# NTSB DEN05LA081: Robinson R22 Beta, N983KC, St. George, UT, May 19, 2005 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: May 19, 2005, 15:41 local (21:41 UTC) - Place: St. George, UT - Coordinates: 37.180438, -113.600341 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.1804&lon=-113.6003&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report October 27, 2005 - Report: Approved by Office Director - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 61564 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN05LA081 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/61564/pdf - Page: https://openairdocs.org/ntsb/DEN05LA081 ## Probable cause the pilot's improper autorotation. A contributing factor was the flight instructor's inadequate supervision of the pilot. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, maneuvering - autorotation - improper, pilot in command (cause) - supervision - inadequate, pilot in command(cfi) (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - remedial action - not successful, pilot in command(cfi) - terrain condition - ground ## Analysis The flight instructor said the student entered the autorotation and completed a 180-degree turn at an altitude of approximately 250 feet agl. There was a noticeable lateral vibration of the airframe and a rapid increase in descent rate. The instructor took control, advanced the throttle, and noticed that the rotor and engine rpm needles were "joined" just below 100 percent rpm. He said he did not understand why the helicopter had a descent rate greater than 1,500 feet per minute when the engine was at full power and rotor rpm was at 100 per cent rpm. Neither pilot heard the LOW ROTOR RPM warning. The instructor attempted to flare but there was insufficient time, and the helicopter impacted terrain and rolled over. Post-accident examination revealed no mechanical anomalies. There were dust devils in the area after the accident occurred. ## Factual narrative On May 19, 2005, at 1541 mountain daylight time, a Robinson R22 Beta, N983KC, piloted by a private pilot under the supervision of a commercial-certificated flight instructor, was substantially damaged when it collided with terrain during a practice autorotation near St. George, Utah. Visual meteorological conditions prevailed at the time of the accident. The local instructional flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot and flight instructor sustained minor injuries. The flight originated at St. George, Utah, approximately 1500. The instructor said they had been airborne approximately 45 minutes prior to the accident. During that time, they had performed three straight-in autorotations and four 180-degree autorotations, and that the aircraft and all systems were operating normally. They entered the autorotation normally and completed a 180-degree turn at an altitude of approximately 250 feet agl. There was a noticeable lateral vibration of the airframe and a rapid increase in descent rate. The instructor took control, advanced the throttle, and noticed that the rotor and engine rpm needles were "joined" just below 100 percent rpm. He said he did not understand why the helicopter had a descent rate greater than 1,500 feet per minute when the engine was at near full power and rotor rpm was almost at 100 per cent rpm. Neither pilot heard the LOW ROTOR RPM warning. The instructor attempted to flare but there was insufficient time, and the helicopter impacted terrain. The tail rotor was dragged along the ground approximately 30 feet, then the skids struck the ground and the helicopter rolled over. The tail was severed from the aircraft, the landing skids were torn off, the windscreen was shattered, and the skin was deformed. A mechanic who examined the helicopter said it appeared all systems were operating normally prior to the accident, and no mechanical anomalies were found. A witness located 1 mile north of the airport said that the day of the accident was the first day of increased dust devil/wind shear/microburst activity common to the region during the summer months. The instructor said he also noticed dust devils in the area after the accident occurred. The helicopter's rate of descent during autorotation, as reported by the pilot, was equal to the rotor downwash velocity of approximately 1500 feet per minute. The power had been at idle, but was increased at the onset of the vibration. The instructor said that the airspeed never dropped below 50 knots, and that during the autorotation, the power remained off. A spokesman for Robinson Helicopter confirmed that the translational lift velocity for this helicopter was approximately 20 knots. The FAA Rotorcraft Flying Handbook states that following conditions are linked to vortex ring state: a vertical descent of at least 300 feet per minute, the engine power setting between 20-100 percent, and a horizontal velocity slower than the effective translational lift velocity. ## Aircraft - Registration: [N983KC](https://openairdocs.org/deregistered/N983KC-2013-10-29), registration cancelled 2013-10-29, S/N 2811, built 1998 (OpenAirDocs) - Reported make and model: Robinson R22 Beta - Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 2811 - Airframe hours: 2566.7 - Engines: Lycoming 0-360-J2A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: A Flight Above - Registered owner: KNK Leasing - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, April 1, 2005, 60.4 hours before - Departed: SGU, St. George, UT - Destination: SGU - Airport: SGU, St George Municipal, runway 16, 6,606 × 100 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 27; injuries: minor; flight instructor, commercial; medical: class 2, without waivers/limitations; last flight review November 1, 2003; seat: left; flight hours: 1,686 total, 1,619 as pilot in command, 282 in the last 90 days, 91 in the last 30 days, 2 in the last 24 hours - Pilot; age 23; injuries: minor; private; medical: class 2, without waivers/limitations; last flight review February 1, 2005; seat: right; flight hours: 133 total, 84 as pilot in command, 68 in the last 90 days, 15 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 91 °F, dew point 39 °F - Altimeter: 29.92 inHg - Observed at: SGU, 8 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 (OpenAirDocs). - [Accident 20050519007939A](https://openairdocs.org/incident/20050519007939A), May 19, 2005: Robsin R22BETA, Saint George, UT, Substantial damage. (-23) Instructor pilot was demonstrating 180 autorotations to an open sod and dirt field to a termination with power. Temp was 38C, da 5100 winds south at… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.