# NTSB CEN15LA198: Robinson Helicopter R44 II, N754R, Dunlap, IL, April 15, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 15, 2015, 16:00 local (21:00 UTC) - Place: Dunlap, IL - Coordinates: 40.9225, -89.678886 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.9225&lon=-89.6789&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report November 29, 2016 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA, Robinson Helicopter - NTSB case key (mKey): 91039 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN15LA198 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91039/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91039 - Page: https://openairdocs.org/ntsb/CEN15LA198 ## Probable cause A loss of main rotor rpm for reasons that could not be determined during postaccident examinations. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Robinson Helicopter R44 II, 24 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=7640122), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) - [Terrain](https://openairdocs.org/ntsb-findings/03021000): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Robinson Helicopter R44 II, 1 case](https://openairdocs.org/ntsb-findings/03021000/cases.md?model=7640122), [All aircraft, 267 cases](https://openairdocs.org/ntsb-findings/03021000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-climb to cruise: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Robinson Helicopter R44 II, 9 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=7640122), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Autorotation: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R44 II, 95 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640122), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Landing-flare/touchdown: Roll over](https://openairdocs.org/ntsb-events/097); cases with it: [Robinson Helicopter R44 II, 14 cases](https://openairdocs.org/ntsb-events/097/sequence.md?model=7640122), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) ## Analysis The commercial pilot stated he and the passenger were conducting a helicopter flight to observe and count geese at an altitude of 300 ft above the ground at an indicated airspeed of 60 knots. The pilot increased the collective to transition to another area when he noticed an increase in engine rpm and a decrease in rotor rpm along with the illumination of a main rotor warning light. The clutch warning light did not illuminate. The pilot initiated a downwind autorotation to a plowed field. The helicopter tipped forward on its skids, the main rotor contacted the ground, and the helicopter rolled over. Although a postaccident examination of the clutch and V-belts revealed some limited component wear, and some minor anomalies to the best tension actuator were noted, no anomalies were identified with the clutch system that would have resulted in a loss of main rotor rpm. ## Factual narrative On April 15, 2015, at 1600 central daylight time, a Robinson R44II helicopter, N754R, rolled over during an off-airport precautionary landing in Dunlap, Illinois. The commercial pilot and passenger were 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 an aerial observation flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The flight originated at 1500, from the Greater Kankakee Airport (IKK), Kankakee, Illinois.The pilot stated they were observing and counting geese at an altitude of 300 feet above the ground at an indicated airspeed of 60 knots immediately before the accident. He stated he increased the collective to transition to another area when he noticed an increase in engine rpm and a decrease in rotor rpm along with a main rotor warning light. The clutch warning light did not illuminate. The pilot initiated a downwind autorotation to a plowed field. The pilot stated that due to the tailwind and forward speed, the helicopter tipped forward on its skids, the main rotor contacted the ground and the helicopter rolled over. A postaccident examination of the wreckage by a Federal Aviation Administration inspector revealed oil inside the clutch shaft at the tail rotor end of the shaft. The inspector stated there was a roughness when he rotated the sheave and there was oil residue on the forward side of the sheave. He stated they flushed small particles of magnetic chips from the sheave bearings and there was no damage to the bearing races. The clutch, V-belts, and the belt tension actuator were subsequently removed for inspection at Robinson Helicopters under NTSB supervision. The examination of the clutch revealed an excessive amount of oil was on the forward face of the sheave and around the aft yoke. The actuator support bearing rotated smoothly. A slight roughness was noted when rotating the sheave on the shaft. The bearings were flushed with solvent. Three small metallic flakes were caught in a filter. Both bearings rotated smoother, but still had areas of roughness. The sheave grooves appeared to have normal wear. Oil drained from the clutch appeared to be the correct amount with very small metallic flakes in the oil. The oil was dark, but did not smell burnt. The clutch was disassembled and a small amount of oil was observed between the aft plug and the aft yoke indicating that the plug had been leaking. Visual inspection of the sprag did not show any anomalies. The four V-belts showed wear that was consistent with the reported time in service. The belt tension actuator was bent during the accident impact. The screw tube and the left-side stack of springs were bent. The heat shrink material on both spring switches was red and blue. According to the manufacturer, black heat shrink was used at the factory. The actuator down limit screw was extended about0.4 inch and the extension was measured as 1.3 inch. The typical extension range is 0.08 inch to 1.1 inch. The actuator was placed on a test stand and the actuator functioned normally. Although there were minor anomalies noted during the examination of the clutch, V-belts, or belt tension actuator, none of the anomalies would have prevented the normal operation of the clutch system. ## Aircraft - Registration: [N754R](https://openairdocs.org/aircraft/N754R), registered now, S/N 11318, built 2006 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER COMPANY R44 II (II) - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540-AE1A5](https://openairdocs.org/engine/lycoming-io-540-ae1a5) (registry code 41899, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 11318 - Year built: 2006 - Engines: LYCOMING IO-540-AE1A5 205 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 5, 2015 - Departed: IKK, Kankakee, IL - Destination: C15, Pekin, IL - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane, helicopter; medical: class 2, with waivers/limitations; last flight review March 30, 2014; seat: right; restraint: 3-point; flight hours: 4,175 total, 182 in this make and model, 4,000 as pilot in command, 55 in the last 90 days, 50 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 17 knots, gusting 25 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 28 °F - Altimeter: 30.06 inHg - Observed at: PIA, 5 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 20150415005459A](https://openairdocs.org/incident/20150415005459A), Apr 15, 2015: Robinson Helicopter Company R44 II, Dunlap, IL, Substantial damage. Pilot in command reported that while flying approximately 300' AGL, the low rotor warning light came on. Engine RPM went up slightly and main rotor RPM started… ## Docket (7 files) The files NTSB released with the investigation on September 6, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91039. 8.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444222&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Pilot Statement (item 2, .PDF, 97 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444223&FileExtension=.PDF&FileName=Pilot%20Statement-Master.PDF - Component Examination (item 3, .PDF, 11 photos, 4.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444224&FileExtension=.PDF&FileName=Component%20Examination-Master.PDF - Logbook Entries (item 4, .PDF, 644 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444225&FileExtension=.PDF&FileName=Logbook%20Entries-Master.PDF - Component Information (item 5, .PDF, 343 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444226&FileExtension=.PDF&FileName=Component%20Information-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 91 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444227&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Photo Array (item 7, .PDF, 2 photos, 738 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444228&FileExtension=.PDF&FileName=Photo%20Array-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.