and recommended operating “at a lower gross weight.” Postacccident examination of the helicopter revealed no anomalies that would have precluded normal operation.
Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot’s insufficient monitoring of the helicopter’s power while flying at low altitude and at low airspeed, which resulted in the loss of rotor rpm and impact with a tree and terrain.
Findings
Personnel issues Aircraft - Incorrect action performance - Pilot Airspeed - Not attained/maintained
Environmental issues - Tree(s) - Effect on equipment
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Factual Information
On March 26, 2021, about 1515 central daylight time, a Robinson Helicopter Company R44 II, N178DF, was substantially damaged when it was involved in an accident near Dustin, Oklahoma. The private pilot and one passenger received serious injuries, and two passengers received minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight.
The pilot stated that while maneuvering “low and slow” with three passengers onboard, he noticed “insufficient power” and shortly thereafter, the low rotor rpm warning annunciated. He applied full throttle and attempted to regain rotor rpm but was unsuccessful. The pilot stated that he was forced to land the helicopter immediately, during which the helicopter impacted a tree then terrain, resulting in substantial damage that included damage to the main rotor, fuselage, and tailboom.
The pilot reported that there were no mechanical malfunctions or failures with the helicopter, and recommended operating “at a lower gross weight.” Postacccident examination of the helicopter revealed no anomalies that would have precluded normal operation.
History of Flight
Maneuvering-low-alt flying Uncontrolled descent - Loss of control in flight (Defining event) Attempted remediation/recovery
Landing - Collision during takeoff/land
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Pilot Information
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Certificate:
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Private
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Age:
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59,Male
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Airplane Rating(s):
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Single-engine land
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Seat Occupied:
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Right
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Other Aircraft Rating(s):
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None
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Restraint Used:
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4-point
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Instrument Rating(s):
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Helicopter
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Second Pilot Present:
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No
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Instructor Rating(s):
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None
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Toxicology Performed:
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Medical Certification:
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Class 2 Without waivers/limitations
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Last FAA Medical Exam:
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March 26, 2021
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Occupational Pilot:
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No
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Last Flight Review or Equivalent:
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June 3, 2020
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Flight Time:
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3687 hours (Total, all aircraft), 1447 hours (Total, this make and model), 3552 hours (Pilot In Command, all aircraft), 124 hours (Last 90 days, all aircraft), 82 hours (Last 30 days, all aircraft), 3 hours (Last 24 hours, all aircraft)
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Aircraft and Owner/Operator Information
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Aircraft Make:
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ROBINSON HELICOPTER COMPANY
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Registration:
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N178DF
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Model/Series:
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R44 II
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Aircraft Category:
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Helicopter
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Year of Manufacture:
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2007
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Amateur Built:
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Airworthiness Certificate:
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Normal
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Serial Number:
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11969
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Landing Gear Type:
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Skid
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Seats:
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4
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Date/Type of Last Inspection:
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January 18, 2021 Annual
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Certified Max Gross Wt.:
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2500 lbs
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Time Since Last Inspection:
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Engines:
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1 Reciprocating
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Airframe Total Time:
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2347 Hrs at time of accident
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Engine Manufacturer:
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Lycoming
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ELT:
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Installed, not activated
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Engine Model/Series:
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IO-540-AE1A5
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Registered Owner:
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Rated Power:
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290
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Operator:
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Operating Certificate(s) Held:
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None
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Meteorological Information and Flight Plan
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Conditions at Accident Site:
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Visual (VMC)
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Condition of Light:
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Day
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Observation Facility, Elevation:
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OKM,720 ft msl
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Distance from Accident Site:
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90 Nautical Miles
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Observation Time:
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15:15 Local
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Direction from Accident Site:
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270°
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Lowest Cloud Condition:
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Clear
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Visibility
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10 miles
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Lowest Ceiling:
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None
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Visibility (RVR):
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Wind Speed/Gusts:
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14 knots / 21 knots
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Turbulence Type Forecast/Actual:
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/
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Wind Direction:
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150°
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Turbulence Severity Forecast/Actual:
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/
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Altimeter Setting:
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29.89 inches Hg
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Temperature/Dew Point:
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24°C / 7°C
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Precipitation and Obscuration:
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No Obscuration; No Precipitation
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Departure Point:
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Henryetta, OK (F10)
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Type of Flight Plan Filed:
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None
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Destination:
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Dustin, OK
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Type of Clearance:
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None
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Departure Time:
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13:30 Local
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Type of Airspace:
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Class G
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Wreckage and Impact Information
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Crew Injuries:
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1 Serious
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Aircraft Damage:
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Substantial
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Passenger Injuries:
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1 Serious, 2 Minor
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Aircraft Fire:
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None
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Ground Injuries:
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Aircraft Explosion:
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None
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Total Injuries:
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2 Serious, 2 Minor
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Latitude, Longitude:
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35.2707,-96.0308(est)
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Administrative Information
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Investigator In Charge (IIC):
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Gallo, Mitchell
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Additional Participating Persons:
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Renae Allmond; Federal Aviation Administration; Will Rogers Flight Standards District Office ; Oklahoma City, OK
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Original Publish Date:
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August 19, 2022 Investigation Class: 3
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Note:
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The NTSB did not travel to the scene of this accident.
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Investigation Docket:
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https://data.ntsb.gov/Docket?ProjectID=102855
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