# NTSB CEN12LA230: Robinson Helicopter R22 Beta, N104MH, Isabel, SD, April 5, 2012 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: April 5, 2012, 07:00 local (13:00 UTC) - Place: Isabel, SD - Coordinates: 45.267223, -101.38639 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.2672&lon=-101.3864&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Serious injuries - Injuries: 1 serious, 1 uninjured - Status: Completed, report December 5, 2013 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Rapid City FSDO - SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs) - NTSB case key (mKey): 83307 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12LA230 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83307/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83307 - Page: https://openairdocs.org/ntsb/CEN12LA230 ## Probable cause The partial loss of engine power due to carburetor ice. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Contributed to outcome (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) - [Aircraft](https://openairdocs.org/ntsb-findings/01050000): Aircraft › Aircraft power plant · Not specified (probable cause); cases with it: [Robinson Helicopter R22 BETA, 2 cases](https://openairdocs.org/ntsb-findings/01050000/cases.md?model=7640110), [All aircraft, 151 cases](https://openairdocs.org/ntsb-findings/01050000/cases.md) - [Action: lack of action](https://openairdocs.org/ntsb-findings/02041030): Personnel issues › Action/decision · Pilot; cases with it: [Robinson Helicopter R22 BETA, 16 cases](https://openairdocs.org/ntsb-findings/02041030/cases.md?model=7640110), [All aircraft, 792 cases](https://openairdocs.org/ntsb-findings/02041030/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Miscellaneous/other](https://openairdocs.org/ntsb-events/900); cases with it: [Robinson Helicopter R22 BETA, 24 cases](https://openairdocs.org/ntsb-events/900/sequence.md?model=7640110), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Maneuvering-low-alt flying: Abrupt maneuver](https://openairdocs.org/ntsb-events/270); cases with it: [Robinson Helicopter R22 BETA, 11 cases](https://openairdocs.org/ntsb-events/270/sequence.md?model=7640110), [All aircraft, 346 cases](https://openairdocs.org/ntsb-events/270/sequence.md) - [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Robinson Helicopter R22 BETA, 11 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=7640110), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Maneuvering-low-alt flying: 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) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R22 BETA, 85 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640110), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Post-impact: Roll over](https://openairdocs.org/ntsb-events/097); cases with it: [Robinson Helicopter R22 BETA, 21 cases](https://openairdocs.org/ntsb-events/097/sequence.md?model=7640110), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) - [Post-impact: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Robinson Helicopter R22 BETA, 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=7640110), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis While maneuvering at low altitude during a coyote hunting operation, the helicopter experienced a partial loss of engine power. The helicopter descended, impacted trees and terrain, and rolled on its right side. There was a minor fuel leak but no postimpact fire. A postaccident examination of the helicopter did not reveal any evidence of preimpact mechanical malfunction or failures that would have precluded normal operation. Based on the temperature and dew point about the time of the accident, the conditions were conducive to serious carburetor icing at any power setting. The pilot reported that he was unsure if he had used carburetor heat for the accident flight. Available evidence suggests that the engine partially lost power in the absence of carburetor heat while operating in conditions conducive to carburetor icing. ## Factual narrative On April 5, 2012, about 0700 mountain daylight time, a Robinson R22 Beta helicopter, N104MH, impacted terrain while maneuvering at low altitude near Isabel, South Dakota. The pilot was seriously injured and the passenger was not injured. The helicopter was substantially damaged. The helicopter was registered to and operated by the pilot, under the provisions of 14 Code of Federal Regulations Part 91, as a coyote hunting flight. Day visual meteorological conditions prevailed and no flight plan was filed. The flight departed Timber Lake Municipal Airport (D58), Timber Lake, South Dakota about 0630 for the local flight. The pilot reported that he was flying about 50 to 70 knots southbound about 50 feet or more above ground level (AGL) with the surface wind out of the southeast. He made a sudden steep right turn to the west to intercept a coyote when he felt a loss of engine power, heard a "low rotor horn", and he immediately "dumped the collective". The helicopter impacted trees and terrain and rolled on its right side. There was a minor fuel leak, but no postimpact fire. After the helicopter came to rest both occupants were able to extract themselves from the wreckage. The injured pilot stayed with the wreckage while the passenger walked several miles in the remote rural area to a residence to make a telephone call to 9-1-1 emergency. A postaccident examination of the helicopter showed an adequate amount of uncontaminated fuel was present. The tips of the main rotor blades were curved up almost 90 degrees up from the horizontal. There was little evidence of rotational impact damage on the leading edges of the main rotor blades and tail rotor blades. No preimpact anomalies were found which would have prevented normal operation. The nearest aviation weather reporting station was located at Mobridge Municipal Airport (KMBG), Mobridge, South Dakota, about 44 miles northeast from the accident site. At 0652, the KMBG automated surface observing system reported the following weather conditions: wind 130 degrees at 11 knots, visibility 10 miles, few clouds at 3,900 feet AGL, temperature 7 degrees Celsius, dew point minus 1 degree Celsius, and an altimeter setting of 29.87 inches of Mercury. A weather reporting station was located at Timber Lake, South Dakota, about 15 miles northeast from the accident site. At 0700 the Timber Lake reporting station reported an average temperature of 37 degrees Fahrenheit, and an average humidity of 71 percent. The wind was reported as 8 miles per hour gusting to 15 miles per hour from 133 degrees. The carburetor icing probability chart included in Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin No. CE-09-35, Carburetor Icing Prevention, indicates that an aircraft operating in the ambient conditions at the time of the accident could expect a serious risk of accumulating carburetor ice at any power setting. The FAA Pilot's Handbook of Aeronautical Knowledge states that when conditions areconductive to carburetor icing that carburetor heat should be applied immediately and should be left on until the pilot is certain all the ice has been removed. Additionally, if ice is present the application of partial carburetor heat or leaving heat on for an insufficient time might aggravate the situation. The pilot reported that he was unsure if he had used carburetor heat for the accident flight. ## Aircraft - Registration: [N104MH](https://openairdocs.org/deregistered/N104MH-2016-01-12), registration cancelled 2016-01-12, S/N 1843, built 1991 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER R22 BETA - Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 1843 - Airframe hours: 6197 - Engines: LYCOMING 0-320 SERIES 131 horsepower reciprocating - Damage: Substantial damage - Flight: Other work use, Part 91 - Operator: Duane J Kraft, doing business as Air Kraft Spraying - Registered owner: Duane J Kraft - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 1, 2012, 13 hours before - Departed: D58, Timber Lake, SD - Destination: D58, Timber Lake, SD ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; injuries: serious; commercial; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review April 30, 2011; seat: right; restraint: 3-point; flight hours: 11,690 total, 208 in this make and model, 40 in the last 90 days, 20 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 11 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 45 °F, dew point 30 °F - Altimeter: 29.87 inHg - Observed at: KMBG, 44 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 20120405007179A](https://openairdocs.org/incident/20120405007179A), Apr 5, 2012: Robinson Helicopter R22 BETA, Isabel, SD, Substantial damage. On April 5, 2012 at 6:45AM a Robinson R-22 N104MH [privacy data omitted] of air kraft sprayers timber lake, SD, was in cruise flight during predator control… ## Docket (5 files) The files NTSB released with the investigation on September 26, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83307. 8.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40366624&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - IIC's Summary of Findings (item 2, .PDF, 89 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401544&FileExtension=.PDF&FileName=IIC%27s%20Summary%20of%20Findings-Master.PDF - Report of Operator's Fuel Quality Inspection (item 3, .PDF, 1 photo, 298 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401545&FileExtension=.PDF&FileName=Report%20of%20Operator%27s%20Fuel%20Quality%20Inspection-Master.PDF - Weather Summary (item 4, .PDF, 827 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40366625&FileExtension=.PDF&FileName=Weather%20Summary-Master.PDF - Photo (item 5, .PDF, 4.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40401546&FileExtension=.PDF&FileName=Photo-Master.PDF 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.