# NTSB ERA20LA071: Hughes OH 6A, N6186U, Preston, GA, January 8, 2020 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: January 8, 2020, 13:39 local (18:39 UTC) - Place: Preston, GA - Coordinates: 31.962499, -84.527496 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=31.9625&lon=-84.5275&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: MD Helicopters, FAA/FSDO, USDA, Rolls-Royce, Thoroughbred Aviation Maintenance - NTSB case key (mKey): 100789 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA20LA071 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100789/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100789 - Page: https://openairdocs.org/ntsb/ERA20LA071 ## Probable cause A partial loss of engine power for reasons that could not be determined based on the available information. ## 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: [Hughes OH-6A, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=4470905), [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. - [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Hughes OH-6A, 2 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=4470905), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Autorotation: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Hughes OH-6A, 2 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=4470905), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-flare/touchdown: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Hughes OH-6A, 1 case](https://openairdocs.org/ntsb-events/096/sequence.md?model=4470905), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis During the flight to observe feral swine invading farm fields, the pilot noted a loss of engine power and rotor rpm. He maneuvered the helicopter away from trees for an autorotation to an open, plowed cornfield. During the landing on rough terrain, the helicopter nosed forward and the main rotor blades contacted the ground, resulting in substantial damage to the helicopter. A postaccident examination of the flight controls, drive train, fuel system, main rotor system, and tail rotor system did not reveal evidence of a preexisting mechanical malfunction or anomaly. The engine was removed and placed on a test stand; it ran normally for about 2 minutes before the run was concluded. A laboratory test of a fuel sample was unremarkable. The reason for the loss of engine power could not be determined. ## Factual narrative On January 8, 2020, about 1339 eastern standard time, a Hughes OH-6A, N6186U, was substantially damaged when it was involved in an accident near Preston, Georgia. The commercial pilot and one crewmember sustained minor injuries. The helicopter was registered to the U.S. Department of Agriculture and was operated as a public aerial observation flight. The pilot reported that the purpose of the flight was to conduct aerial wildlife damage management operations. A feral swine was located and the pilot informed the ground crew via radio of its location. Shortly thereafter, the pilot noted a loss of engine power and rotor rpm. The pilot maneuvered the helicopter away from trees for an autorotation to an open, plowed cornfield. During the landing on rough terrain, the helicopter nosed forward and the main rotor blades contacted the ground. The engine appeared to be running at the time of impact. A Federal Aviation Administration inspector responded to the accident site and examined the wreckage. The tail boom was separated from the helicopter and three of the four main rotor blades were separated from the hub. The fuselage sustained structural damage. The operator reported that the N2 (power turbine) governor was changed before the flight due to a problem on a previous flight. The wreckage was retained for further examination, and examination of the flight control system, drive train, main rotor system, and tail rotor system did not reveal evidence of a preexisting mechanical malfunction or anomaly. The engine was removed from the airframe and sent to a factory-authorized overhaul facility for further examination. Continuity was established for the N1 (gas producer turbine) and N2 rotors. The rotors moved freely without binding or noise. Control continuity was confirmed from the collective twist grip to the fuel control unit. The control linkage to the power turbine governor was fractured at the engine firewall due to impact forces. The engine was installed on a test stand and prepared for a test run. The engine performed satisfactorily at takeoff power for 2 minutes as well as two lower power test points over a test period totaling about 20 minutes. Following the test run, the power turbine governor, fuel control unit, fuel nozzle, and fuel pump were bench-tested. The power turbine governor that was removed and replaced before the accident flight was also tested. All units tested satisfactorily and within the manufacturers' specifications. Examination of the fuel system revealed no anomalies, and the fuel lines and filters were free of contamination and obstructions. A fuel sample was tested in a laboratory with normal results. ## Aircraft - Registration: [N6186U](https://openairdocs.org/deregistered/N6186U-2020-04-09), registration cancelled 2020-04-09, S/N 69-16048 (OpenAirDocs) - Reported make and model: Hughes OH 6A (No Series) - Registry model: [Hughes OH-6A](https://openairdocs.org/model/hughes-oh-6a) (registry code 4470905) (OpenAirDocs) - Category: Helicopter - Serial number: 69-16048 - Year built: 1969 - Airframe hours: 12987 - Engines: Allison 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Aerial observation, Public use - Operator: US Dept Of Agriculture - Registered owner: US Dept Of Agriculture - Airworthiness certificate: None - Last inspection: 100 hour, October 10, 2019, 14 hours before - Departed: Preston, GA - Destination: ABY, Albany, GA - Equipment: Onboard weather, Handheld GPS, Electronic flight bag or handheld device, ADS-B, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 62; injuries: minor; private, commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review July 31, 2019; seat: right; restraint: 4-point; flight hours: 10,175 total, 8,229 in this make and model, 10,047 as pilot in command, 93 in the last 90 days, 36 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 21 °F - Altimeter: 30.43 inHg - Observed at: KCSG, 39 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 20200108007629A](https://openairdocs.org/incident/20200108007629A), Jan 8, 2020: Hughes OH-6A, Preston, GA, Substantial damage. On January 8, 2020, a Hughes OH-6A, N6186U, was substantially damaged following a loss of engine power and subsequent autorotation near Preston, Georgia. The… ## Docket (6 files) The files NTSB released with the investigation on March 4, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100789. 27.3 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 5.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9776713&FileExtension=pdf&FileName=6120%20p%201_Redacted-Rel.pdf - Written statement - mechanic (item 2, PDF, 2 pages, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9540140&FileExtension=pdf&FileName=4%20Greg%20Parsons%20Statement%20(Mechanic)_Redacted-Rel.pdf - FAA inspector statement - engine examination (item 3, PDF, 2 pages, 266 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9540149&FileExtension=pdf&FileName=5%20FAA%20Inspector%20Statement%20Engine%20Exam-Rel.pdf - Rolls royce engine investigation report (item 4, PDF, 14 pages, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9540773&FileExtension=pdf&FileName=8%20Rolls%20Royce%20Engine%20Investigation%20Report-Rel.pdf - Fuel test results (item 5, PDF, 2 pages, 122 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9541426&FileExtension=pdf&FileName=9%20Fuel%20Test%20Results_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation (item 6, PDF, 18 pages, 17.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9541333&FileExtension=pdf&FileName=10%20Party%20Forms_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.