# NTSB ERA24LA375: Air Tractor AT-802, N802JF, Hickory Valley, TN, September 10, 2024 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: September 10, 2024, 08:43 local (13:43 UTC) - Place: Hickory Valley, TN - Coordinates: 35.183506, -89.100322 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.1835&lon=-89.1003&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: No injuries - Injuries: 1 uninjured - Status: Completed, report October 22, 2025 - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO, Transportation Safety Board of Canada, Pratt & Whitney Canada - NTSB case key (mKey): 195093 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA24LA375 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/195093/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=195093 - Page: https://openairdocs.org/ntsb/ERA24LA375 ## Probable cause A partial loss of engine power due to a leak in the fuel control unit bellows, which resulted in the fuel valve moving to minimum fuel flow. ## 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 · Fatigue/wear/corrosion (probable cause); cases with it: [Air Tractor AT-802, 1 case](https://openairdocs.org/ntsb-findings/01057320/cases.md?model=0390305), [All aircraft, 59 cases](https://openairdocs.org/ntsb-findings/01057320/cases.md) - [Engine fuel and control: fuel controlling system](https://openairdocs.org/ntsb-findings/01057320): Aircraft › Aircraft power plant · Inadequate inspection (probable cause); cases with it: [Air Tractor AT-802, 1 case](https://openairdocs.org/ntsb-findings/01057320/cases.md?model=0390305), [All aircraft, 59 cases](https://openairdocs.org/ntsb-findings/01057320/cases.md) - [Engine fuel and control: fuel controlling system](https://openairdocs.org/ntsb-findings/01057320): Aircraft › Aircraft power plant · Not serviced/maintained; cases with it: [Air Tractor AT-802, 1 case](https://openairdocs.org/ntsb-findings/01057320/cases.md?model=0390305), [All aircraft, 59 cases](https://openairdocs.org/ntsb-findings/01057320/cases.md) - [Environmental issues](https://openairdocs.org/ntsb-findings/03010000): Environmental issues › Operating environment · Effect on equipment (probable cause); cases with it: [Air Tractor AT-802, 1 case](https://openairdocs.org/ntsb-findings/03010000/cases.md?model=0390305), [All aircraft, 14 cases](https://openairdocs.org/ntsb-findings/03010000/cases.md) - [Maintenance: repair](https://openairdocs.org/ntsb-findings/02062015): Personnel issues › Task performance · Maintenance personnel; cases with it: [Air Tractor AT-802, 1 case](https://openairdocs.org/ntsb-findings/02062015/cases.md?model=0390305), [All aircraft, 99 cases](https://openairdocs.org/ntsb-findings/02062015/cases.md) - [Action: lack of action](https://openairdocs.org/ntsb-findings/02041030): Personnel issues › Action/decision · Maintenance personnel; cases with it: [Air Tractor AT-802, 2 cases](https://openairdocs.org/ntsb-findings/02041030/cases.md?model=0390305), [All aircraft, 792 cases](https://openairdocs.org/ntsb-findings/02041030/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-802, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=0390305), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Air Tractor AT-802, 4 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390305), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot of the aerial application airplane reported that he departed his base airport to spray fields about 6 miles away. He had made multiple passes over the target fields when he noticed the turboprop engine’s fuel flow was lower than he had set. He pushed the power lever forward and the engine began to lose power. The pilot then pushed the power and condition levers to the forward stops in an attempt to regain power, but the engine continued to “roll back.” He jettisoned the aerial application payload in the hopper and initiated a forced landing. The airplane impacted a hay field and bounced on a slight uphill section before coming to rest. The airplane’s fuselage and engine mounts were substantially damaged during the off-airport landing. Review of data downloaded from the engine monitoring system showed that about 10 minutes after takeoff, the fuel flow began to decrease from about 82 gallons per hour to about 11 gallons per hour over 24 seconds. Examination of the engine’s fuel control unit (FCU) found the bellows exhibited corrosion and was leaking between the bellows and end cap. A review of maintenance records showed that a service bulletin (SB) was issued by the FCU manufacturer that called for the replacement of the bellows due to its age; however, the SB was not required by FAA airworthiness directive and was not complied with at overhaul or during any subsequent repair. The engine manufacturer reported that a leak in the bellows would have allowed the bellows to expand, subsequently moving the FCU fuel valve to the minimum fuel flow output as observed in the engine data recorded and as described by the pilot, preventing further power modulation. Had the actions prescribed by the SB been complied with, it is likely that the bellows would have been replaced before they began leaking and the loss of engine power occurred. The operator reported that the airplane was mainly used for spraying and fertilizing. It is possible that the corrosive chemicals used during those operations contributed to the corrosion of the bellows. ## Factual narrative On September 10, 2024, about 0843 central daylight time, an Air Tractor AT-802, N802JF, was substantially damaged when it was involved in an accident near Hickory Valley, Tennessee. The airline transport pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The pilot reported that he departed his base airport to spray fields about 6 miles to the southwest. He had made multiple passes over the target fields when he noticed the fuel flow was lower than he had set. He pushed the power lever forward to increase power and the engine began to lose power. The pilot then pushed the power and condition levers to the forward stops in an attempt to regain power, but the engine continued to “roll back.” He jettisoned the aerial application payload in the hopper and initiated a forced landing. The airplane impacted a hay field and bounced on a slight uphill section before coming to rest. Postaccident examination of the airplane found substantial damage to the engine mounts and fuselage. The examination also confirmed continuity of controls from the flight controls in the cockpit to the respective flight control surfaces. Continuity of the throttle control was also established from the control in the cockpit to the actuator on the fuel control unit, which moved from stop to stop. The pilot reported that he departed with 176 gallons of Jet-A aviation fuel. Review of data downloaded from the engine monitoring system showed that about 26 minutes after the recording began and about 10 minutes after takeoff, the fuel flow began to drop. It dropped from about 82 gallons per hour to about 11 gallons per hour over 24 seconds. The torque, propeller rpm, and gas generator speed all began to drop coincident with the decreased fuel flow until the end of the data. The fuel control unit (FCU) and engine-driven fuel pump were removed, tested, and examined. The engine-driven fuel pump tested within parameters and was not examined further. Testing of the FCU indicated that fuel flow in the P3 schedule and the start and acceleration schedule was lower than the component maintenance manual minimum limit for P3 pressures below 100 psia. The FCU was partially disassembled and the bellows, when removed, showed signs of external surface contamination and corrosion. A leakage check was performed on the bellows that showed an increase in length, indicative of a potential leak. The bellows were then internally pressurized and submerged in a fluid; the bellows showed leakage at the solder joint between the bellows and end cap. Materials analysis found a silver deficiency at the interface of the solder joint, which is consistent with oxidation due to corrosion of the bellows. The engine manufacturer reported that a leak in the bellows would have allowed the bellows to expand, subsequently moving the FCU fuel valve to the minimum fuel flow output and preventing further power modulation, consistent with what wasobserved in the engine data recorded at the time of the event. Woodward Service Bulletin (SB) 83212-73-023, Engine Fuel and Control – Main Engine Control (MEC) – CDP Bellows Assembly Inspection, was issued October 13, 2014. It includes instructions to measure the bellows length (“L” dimension marked on the part) for various models. Based on the part number of the bellows from the accident airplane, which was not marked with an “L” length reference, the SB states that the bellows were manufactured before January 1993 and that it shall be replaced. It also states this should be accomplished anytime the unit is returned for service. Manufacturer records for the FCU showed it was originally shipped on May 11, 1988, and the most recent shipment from the manufacturer was on April 27, 1993, with no returns recorded since then. A review of maintenance records and reports from the FCU repair shop showed that the FCU was overhauled in 2019 and repaired in 2021 and 2023. The repair facility was a licensed repair service facility (LRSF) for the manufacturer of the FCU. They reported that the service bulletin was not complied with during the overhaul or during any of the repairs. The FCU manufacturer reported that they expect the LRSF to perform its services in strict accordance with the component maintenance manual, SBs, Federal regulations, special program announcements, and any agreements between the manufacturer and the LRSF. The manufacturer also confirmed that a copy of the SB had been sent to the facility that repaired the FCU. The operator was asked about the types of operation the airplane is used for and stated that the airplane was mainly used for spraying and fertilizing. FAA advisory circular 43-4B states “practically all chemicals used in dusting and spraying operations are corrosive by nature and hasten deterioration of fabric, metal, and wood. It is essential to safe operation that precautions be taken to prevent corrosion and deterioration of wood, metal, and fabric.” ## Aircraft - Registration: [N802JF](https://openairdocs.org/aircraft/N802JF), registered now, S/N 802-0623, built 2015 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT-802 - Registry model: [Air Tractor AT-802](https://openairdocs.org/model/air-tractor-at-802) (registry code 0390305) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-65AG](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-65ag) (registry code 52109, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 802-0623 - Year built: 2015 - Airframe hours: 5325.1 - Engines: P&W CANADA PT6A-65AG 1295 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Miles Flying Service Inc - Registered owner: Miles Flying Service Inc - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, July 2, 2024, 68 hours before - Departed: M08, Bolivar, TN - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review March 19, 2024; seat: front; restraint: 5-point; flight hours: 10,351 total, 3,068 in this make and model ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 63 °F - Altimeter: 30.11 inHg - Observed at: M08, 3 nm away - METAR: KM08 101455Z AUTO VRB03KT 10SM CLR 24/17 A3011 RMK A01 ## 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 20240910013889A](https://openairdocs.org/incident/20240910013889A), Sep 10, 2024: Air Tractor Inc AT-802, Hickory Valley, TN, Substantial damage. On September 10, 2024, about 0843 central daylight time, an Air tractor AT-802, was substantially damaged when it was involved in an accident near Hickory… ## Docket (16 files) The files NTSB released with the investigation on October 22, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=195093. 18.1 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995520&FileExtension=pdf&FileName=6120.1%20Final%20ERA24LA375_Redacted-Rel.pdf - Memorandum for record a�� types of aircraft operation (item 2, PDF, 1 page, 62 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995095&FileExtension=pdf&FileName=MOR%20Type%20of%20Operations-Rel.pdf - Maintenance record excerpts (item 3, PDF, 6 pages, 9.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995105&FileExtension=pdf&FileName=Maintenance%20log%20excerpts_Redacted-Rel.pdf - Woodward service bulletin sb 83212-73-023 (item 4, PDF, 12 pages, 639 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995280&FileExtension=pdf&FileName=Woodward%20SB%2083212-73-023-Rel.pdf - Change of registration (n) number (item 5, PDF, 2 pages, 515 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995564&FileExtension=pdf&FileName=Change%20of%20Registration%20(N)%20Number_Redacted-Rel.pdf - Air tractor AT-802 fuel system schematic (item 6, PDF, 2 pages, 206 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995807&FileExtension=pdf&FileName=AT-802%20Fuel%20Schematic-Rel.pdf - Memorandum for record a�� fuel control unit repair shop (item 7, PDF, 5 pages, 75 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19007601&FileExtension=pdf&FileName=MOR%20VSE%20Aviation-Rel.pdf - Memorandum for record a�� fuel control unit manufacturer q&a (item 8, PDF, 2 pages, 117 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995467&FileExtension=pdf&FileName=MOR%20Woodward%20Q%26A-Rel.pdf - Memorandum for record a�� FAA on-scene examination (item 9, PDF, 2 pages, 66 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19001458&FileExtension=pdf&FileName=MOR%20FAA%20On%20Scene-Rel.pdf - Engine examination summary (item 10, PDF, 12 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995620&FileExtension=pdf&FileName=ERA24LA375%20Engine%20Examination%20Summary-Rel.pdf - Memorandum for record a�� engine manufacturer report excerpts (item 11, PDF, 8 pages, 264 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19001877&FileExtension=pdf&FileName=MOR%20P%26WC%20Report-Rel.pdf - Memorandum for record a�� fuel control unit manufacturer report excerpts (item 12, PDF, 7 pages, 594 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995115&FileExtension=pdf&FileName=MOR%20Woodward%20Report-Rel.pdf - Avionics flight data (item 13, XLSX, 791 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995125&FileExtension=xlsx&FileName=N802JF%20Recovered%20Data-Rel.xlsx - Engine data figure (item 14, PNG, 806 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995135&FileExtension=png&FileName=Flight%20data%20figure-Rel.png - Evidence control form (item 15, PDF, 1 page, 325 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18995664&FileExtension=pdf&FileName=FCU%20Evidence%20Control%20Form_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 16, PDF, 1 page, 131 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19025627&FileExtension=pdf&FileName=ERA24LA375%20Release-of-Wreckage-Form%20Signed_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.