# NTSB CEN17LA284: Air Tractor AT802, N816FF, Reyno, AR, July 18, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 18, 2017, 17:10 local (22:10 UTC) - Place: Reyno, AR - Coordinates: 36.35889, -90.816108 - Nearby events: https://openairdocs.org/map.md?lat=36.3589&lon=-90.8161&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Transporation Safety Board of Canada, Woodward, Federal Aviation Administration, Little Rock FSDO, Hartzell Propeller, Pratt & Whitney Canada, Air Tractor - NTSB case key (mKey): 95659 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN17LA284 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95659/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95659 - Page: https://openairdocs.org/ntsb/CEN17LA284 ## Probable cause The pilot’s inadvertent use of the propeller control, which caused the propeller to feather while in flight with the engine still operating, resulting in a loss of thrust and a subsequent forced landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Propeller system: propeller feather/reversing](https://openairdocs.org/ntsb-findings/01046123): Aircraft › Aircraft propeller/rotor · Incorrect use/operation (probable cause); cases with it: [All aircraft, 26 cases](https://openairdocs.org/ntsb-findings/01046123/cases.md) - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Pilot (probable cause); cases with it: [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/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: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot was returning to the landing strip after an uneventful spray flight when he noticed a rapid increase in engine torque shortly after he made a power reduction. The pilot stated that he “looked at my levers and pushed the prop lever all the way forward.” According to the pilot, there was insufficient thrust to maintain altitude and he made a forced landing in an open field. The airplane’s left wing impacted the ground during landing and the airplane skidded sideways to a stop. The right wingtip, right aileron, and right elevator were substantially damaged. Examination and bench testing revealed no evidence of a mechanical malfunction or failure that would have precluded normal engine operation. Engine control continuity was confirmed from the cockpit levers to their respective engine components, and the engine controls moved smoothly through their full range of motion. An analysis of the airplane’s engine monitor data revealed that the pilot had mistakenly moved the cockpit propeller lever instead of the power lever while he maneuvered to land. When the pilot moved the propeller control aft it increased propeller pitch which, in turn, decreased propeller speed (Np). As Np decreased there was a corresponding increase in engine torque. The data analysis revealed that Np decreased to the point where the constant speed unit (CSU) feather valve dumped oil pressure, and the propeller feathered. Engine torque then rapidly increased above the 5,100 ft-lbs limitation. Shortly after the propeller feathered, there was a rapid increase in fuel flow and engine torque, consistent with the pilot moving the power lever full forward with the propeller still feathered. The gas generator speed (Ng) and fuel flow remained relatively constant and the engine torque remained above 6,600 ft-lbs until the engine was shut down after the accident. ## Factual narrative On July 18, 2017, about 1710 central daylight time, an Air Tractor AT-802A airplane, N816FF, was substantially damaged in an accident near Reyno, Arkansas. The commercial pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 135 aerial-application flight. The pilot reported that, after an uneventful spray flight, he was maneuvering to land on private airstrip when he noticed an increase in engine torque shortly after he made a power reduction. The pilot recalled that the engine torque increased to about 6,000 ft-lbs and the propeller speed decreased to about 710 rpm. The pilot stated that he “looked at my levers and pushed the prop lever all the way forward.” The pilot stated that there was insufficient thrust to maintain altitude and that he made a forced landing in an open soybean field. The airplane’s left wing impacted the ground during landing and the airplane skidded sideways to a stop. The right wingtip, right aileron, and right elevator were substantially damaged. Examination of the airplane at the accident site confirmed flight control continuity. The power lever was at idle, the propeller lever was in feather, and the start control (condition lever) was in cut-off. Engine control continuity was confirmed from the cockpit levers to their respective engine components, and the engine controls moved smoothly through their full range of motion. The bleed air reference line between the fuel control unit (FCU) and the constant speed unit (CSU) was properly installed and secured. A fuel sample from the header tank did not exhibit any contamination and was consistent with Jet-A aviation fuel. Both wing tanks contained fuel, and the engine monitor indicated that there were 55.5 gallons and 142 gallons remaining in the left and right fuel tanks, respectively. The airframe fuel lines were intact and did not exhibit any leaks. The FCU filter housing was removed, and it contained fuel. The propeller remained attached to the engine and appeared to be undamaged. The propeller beta system was found properly rigged; the beta plunger valve was flush with the cap nut, and the beta block was properly seated under the guide pin in the propeller beta ring. The engine was removed from the airplane and sent to the manufacturer for additional examination. A teardown inspection of the engine did not reveal any evidence of mechanical malfunction or failure that would have precluded normal engine operation. The clearance between the propeller shaft and the propeller sleeve met the manufacturer’s design limits and the dimensions between the propeller shaft and the internal oil transfer tube/oil jet were within specifications. Bench testing of the engine-driven fuel pump, flow divider, FCU, compressor bleed valve, CSU (propeller governor), and overspeed governor did not reveal any anomalies that would have precluded normal engine operation. An analysis of the airplane’s engine monitor data (see figure 1) revealed that towardthe end of the flight, between 1708:44 to 1709:19, the propeller speed (Np) decreased at three separate rates, consistent with the cockpit propeller lever being moved aft at three different rates. The aft movement of the propeller control increased propeller pitch which, in turn, decreased Np. The data analysis also indicated that as Np decreased, there was a corresponding increase in engine torque. Between 1708:45 and 1708:58, the Np decreased from 92% to 84% and there was a 10% decrease in thrust. Between 1708:58 and 1709:14, the Np continued to decrease from 84% to 65% and there was another 10% decrease in thrust. At 1709:14, the Np had decreased to 62% (1,060 rpm) at which point the CSU feather valve dumped oil pressure from the propeller causing it to feather. Postaccident bench testing of the CSU confirmed that the feather valve would dump oil pressure at 1,060 rpm. When the propeller went into feather, the engine torque rapidly increased above the 5,100 ft-lbs limitation. At 1709:25, there was a rapid increase in fuel flow and engine torque, consistent with the pilot moving the power lever full forward with the propeller still feathered. At 1709:28, the engine torque reached 6,920 ft-lbs. The gas generator speed (Ng) and fuel flow remained relatively constant and the engine torque remained above 6,600 ft-lbs until the engine was shut down after the accident. Figure 1 – Engine Monitor Data ## Aircraft - Registration: N816FF (not matched to a registry record) - Reported make and model: AIR TRACTOR AT802 (A) - Category: Airplane - Serial number: 802A-0714 - Year built: 2017 - Airframe hours: 8.5 - Engines: Pratt & Whitney Canada PT6A-65AG 1295 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: C & C Flying Service Inc. - Registered owner: C & C Flying Service Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, June 28, 2017, 8.5 hours before - Departed: PVT, Reyno, AR - Equipment: Data recorder ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review November 25, 2016; seat: center; restraint: 5-point; flight hours: 11,413 total, 4,317 in this make and model, 11,378 as pilot in command, 325 in the last 90 days, 100 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 91 °F, dew point 73 °F - Altimeter: 30.05 inHg - Observed at: 4M9, 10 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 20170718009119A](https://openairdocs.org/incident/20170718009119A), Jul 18, 2017: Air Tractor AT-802, Reyno, AR, Substantial damage. On July 18, 2017 at approximately 1730 CDT, N816FF a Air Tractor 802A aircraft, registered to Air Tractor, inc. operated by a commercial pilot landed in a… ## Docket (11 files) The files NTSB released with the investigation on June 9, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95659. 15.1 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12045217&FileExtension=pdf&FileName=01%20-%20Pilot%20Report_Redacted-Rel.pdf - FAA inspector statement (bill kelly) (item 2, PDF, 2 pages, 14 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12045965&FileExtension=pdf&FileName=02%20-%20FAA%20Inspector%20Statement%20(Bill%20Kelly)-Rel.pdf - On-scene examination report (air tractor) (item 3, PDF, 21 pages, 5.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12044749&FileExtension=pdf&FileName=03%20-%20On-Scene%20Report%20(Air%20Tractor)_Redacted-Rel.pdf - Engine removal report (air tractor) (item 4, PDF, 7 pages, 495 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12046001&FileExtension=pdf&FileName=04%20-%20Engine%20Removal%20Report%20(Air%20Tractor)_Redacted-Rel.pdf - Power quadrant comparison (air tractor) (item 5, PDF, 3 pages, 250 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12045227&FileExtension=pdf&FileName=05%20-%20Power%20Quadrant%20Comparison%20(Air%20Tractor)_Redacted-Rel.pdf - Engine examination report (pratt and whitney) (item 6, PDF, 44 pages, 4.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12045975&FileExtension=pdf&FileName=06%20-%20Pratt%20and%20Whitney%20Examination%20Report_Redacted-Rel.pdf - Engine monitor data (accident flight) (item 7, CSV, 324 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12045237&FileExtension=csv&FileName=09%20-%20Engine%20Monitor%20Data%20(Accident%20Flight)-Rel.csv - Engine monitor data plots (item 8, PDF, 2 pages, 243 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12046288&FileExtension=pdf&FileName=10%20-%20Engine%20Monitor%20Data%20Plots-Rel.pdf - Weather (item 9, PDF, 1 page, 20 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12046395&FileExtension=pdf&FileName=11%20-%20Weather%20Data-Rel.pdf - Statement of party representatives to NTSB investigation (item 10, PDF, 3 pages, 669 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12046195&FileExtension=pdf&FileName=12%20-%20NTSB%20Party%20Forms_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 11, PDF, 1 page, 321 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12045811&FileExtension=pdf&FileName=13%20-%20Wreckage%20Release%20(Signed)_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.