# NTSB CEN19FA009: Robinson R22, N923SH, Fulton, MO, October 17, 2018 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 2 · Field · Final report - Date: October 17, 2018, 14:21 local (19:21 UTC) - Place: Fulton, MO - Coordinates: 38.85889, -91.909446 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.8589&lon=-91.9094&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Fuel related](https://openairdocs.org/ntsb-events/190) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed - Report: Approved by Office Director - Investigation class: Class 2 - NTSB office: Central Region - Parties: Lycoming Engines, FAA FSDO, Robinson Helicopters - NTSB case key (mKey): 98512 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN19FA009 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/98512/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=98512 - Page: https://openairdocs.org/ntsb/CEN19FA009 ## Probable cause A total loss of engine power due to carburetor icing, the pilot's delayed application of carburetor heat, and the pilot's delay in entering an autorotation following the loss of engine power, which resulted in a main rotor stall due to low rotor rpm and an uncontrolled descent into terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Action: delayed action](https://openairdocs.org/ntsb-findings/02041025): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Robinson Helicopter R22 BETA, 35 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md?model=7640110), [All aircraft, 894 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md) - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Robinson Helicopter R22 BETA, 9 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=7640110), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md) - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Response/compensation (probable cause); cases with it: [Robinson Helicopter R22 BETA, 9 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=7640110), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md) - [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R22 BETA, 37 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=7640110), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Fuel related](https://openairdocs.org/ntsb-events/190) (defining event); cases with it: [Robinson Helicopter R22 BETA, 5 cases](https://openairdocs.org/ntsb-events/190/sequence.md?model=7640110), [All aircraft, 361 cases](https://openairdocs.org/ntsb-events/190/sequence.md) - [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Robinson Helicopter R22 BETA, 18 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=7640110), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Maneuvering: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Robinson Helicopter R22 BETA, 67 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=7640110), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) ## Analysis The pilot was conducting a solo cross-country flight in the helicopter as part of his instruction to obtain his rotorcraft rating. The intent of the flight was to fly solo cross-country to perform touch and go landings at another airport. About 36 minutes after departing on the flight, the helicopter impacted terrain. One witness reported that he saw the helicopter flying and heard the engine stop. He stated that the helicopter began to lose altitude and began to spin in a downward spiral. Another witness reported that he observed the helicopter flying toward him with its nose pointed downward about 45°. He stated that the blades were turning slowly and that the helicopter was making a circular motion along its axis, but not a spiral, as it flew toward the ground. The helicopter impacted terrain in a nose-low, left-skid-down attitude. Examination of the airframe and engine did not reveal any mechanical pre-impact anomalies. The main rotor blade damage was consistent with low rotor rpm at the time of impact, and the low rotor rpm caution light filament was stretched, consistent with the light being illuminated at the time of impact. Examination of the rotating engine components did not reveal any evidence consistent with rotation at the time of impact. The carburetor heat control in the cockpit was found unlocked and found in the "on" position. According to a carburetor icing probability chart, the atmospheric conditions about the time of the accident were conducive to moderate icing at cruise power settings and serious icing at descent power settings. Thus, it is likely that the helicopter experienced a loss of engine power due to carburetor ice accumulation. Although the carburetor heat was found in the on position, it is likely that the pilot applied the carburetor heat to address the loss of engine power but it was too late and at too low an altitude to restore engine power. Following the loss of engine power, the main rotor rpm would have rapidly begun to deteriorate unless the pilot immediately reduced collective and entered an autorotation. Given the signatures of low rotor rpm present at the site, it is likely that the pilot failed to initiate the autorotation in a timely manner, which allowed the main rotor rpm to deteriorate to the extent that the main rotor stalled and the pilot would be unable to recover. ## Factual narrative According to information provided by the operator, the helicopter departed Moscow Mills with 28 gallons of fuel onboard. Information published by the manufacturer indicated that the helicopter consumed between 7 and 10 gallons of fuel per hour. On October 17, 2018, about 1421 central daylight time, a Robinson R22 Beta helicopter, N923SH, was destroyed when it was involved in an accident near Fulton, Missouri. The pilot was fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 solo instructional flight. According to the operator, the pilot had been receiving instruction toward his rotorcraft-helicopter rating. The intent of the flight was to fly solo from Moscow Mills, Missouri, to Columbia Regional Airport (COU), Columbia, Missouri, and perform touch-and-go landings at COU. The helicopter departed Moscow Mills about 1345 and impacted terrain about 36 minutes later while on a direct route to COU. One witness reported that he saw the helicopter flying and heard the engine stop. He stated that the helicopter began to lose altitude and spin in a downward spiral. Another witness reported that he observed the helicopter flying toward him with its nose pointed downward about 45°. He stated that the blades were turning slowly and that the helicopter was making a circular motion along its axis, but not a spiral, as it flew toward the ground. There were no distress calls from the pilot and no radar information was available for the flight. The Boone/Callaway County Medical Examiner's Office, Columbia, Missouri, performed an autopsy of the pilot. The pilot's cause of death was multiple blunt force injuries. No significant natural disease was noted. The FAA's Forensic Sciences Laboratory performed toxicology testing on the pilot's tissue samples. The toxicology tests were negative for drugs and ethanol. ADDITIONAL INFORMATION Robinson Helicopter Company Safety Notice SN-24, "Low RPM Rotor Stall Can Be Fatal," stated: Rotor stall is very similar to the stall of an airplane wings at low airspeeds. As the airspeed of an airplane gets lower…the angle of attack of the wing must be higher for the wing to produce the lift required to support the weight of the airplane…The same thing happens during rotor stall with a helicopter except it occurs due to low rotor RPM instead of low airspeed. As the RPM of the rotor gets lower, the angle of attack of the rotor blades must be higher to generate the lift required to support the weight of the helicopter…Even if the collective is not raised by the pilot to provide the higher blade angle, the helicopter will start to descend until the upward movement of air to the rotor provides the necessary increase in blade angle of attack…The increased drag on the blades acts like a huge rotor brake causing the rotor RPM to rapidly decrease, further increasing the rotor stall. As the helicopter begins to fall, the upward rushing air continues to increase the angle of attack on theslowly-rotating blades, making recovery virtually impossible, even with full down collective. According to a carburetor icing probability chart, the atmospheric conditions were conducive to moderate icing at cruise power settings and serious icing at descent power settings. The pilot had a rotorcraft endorsement for solo flight in the R22 helicopter. The helicopter wreckage was found in a grassy area in a slight depression in the Potowatami recreational area near Fulton, MO. Initial examination of the wreckage at the accident site showed evidence that the helicopter impacted in a nose-low, left-skid-down attitude. Most of the helicopter wreckage was found resting on its left side, in a 6-foot-wide, 2-foot-deep crater. Portions of the wreckage were partially embedded in the dirt. All components were identified at the accident site, with small pieces of debris and plexiglass from the windscreen located within 30 ft of the main wreckage. Damage to the main rotor blades was consistent with low rotor rpm at the time of impact. The low rotor rpm annunciator light was examined with a 10x magnifier and showed stretched filaments consistent with it being illuminated at the time of impact. Examination of the airframe components, flight controls, and main and tail rotor drive systems did not reveal any mechanical pre-impact anomalies. The carburetor heat control in the cockpit was unlocked and bent flush with the console about 1 inch up (in the "on" position). The carburetor heat slider valve was about 1.4-inches open at the carburetor. The main fuel tank was severely impact-damaged and ruptured. A small amount of fuel was present in the auxiliary tank. The carburetor was disassembled, and the float bowls were wet but contained no fuel. The engine was successfully rotated from the crankshaft to the gearbox. Thumb compression was confirmed on all four cylinders. Engine continuity was confirmed from the crankshaft to the engine accessory gears to the fan. The dowel pin (locator pin) on the crankshaft gear was not sheared. There were both imprint marks and score marks on the oil cooler from the starter ring gears. The score marks were slightly angled and aft of the imprint marks. There were imprints on the cooling panels adjacent to the ring gear on the engine right (aircraft left side). There was no evidence of contact between the alternator fan and the engine, and no evidence of rotational scoring marks on the fan or fan scroll. There was a dent on the left side of the upper frames adjacent to the upper sheave, but no evidence of rotational scoring. No mechanical pre-impact anomalies were observed during the engine examination. ## Aircraft - Registration: [N923SH](https://openairdocs.org/deregistered/N923SH-2021-07-31), registration cancelled 2021-07-31, S/N 3864, built 2005 (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-360-J2A](https://openairdocs.org/engine/lycoming-o-360-j2a) (registry code 42314, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 3864 - Year built: 2005 - Airframe hours: 6455.8 - Engines: Lycoming O-360-J2A 145 horsepower reciprocating - Damage: Destroyed - Flight: Instructional, Part 91 - Operator: HeliSat LLC - Registered owner: Spitzer Helicopter Llc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 8, 2018 - Departed: None, Moscow Mills, MO - Destination: COU, Columbia, MO - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; injuries: fatal; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review October 16, 2017; seat: right; restraint: 3-point; toxicology performed; flight hours: 638 total, 77 in this make and model, 36 in the last 90 days, 9 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 330° at 14 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 64 °F, dew point 36 °F - Altimeter: 30.42 inHg - Observed at: COU, 14 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 20181017020199A](https://openairdocs.org/incident/20181017020199A), Oct 17, 2018: Robinson Helicopter R22 BETA, Fulton, MO, Destroyed, 1 fatal. The student pilot departed a private heliport near moscow mills, MO, enroute to the columbia regional airport (cou). While enroute near Fulton, MO, the… ## Docket (9 files) The files NTSB released with the investigation on October 9, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=98512. 170 MB in all. - NTSB form 6120 pilot operator report CEN19FA009 (item 1, PDF, 9 pages, 573 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9648197&FileExtension=pdf&FileName=NTSB%20Form%206120%20Pilot%20Operator%20Report%20CEN19FA009_Redacted-Rel.pdf - Callaway county sheriff report (item 2, PDF, 9 pages, 41 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9648546&FileExtension=pdf&FileName=Callaway%20County%20Sheriff%20Report_Redacted-Rel.pdf - Excerpt from published R22B specifications and fuel consumption CEN19FA009 (item 3, PDF, 1 page, 301 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9648555&FileExtension=pdf&FileName=Excerpt%20from%20Published%20R22B%20Specifications%20and%20Fuel%20Consumption%20CEN19FA009-Rel.pdf - Memorandum for the record airframe examinations findings CEN19FA009 (item 4, PDF, 4 pages, 186 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9648425&FileExtension=pdf&FileName=Memorandum%20for%20the%20Record%20Airframe%20Examinations%20Findings%20CEN19FA009_Redacted-Rel.pdf - Memorandum for the record carburetor icing probability CEN19FA009 (item 5, PDF, 1 page, 255 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9648564&FileExtension=pdf&FileName=Memorandum%20for%20the%20Record%20Carburetor%20Icing%20Probability%20CEN19FA009_Redacted-Rel.pdf - Memorandum for the record engine examination findings CEN19FA009 (item 6, PDF, 1 page, 176 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9649029&FileExtension=pdf&FileName=Memorandum%20for%20the%20Record%20Engine%20Examination%20Findings%20CEN19FA009_Redacted-Rel.pdf - Memorandum for the record witness diagram and statements CEN19FA009 (item 7, PDF, 3 pages, 557 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9649069&FileExtension=pdf&FileName=Memorandum%20for%20the%20Record%20Witness%20Diagram%20and%20Statements%20CEN19FA009_Redacted-Rel.pdf - Pilot flight records (item 8, PDF, 38 pages, 168 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9649440&FileExtension=pdf&FileName=Pilot%20Flight%20Records_Redacted-Rel.pdf - Toxicology report CEN19FA009 (item 9, PDF, 1 page, 171 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9649259&FileExtension=pdf&FileName=Toxicology%20Report%20CEN19FA009_Redacted-Rel.pdf From the NTSB's public API. 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