# NTSB CEN22LA323: Bell 206B, N6BU, Verona, IL, July 18, 2022 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 18, 2022, 18:49 local (23:49 UTC) - Place: Verona, IL · 4.8 mi south of Verona - Coordinates: 41.199351, -88.502097 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.1994&lon=-88.5021&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: TSB Canada, Rolls Royce, FAA - NTSB case key (mKey): 105514 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN22LA323 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105514/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105514 - Page: https://openairdocs.org/ntsb/CEN22LA323 ## Probable cause A loss of rotor rpm for reasons that could not be determined. ## 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: [Bell 206B, 9 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=1181511), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) (defining event); cases with it: [Bell 206B, 5 cases](https://openairdocs.org/ntsb-events/000/sequence.md?model=1181511), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) ## Analysis Before departure, the helicopter was loaded with about 30 gallons of fuel and 80 gallons of spray product. After takeoff from a load truck, the pilot received a low rotor alarm and the helicopter began to sink. He performed an autorotation and the helicopter bounced upon landing. The tailboom was severed by the main rotor blades which resulted in substantial damage. During a postaccident examination and engine test run, no anomalies were noted that would have precluded normal operation. The reason for the loss of rotor rpm could not be determined based on the available evidence. ## Factual narrative On July 18, 2022, about 1849 central daylight time, a Bell 206B3 helicopter, N6BU, sustained substantial damage when it was involved in an accident near Verona, Illinois. The pilot was uninjured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The pilot reported that this was not the first flight of the day and, before departure, he had about 30 gallons of fuel and 80 gallons of spray product. After takeoff from a load truck, he received a low rotor alarm and the helicopter began to sink. He performed an autorotation and the helicopter bounced upon landing. The tailboom was severed by the main rotor blades which resulted in substantial damage. During a postaccident examination, the engine N1 system turned freely and was continuous from the compressor to the starter generator. The engine N2 system turned and was connected to the powertrain. No foreign object damage was noted on the first stage compressor blades or compressor inlet, and the inlet particle separator system was intact and was not blocked. The fourth stage turbine wheel was normal in appearance when viewed from the exhaust collector. Linkages from the collective to the Power Turbine Governor (PTG) and from the throttle twist grip to the Fuel Control Unit (FCU) were secure. The FCU throttle input lever was rigged appropriately and contacted the minimum and maximum stops when the throttle was rotated to the cut off and fly positions respectively. The PTG rotated through about 20° (from 60 to 80 on the indicator) when the collective was moved from full down to full up. Helicopter electrical power was switched on, and no engine chip lights were noted. The fuel quantity gage indicated 30 gallons. The fuel boost pumps were individually tested, and fuel flowed freely from both. The engine was removed from the airframe and subsequently placed on a test stand. The engine started, idled, and accelerated as designed during the testing with no flame outs or uncommanded power fluctuations noted. No anomalies were observed during the exam or testing that would have precluded normal operation. ## Aircraft - Registration: [N6BU](https://openairdocs.org/aircraft/N6BU), registered now, S/N 4034, built 1988 (OpenAirDocs) - Reported make and model: BELL 206B - Registry model: [Bell 206B](https://openairdocs.org/model/bell-206b) (registry code 1181511) (OpenAirDocs) - Registry engine: [Allison 250-C20](https://openairdocs.org/engine/allison-250-c20) (registry code 03080, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 4034 - Year built: 1988 - Engines: Allison 250-C20 turbo shaft - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Top Gun Precision Ag LLC - Registered owner: Top Gun Precision Ag LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 1, 2021 ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; injuries: none; commercial; medical: class 2, without waivers/limitations; last flight review May 28, 2022; seat: right; restraint: 5-point; flight hours: 3,400 total, 200 in this make and model, 3,200 as pilot in command, 100 in the last 90 days, 50 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 290° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 70 °F - Altimeter: 29.88 inHg - Observed at: KC09, 14 nm away - METAR: KC09 182335Z AUTO 29004KT 10SM CLR 29/21 A2988 RMK AO2 T02850207 ## 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 20220718007789A](https://openairdocs.org/incident/20220718007789A), Jul 18, 2022: Bell 206B, Verona, IL, Substantial damage. At approximately 1900 local time (0000Z) on July 18, 2022, a Bell 206B helicopter, serial number 4034, [privacy data omitted] departed from an agricultural… ## Docket (7 files) The files NTSB released with the investigation on October 25, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105514. 14.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 7 pages, 7.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14787883&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Pilot's statement (item 2, PDF, 1 page, 63 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14788353&FileExtension=pdf&FileName=PIC%20ROC-Rel.pdf - Photos (item 3, PDF, 1 page, 128 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14788508&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf - Maintenance records (item 4, PDF, 6 pages, 5.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14788207&FileExtension=pdf&FileName=Maintenance%20Records_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation (item 5, PDF, 1 page, 676 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14788927&FileExtension=pdf&FileName=NTSB%20Party%20Form_Redacted-Rel.pdf - Rolls royce field notes (item 6, PDF, 3 pages, 132 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14789607&FileExtension=pdf&FileName=Rolls-Royce%20Field%20Notes%20N6BU_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 7, PDF, 1 page, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14827442&FileExtension=pdf&FileName=Signed%20Wreckage%20Release_Redacted-Rel.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.