# NTSB WPR12CA236: Bell 206B, N106TV, Burbank, WA, May 30, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: May 30, 2012, 07:10 local (14:10 UTC) - Place: Burbank, WA - Coordinates: 46.207778, -118.956947 - Nearby events: https://openairdocs.org/map.md?lat=46.2078&lon=-118.9569&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 15, 2012 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 83795 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR12CA236 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83795/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83795 - Page: https://openairdocs.org/ntsb/WPR12CA236 ## Probable cause The failure of maintenance personnel to properly torque an air tube fitting, which resulted in a total loss of engine power. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine fuel and control: fuel controlling system](https://openairdocs.org/ntsb-findings/01057320): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Bell 206B, 2 cases](https://openairdocs.org/ntsb-findings/01057320/cases.md?model=1181511), [All aircraft, 59 cases](https://openairdocs.org/ntsb-findings/01057320/cases.md) - [Action: forgotten action/omission](https://openairdocs.org/ntsb-findings/02041035): Personnel issues › Action/decision · Maintenance personnel (probable cause); cases with it: [Bell 206B, 4 cases](https://openairdocs.org/ntsb-findings/02041035/cases.md?model=1181511), [All aircraft, 440 cases](https://openairdocs.org/ntsb-findings/02041035/cases.md) - [Misc hardware: hoses and tubes](https://openairdocs.org/ntsb-findings/01071410): Aircraft › Fluids/misc hardware · Incorrect service/maintenance (probable cause); cases with it: [Bell 206B, 1 case](https://openairdocs.org/ntsb-findings/01071410/cases.md?model=1181511), [All aircraft, 40 cases](https://openairdocs.org/ntsb-findings/01071410/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Bell 206B, 17 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=1181511), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Autorotation: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Bell 206B, 57 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1181511), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis During an aerial application flight, the single engine helicopter was flying low over an apple orchard when the engine began to lose power. The pilot decreased his airspeed toward zero and performed a hovering autorotation into the orchard. During the landing, the rotor blades impacted the trees, and the tail boom separated from the main fuselage. An examination of the engine revealed that the compressor discharge pressure (PC) air tube, which connected the PC air filter to the power turbine governor was disconnected. The “B” nut that connected the tube to the PC air filter was present on the tube but not threaded onto the PC air filter boss. The threads on both the PC air filter boss and the “B” nut did not exhibit any damage or abnormalities. Review of the maintenance records showed that, about 6 hours before the accident, the turbine assembly and bleed valve had been replaced. Removal and reinstallation of the PC air tube was conducted as part of the documented maintenance. It is likely that maintenance personnel did not properly torque the “B” nut when reinstalling the tube and the loose “B” nut backed off in-flight. According to the engine manufacturer's technical representative, disconnection of the PC air tube during engine operation would result in a loss of engine power. ## Factual narrative The pilot stated that as he was flying low over the apple orchard and rolled out of a turn, the engine began to lose power, which was accompanied by the engine out horn and light. He decreased his airspeed towards zero, and performed a hovering autorotation into the orchard. During the landing the rotor blades impacted the trees and the tail boom separated from the main fuselage. An examination of the engine revealed that Pc air tube that connects the Pc air filter to to the Power Turbine Governor (PTG) was disconnected. The b-nut that connects the tube to the Pc air filter was present on the tube but not threaded onto the Pc air filter boss. Review of the maintenance records showed that about 6 hours prior to the accident the turbine assembly and bleed valve had been replaced. The threads on both the Pc air filter and b-nut did not exhibit any damage or abnormalities. The removal and reinstallation of the Pc air tube was conducted as part of the documented maintenance. According to the engine manufacturer's technical representative, the disconnection of the Pc air tube during engine operation would result in a loss of engine power. ## Aircraft - Registration: [N106TV](https://openairdocs.org/deregistered/N106TV-2018-02-09), registration cancelled 2018-02-09, S/N 2783, built 1979 (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 SER 250HP](https://openairdocs.org/engine/allison-250-ser-250hp) (registry code 03002, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 2783 - Airframe hours: 11900 - Engines: Rolls Royce 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: J.R. Helicopters Leasing LLC - Registered owner: J.R. Helicopters Leasing LLC - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, May 19, 2012 - Departed: Zillah, WA - Destination: Zillah, WA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: none; private, commercial; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review October 27, 2010; seat: right; flight hours: 3,975 total, 717 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 140° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 57 °F, dew point 39 °F - Altimeter: 30.14 inHg - Observed at: KPSC ## 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 20120530009489A](https://openairdocs.org/incident/20120530009489A), May 30, 2012: Bell 206B, Burbank, WA, Substantial damage. Pilot was conducting aerial application fertilizer spraying over an apple orchard. The pilot was on the fourth pass at approximately 15 feet over the tree tops… ## Docket (7 files) The files NTSB released with the investigation on June 28, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83795. 8.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40371269&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Statements (item 2, .PDF, 126 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40371223&FileExtension=.PDF&FileName=Statements-Redacted.PDF - Photo 1- On-scene photo (item 3, .PDF, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40371224&FileExtension=.PDF&FileName=Photo%201-%20On-scene%20photo-Master.PDF - Photo 2- View of the engine and loose b-nut (item 4, .PDF, 84 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40371225&FileExtension=.PDF&FileName=Photo%202-%20View%20of%20the%20engine%20and%20loose%20b-nut-Master.PDF - Photo 3- Loose b-nut (item 5, .PDF, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40371226&FileExtension=.PDF&FileName=Photo%203-%20Loose%20b-nut-Master.PDF - Rolls Royce Report (item 6, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40371270&FileExtension=.PDF&FileName=Rolls%20Royce%20Report-Redacted.PDF - Maintenance Record (extract) (item 7, .PDF, 299 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40371227&FileExtension=.PDF&FileName=Maintenance%20Record%20(extract)-Redacted.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.