# NTSB CEN15LA389: Air Tractor AT 502B, N61267, Monroe, NE, August 27, 2015 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: August 27, 2015, 12:00 local (17:00 UTC) - Place: Monroe, NE - Coordinates: 41.51361, -97.646942 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.5136&lon=-97.6469&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report November 15, 2018 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Air Tractor Inc, AAII of the Czech Republic, FAA Lincoln FSDO, GE Engines - NTSB case key (mKey): 91892 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN15LA389 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91892/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91892 - Page: https://openairdocs.org/ntsb/CEN15LA389 ## Probable cause Loss of propeller thrust for reasons that could not be determined, since examination of the airplane's engine, propeller, and associated accessories revealed no anomalies. ## 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: [Air Tractor AT-502B, 7 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=0390307), [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-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Air Tractor AT-502B, 7 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=0390307), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Maneuvering-low-alt flying: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Air Tractor AT-502B, 14 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=0390307), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Air Tractor AT-502B, 46 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390307), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Landing: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Air Tractor AT-502B, 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=0390307), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The commercial pilot was performing an aerial application flight when the airplane experienced a partial loss of engine power. The engine instruments showed that the engine was operating, but was producing less than idle power. The pilot applied full throttle with no effect. He subsequently turned the airplane into the wind, lowered the flaps, and when he heard corn hitting the bottom of the airplane, pulled the control stick full aft to stall the airplane. The left wing dropped and the airplane turned 90° as it impacted the ground. The engine continued to run until the pilot shut it down and exited the airplane. An examination of the airplane's engine, propeller governor, fuel control unit, and fuel pump revealed no anomalies. An engine data recorder showed an exceedance of the N1 upper limit, followed by a decrease in internal turbine temperature, N1, and propeller rpm, consistent with a lower output by the engine. The data were reviewed by the engine manufacturer, who concluded that the data were consistent with a feathered propeller; however, the reason for the propeller feathering could not be determined based on the available information. ## Factual narrative On August 27, 2015, about 1200 central daylight time, an Air Tractor, AT-502B, single-engine turboprop airplane, N61267, had a partial loss of engine power during low-altitude maneuvering flight and impacted terrain near Monroe, Nebraska. The pilot sustained minor injuries and the airplane sustained substantial damage to both wings, the horizontal stabilizer, and elevator. The airplane was registered to, and was operated by Red Willow Aviation Spraying, Inc.; McCook, Nebraska, as a 14 Code of Federal Regulations Part 137 aerial application flight. Day visual meteorological conditions prevailed, and a flight plan had not been filed for the local flight which had departed about 1130 from Genoa Municipal Airport (97Y), Genoa, Nebraska.The pilot was seeding a cover crop into corn when he experienced a partial loss of engine power. The engine instruments showed the engine was operating, but was producing less than idle power. The pilot pushed the throttle to full power, with no effect. At that point, he knew he had to land. The pilot turned the airplane into the wind and lowered the flaps. As he heard corn start hitting the bottom of the airplane, the pilot pulled the control stick full aft to stall the airplane. The left wing dropped, the airplane turned 90 degrees, and impacted the ground sideways. The right wing subsequently struck the ground and the airplane came to rest upright. The engine continued to run until the pilot shut it down and exited the airplane. An examination of the wreckage showed there was adequate fuel on-board, there was no fuel spill, and no postimpact fire. The airplane's engine and propeller governor were examined and no anomalies were found. The fuel control unit and fuel pump were removed and sent to the manufacturer in Prague, Czech Republic, for examination. A Turbine Start Limit and Monitor (TSLM) and a USB thumb drive, which contained Global Positioning Satellite (GPS) data from a GPS unit on board the airplane, were sent to the NTSB Vehicle Recorder's Laboratory for examination. The examination of the fuel control unit and fuel pump revealed no anomalies. The GPS data on the USB thumb drive was examined and did not include the accident flight. The TSLM, which monitors internal turbine temperature, N1, N2, torque, oil pressure, and bus voltage, and records at engine startup and when the parameters are exceeded, recorded 74 events. Event 74 was triggered by the N1 parameter being set above the user set upper limit. The exceedance ended 1.5 seconds into the event. Following the exceedance, the internal turbine temperature, N1, and N2 (propeller rpm) decreased over time, consistent with a lower output by the engine. The TSLM data was reviewed by the engine manufacturer who concluded that the propeller went into feather either by an incorrect pilot command or a governor problem. The manufacturer also noted the engine was being operated above the manual temperature limits at the time of the event and the internal turbinetemperature and core speed did not correlate correctly. The manufacturer could only attribute that to scaling of the data or improper engine operation. ## Aircraft - Registration: [N61267](https://openairdocs.org/deregistered/N61267-2018-10-22), registration cancelled 2018-10-22, S/N 502B-0303, built 1995 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT 502B - Registry model: [Air Tractor AT-502B](https://openairdocs.org/model/air-tractor-at-502b) (registry code 0390307) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52034, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 502B-0303 - Year built: 1995 - Engines: WALTER M601E11 turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Red Willow Aviation Spraying Inc, doing business as Red Willow Aviation Spraying Inc - Registered owner: Red Willow Aviation Spraying Inc - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, November 17, 2014, 311 hours before - Departed: 97Y, GENOA, NE - Destination: 97Y, GENOA, NE - Equipment: Handheld GPS, Data recorder, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 38; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; seat: single; restraint: 4-point; flight hours: 1,400 total, 970 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 120° at 9 knots, gusting 14 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 64 °F - Altimeter: 29.97 inHg - Observed at: KOLU, 14 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 20150827016119A](https://openairdocs.org/incident/20150827016119A), Aug 27, 2015: Air Tractor Inc AT-502B, Genoa, NE, Substantial damage. Pilot completed a run in adjacent field and was preparing for another pass. Aircraft lost power and pilot was unable to restore. Unable to make a nearby road,… ## Other investigations on N61267 (1) 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. - [NTSB NYC08CA279](https://openairdocs.org/ntsb/NYC08CA279), Aug 13, 2008: Air Tractor AT-502B (N61267), Tunica, MS, substantial damage. Probable cause: The pilot's failure to maintain clearance from the power lines during low-altitude maneuvers. ## Docket (11 files) The files NTSB released with the investigation on August 30, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91892. 4.3 MB in all. - Turbine Engine Monitor and Limiter Factual Report (item 1, .PDF, 313 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466227&FileExtension=.PDF&FileName=Turbine%20Engine%20Monitor%20and%20Limiter%20Factual%20Report-Master.PDF - Turbine Engine Monitor and Limiter Factual Report - Attachment 1 (item 2, .CSV, 15 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466228&FileExtension=.csv&FileName=Turbine%20Engine%20Monitor%20and%20Limiter%20Factual%20Report%20-%20Attachment%201-Master.csv - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 3, .PDF, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466229&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Pilot's Statement (item 4, .PDF, 14 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466230&FileExtension=.PDF&FileName=Pilot%27s%20Statement-Master.PDF - Investigator's Memorandum of Engine Componenet Examinations Summary (item 5, .PDF, 221 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466231&FileExtension=.PDF&FileName=Investigator%27s%20Memorandum%20of%20Engine%20Componenet%20Examinations%20Summary-Master.PDF - Weather Summary, Columbus, Nebraska (item 6, .PDF, 14 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466232&FileExtension=.PDF&FileName=Weather%20Summary,%20Columbus,%20Nebraska-Master.PDF - Fuel Quality Tests Summary (item 7, .PDF, 12 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466233&FileExtension=.PDF&FileName=Fuel%20Quality%20Tests%20Summary-Master.PDF - Statement of Party Representatives to NTSB Investigation, Air Tractor (item 8, .PDF, 96 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466234&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation,%20Air%20Tractor-Master.PDF - Statement of Party Representatives to NTSB Investigation, GE Engines (item 9, .PDF, 81 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466235&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation,%20GE%20Engines-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 10, .PDF, 246 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466236&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Master.PDF - Air Tractor Airframe Report (item 11, .PDF, 6 photos, 767 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40466237&FileExtension=.PDF&FileName=Air%20Tractor%20Airframe%20Report-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.