# NTSB DEN04LA142: Robinson R22, N777UH, Spanish Fork, UT, September 14, 2004 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: September 14, 2004, 16:20 local (22:20 UTC) - Place: Spanish Fork, UT - Coordinates: 40.02074, -111.550361 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.0207&lon=-111.5504&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor, 1 uninjured - Status: Completed, report February 24, 2005 - Report: Approved by Office Director - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 60159 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN04LA142 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/60159/pdf - Page: https://openairdocs.org/ntsb/DEN04LA142 ## Probable cause the instructor's premature flare, resulting in a hard landing, and his failure to align the helicopter with the direction of travel, resulting in a rollover.Contributing factors were the low rotor RPM and inadequate airspeed. The reason for the loss of engine power was not determined. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, approach - vfr pattern - final approach - reason for occurrence undetermined - Forced landing, descent - emergency - autorotation - Hard landing, landing - flare/touchdown - rotor rpm - inadequate, dual student (contributing factor) - airspeed - inadequate, dual student (contributing factor) - flare - not maintained, pilot in command(cfi) (cause) - proper alignment - not maintained, pilot in command(cfi) (cause) ## Analysis The helicopter was at 6,000 feet, flying at 70 knots, and exiting a canyon about 5 miles east of the airport. It was on a long final approach to runway 30. After performing pre-landing checks that included warning lights extinguished, rotor and engine tachometers and other pertinent instruments in the green arc, and carburetor heat outside the yellow arc, the instructor "pulled the carb[uretor heat] up a little, and then...pushed the trim in to prepare for landing." Shortly thereafter, the engine lost power. The collective control was lowered and the instructor took control of the helicopter. The LOW RPM light illuminated and the warning horn sounded. The instructor noticed the tachometer was "in the green" and manifold pressure (MAP) was in the red (25 inches) arc. He attempted an autorotation into an open field. He flared and the helicopter landed hard "with a slight nose right yaw." The helicopter bounced once, and then rolled over on its right side. The tail boom and tail rotor were severed. The engine was later functionally tested to full power. Nothing was found that would have been causal to the power loss. Temperature and dew point conditions were not conducive to carburetor icing. ## Factual narrative On September 14, 2004, approximately 1620 mountain daylight time, a Robinson R22, N777UH, piloted by a private pilot, sustained substantial damage during an autorotation to an open field following a loss of engine power near Spanish Fork, 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 flight instructor sustained minor injuries, and the pilot receiving instruction was not injured. The flight originated at Mt. Pleasant (43U), Utah, approximately 1615. According to the flight instructor's written statement and telephone interview, the helicopter was at 6,000 feet, flying at 70 knots, and exiting Spanish Fork Canyon. The helicopter was about 5 miles east of the Spanish Fork-Springville Airport (U77) on a long final approach to runway 30. After performing pre-landing checks that included warning lights extinguished, rotor and engine tachometers and other pertinent instruments in the green arc, and carburetor heat outside the yellow arc, the instructor "pulled the carb[uretor heat] up a little, and then...pushed the trim in to prepare for landing." Shortly thereafter, the engine lost power. The collective control was lowered and the instructor took control of the helicopter. The LOW RPM light illuminated and the warning horn sounded. The instructor noticed the tachometer was "in the green" and manifold pressure (MAP) was in the red (25 inches) arc. He attempted an autorotation into an open field. He flared and the helicopter landed hard "with a slight nose right yaw." The helicopter bounced once, and then rolled over on its right side. The tail boom and tail rotor were severed. According to the pilot's written statement, the helicopter yawed "hard to the left" when the engine lost power. He also noticed MAP was in the red arc, approximately 25-26 inches, and "there was no engine sound whatsoever." When the instructor flared for landing, the helicopter yawed slightly to the left. Forward speed and ground contact angle, however, caused the helicopter to roll over on its right side. The next day, the helicopter was trucked to the Robinson factory in Torrance, California, where, on October 1, 2004, the engine was functionally tested to full power. According to Robinson Helicopter and Textron Lycoming, nothing was found that would have been causal to the power loss. In an electronic mailing between NTSB's investigator-in-charge and the FAA Long Beach office, the question as to whether carburetor ice was raised. Robinson Helicopter's accident investigator didn't think so, citing the large temperature-dew point spread. The following are excerpts from the Robinson R22 "Pilot's Operating Handbook: "CAUTION. The R22 has a light, low-inertia rotor system. Most of the energy required for an autorotation is stored in the forward momentum of the aircraft, not in the rotor. Therefore, a well-timed cyclic flare is required and rotor RPM must be kept in the green until just before ground contact. "CAUTION. During simulated engine failures, a rapid decrease in rotor RPM will occur, requiring immediate lowering of collective control to avoid dangerously low rotor RPM. Catastrophic rotor stall could occur if the rotor RPM ever drops below 80 percent plus 1 percent per 1000 feet of altitude." ## Aircraft - Registration: [N777UH](https://openairdocs.org/aircraft/N777UH), registered now, S/N 3548, built 2004 (OpenAirDocs) - Reported make and model: Robinson R22 - Registry model: [Robinson Helicopter R22](https://openairdocs.org/model/robinson-helicopter-r22) (registry code 7640102) (OpenAirDocs) - Registry engine: [Lycoming O-360 series](https://openairdocs.org/engine/lycoming-o-360-series) (registry code 41575, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 3548 - Airframe hours: 647 - Engines: Lycoming O-360-J2A 145 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Universal Helicopters, Inc. - Airworthiness certificate: Standard, Normal - Departed: 43U, Mt. Pleasant, UT - Destination: U77, Spanish Fork, UT ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 34; injuries: minor; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; last flight review July 31, 2004; seat: right; flight hours: 167 in this make and model - Pilot; age 31; injuries: none; private; medical: class 2, valid medical--no waivers/lim.; last flight review June 30, 2003; seat: left; flight hours: 99 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 330° at 19 knots, gusting 24 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 64 °F, dew point 34 °F - Altimeter: 29.98 inHg - Observed at: PVU, 6 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 20040914021889A](https://openairdocs.org/incident/20040914021889A), Sep 14, 2004: Robsin R22, Spanish Fork, UT, Substantial damage. (-23) On sept 14, 2004 at 1604 MDT, a Robinson R-22-22 helicopter, N777UH, s/n 3548, owned by universal helicopters inc scottsdale AZ crashed in a hay field 5… ## Other investigations on N777UH (1) 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. - [NTSB DEN05LA130](https://openairdocs.org/ntsb/DEN05LA130), Aug 25, 2005: Robinson R22 (N777UH), Falcon, CO, substantial damage. Probable cause: the pilot's failure to maintain control of the helicopter while conducting a hovering maneuver. 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.