# NTSB CEN16LA154: Air Tractor AT 502, N301LA, Kilbourne, LA, April 18, 2016 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 3 · Limited · Final report - Date: April 18, 2016, 09:10 local (14:10 UTC) - Place: Kilbourne, LA - Coordinates: 32.999721, -91.315002 - Nearby events: https://openairdocs.org/map.md?lat=32.9997&lon=-91.3150&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report May 28, 2026 - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA Flight Standards District Office, Pratt & Whitney Canada Corp., Air Tractor, Inc - ADs cited in the narratives: [AD 2003-07-04](https://openairdocs.org/ad/2003-07-04) (OpenAirDocs) - NTSB case key (mKey): 93025 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN16LA154 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93025/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93025 - Page: https://openairdocs.org/ntsb/CEN16LA154 ## Probable cause The failure of the operator to comply with the terminating action of the airworthiness directive, which resulted in the subsequent failure and separation of the vertical stabilizer due to fatigue. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Empennage structure: vertical stab misc structure](https://openairdocs.org/ntsb-findings/01035534): Aircraft › Aircraft structures · Fatigue/wear/corrosion (probable cause); cases with it: [Air Tractor AT-502, 1 case](https://openairdocs.org/ntsb-findings/01035534/cases.md?model=0390303), [All aircraft, 1 case](https://openairdocs.org/ntsb-findings/01035534/cases.md) - [Empennage structure: vertical stab misc structure](https://openairdocs.org/ntsb-findings/01035534): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Air Tractor AT-502, 1 case](https://openairdocs.org/ntsb-findings/01035534/cases.md?model=0390303), [All aircraft, 1 case](https://openairdocs.org/ntsb-findings/01035534/cases.md) - [Empennage structure: vertical stab misc structure](https://openairdocs.org/ntsb-findings/01035534): Aircraft › Aircraft structures · Not serviced/maintained (probable cause); cases with it: [Air Tractor AT-502, 1 case](https://openairdocs.org/ntsb-findings/01035534/cases.md?model=0390303), [All aircraft, 1 case](https://openairdocs.org/ntsb-findings/01035534/cases.md) - [Maintenance](https://openairdocs.org/ntsb-findings/02062000): Personnel issues › Task performance · Other (probable cause); cases with it: [Air Tractor AT-502, 2 cases](https://openairdocs.org/ntsb-findings/02062000/cases.md?model=0390303), [All aircraft, 143 cases](https://openairdocs.org/ntsb-findings/02062000/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: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) (defining event); cases with it: [Air Tractor AT-502, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=0390303), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Air Tractor AT-502, 17 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0390303), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis **This report was modified on March 23, 2026. Please see the docket for this accident to view the original report.** The commercial pilot was conducting his second spray load application of the day to a field located about 1/4 mile north of the accident site. A farmer stated that the pilot's last passes were to finish spraying a tight area of the field that had trees at the end. A witness near the accident site saw the airplane turn at low altitude and then rapidly descend until ground impact. The airplane was destroyed by impact forces and a postimpact fire. Postaccident examination of the wreckage and ground scars revealed that the airplane impacted terrain in a steep, nose-down attitude. Examination of the engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The pilot had hypertension and left ventricular hypertrophy (LVH). However, it is unlikely that the pilot's underlying hypertension and LVH contributed to the accident. In December of 2025, the vertical stabilizer of the airplane was located in a wooded area northeast of the location where the main wreckage came to rest. Metallurgical examination of the vertical stabilizer revealed fractured surfaces on both fitting lobes with extensive post-fracture smearing damage. Thumbnail shaped areas contained macro features consistent with fatigue cracking which emanated from the forward face of the attach plate. A service letter and airworthiness directive required periodic examination of the vertical fin front spar fitting for cracks with the installation of the steel doubler as a “terminating action.” There was no evidence that the steel doubler had been installed. Maintenance records for the accident airplane were not made available, and investigators were unable to determine if the periodic examination for cracks was accomplished. It is most likely that the vertical stabilizer separated during the aerial application flight due to the progressive fatigue cracking within the front spar fitting. This separation resulted in a loss of airplane control and subsequent impact with terrain. ## Factual narrative The single-engine low-wing conventional-geared airplane was equipped with a Pratt and Whitney PT6A-34AG turbo-prop engine. According to the operator, the last annual inspection was performed on February 17, 2016. The airframe total time was 9,585 hours and the engine total time was 7,022 hours, with 445 hours since the last hot section inspection. On April 18, 2016, about 0910 central daylight time, an Air Tractor Inc AT-502 airplane, N301LA, impacted terrain during spray operations near Kilbourne, Louisiana. The pilot was fatally injured, and the airplane was destroyed. The airplane was registered to and operated by Pioneer Flying Service, Inc., under the provisions of Title 14 Code of Federal Regulations Part 137 as an aerial application flight. Day visual meteorological conditions prevailed for the flight, with no flight plan filed. The local flight departed a private airport about 0900. According to operator personnel, the pilot was conducting his second load of spray operations for the day to the same farm area, which was about ¼ mile north of the accident site. A witness near the accident noticed the airplane enter a rapid descent while in a turn until it impacted the ground. A post-crash fire ensued. The farmer whose field was being sprayed stated the pilot was "dressing up" a field, which had a tight area shaped like a bull nose, with trees at the end. The farmer did not witness the accident. He remarked the pilot was able to spray tight areas of fields that other pilots elected not to spray. During his last FAA medical examination, the pilot reported heterophoria (cross-eyes), previous treatment for a kidney stone, and long-standing hypertension. He also reported using nisoldipine, valsartan, and hydrochlorothiazide, commonly sold with the names Sular and Diovan-HCT. Used to treat his blood pressure, none of these medications are generally considered impairing. According to the autopsy report from the West Carroll Parish Coroner's Office in Oak Grove, Louisiana, the cause of death was multiple blunt force injuries and the manner of death was accident. The heart weighed 550 grams and was enlarged due to concentric left ventricular hypertrophy (LVH). The left wall of the ventricle was reported as 1.8 cm thick; measurements in other areas were not reported. Average for a man with the pilot's weight of 282 pounds is 443 grams with a range of 335-584 grams; average left ventricular wall thickness is about 1.3 cm. LVH is commonly caused by longstanding hypertension. Toxicology performed by the FAA's Bioaeronautical Sciences Research Laboratory identified valsartan in urine and cavity blood. Valsartan is described above. At 0915, the weather observation station at Morhouse Memorial Airport (BQP), Bastrop, Louisiana, located about 32 miles southwest of the accident site, reported the following conditions: wind 080 degrees at 4 knots, 10 miles visibility, clear skies, temperature 19°C, dew point 15°C, altimeter setting 30.24 inches of mercury.The pilot, age 48, held a commercial pilot certificate with an airplane single-engine land rating. The pilot held a second-class medical certificate issued on June 1, 2015, with the restriction that he must wear corrective lenses for near vision. The date of his last flight review was March 15, 2016. The airplane impacted a soft open field. Other than a set of electrical lines, no obstacles were in the immediate area of the wreckage. The wreckage had no signs of an in-flight impact with wires, trees, or other obstacles. The wooded area toward the sprayed field was searched for broken branches or other signs of tree impact, with none observed. The wreckage was confined to the immediate vicinity of the impact site. The impact crater contained pieces of engine cowling, windshield plexiglass, and the hopper top and lid. The engine penetrated about 3 ft deep into the soft soil. Radiating from the crater were impressions in the soil, consistent with impact marks from the leading edge of both wings. The wings were located about 10 feet away from these impressions. Both wings were crushed aft, with the left wing receiving more damage than the right wing. The aft fuselage and rudder showed signs of momentum toward the left side of the airplane. The ground impact markings and wreckage were consistent with a steep, nose down impact at low groundspeed. The fuselage was mostly destroyed by impact forces and a post-crash fire. All control surfaces were located and identified, except for the vertical stabilizer. The only piece of the vertical stabilizer that was located was a short piece of the stabilizer rear spar that remained attached to the lower portion of the rudder. The lower hinge point of the rudder was found fully intact with minimal damage. The end of the wire deflector cable that was attached to the top of the stabilizer was found underneath the cockpit wreckage. Multiple pieces of fire-damaged aluminum were identified as possible vertical stabilizer components, but none could be confirmed. A witness mark was observed on the top fuselage skin that corresponded to the shape of the vertical stabilizer's leading edge. The wings flaps were in the full up position. Flight control continuity was confirmed to the extent possible, with several components consumed by the fire or cut by emergency response personnel during the pilot's extrication. The aileron/rudder interconnect system, which is a system of cables that connect the rudder pedals to the aileron controls to assist the pilot with coordinated flight, had been removed from the airplane. The engine was damaged by the post-crash fire, with the inlet case fractured, causing complete separation of the accessories gearbox from the engine. Rotational signatures were observed throughout the compressor and power turbines and adjacent static components, consistent with the engine rotating under power during impact. There was no evidence of pre-impact anomalies of the engine, airframe, or propeller. Due tofire damage, data from a GPS unit found in the wreckage could not be downloaded. On December 8, 2025, the NTSB was notified that the vertical stabilizer was located in a wooded area about 990 ft northeast of where the main wreckage came to rest in the field. The component was secured and relocated to the NTSB Materials Laboratory in Washington, DC, for further examination. Both lobes of the stabilizer fin attach plate of the forward fitting were fractured. Microscopic examination of the fracture surfaces revealed post fracture smearing and macro features within tumbnails consistent with fatigue cracking. Secondary fatigue cracking on parallel planes was observed adjacent to the main plane of fatigue cracking on both facture surfaces. There was no doubler present and no evidence that one was previously installed in accordance with the terminating action of the AD 2003-07-04. Maintenance records were not made available during the investigation and were not available after the vertical stabilizer was located. Air Tractor issued Service Letter (SL) 155 **Revision 11/27/2002 regarding the Vertical Fin Front Spar Fitting. The SL directed an “inspection of the aluminum plate” for the vertical fin, every 100 hours, until a steel doubler plate was installed. If cracks were found, the plate must be replaced before installing the steel doubler. The SL required the action be incorporated before 2,000 hours total time. On May 22, 2003, the FAA issued AD 2003-07-04 that required repeated inspection of the vertical fin front spar fitting for cracks with the installation of the steel doubler as a “terminating action for the repetitive inspections.” ## Aircraft - Registration: [N301LA](https://openairdocs.org/deregistered/N301LA-2018-09-13), registration cancelled 2018-09-13, S/N 502-0037, built 1989 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT 502 - Registry model: [Air Tractor AT-502](https://openairdocs.org/model/air-tractor-at-502) (registry code 0390303) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-34AG](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-34ag) (registry code 52251, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 502-0037 - Year built: 1989 - Airframe hours: 9585 - Engines: Pratt and Whitney PT6A-34G 750 horsepower turbo prop - Damage: Destroyed - Fire: On-Ground - Flight: Aerial application, Part 137 - Operator: Pioneer Flying Service Inc - Registered owner: Pioneer Flying Service - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, February 17, 2016 - Departed: PRI, Pioneer, LA - Destination: PRI, Pioneer, LA - Equipment: Stall warning system, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 48; injuries: fatal; commercial; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review March 15, 2016; seat: front; toxicology performed; flight hours: 13,261 total, 2,463 in this make and model, 13,261 as pilot in command, 100 in the last 90 days, 50 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 80° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F, dew point 59 °F - Altimeter: 30.23 inHg - Observed at: KBQP, 32 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 20160418004939A](https://openairdocs.org/incident/20160418004939A), Apr 18, 2016: Air Tractor Inc AT-502, Terry, LA, Destroyed, 1 fatal. Aircraft was conducting aerial spraying operations. Aircraft departed with 300 gallons of product and ¾ fuel. It was the pilot?s second load of the morning.… ## Docket (14 files) The files NTSB released with the investigation on March 6, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93025. 38.1 MB in all. - Farmer statement (item 1, PDF, 1 page, 53 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5845968&FileExtension=pdf&FileName=Farmer%20statement-Rel.pdf - Witness statement (item 2, PDF, 1 page, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5833003&FileExtension=pdf&FileName=Witness%20statement_Redacted-Rel.pdf - Overhead view of accident site and sprayed field (item 3, PDF, 1 page, 462 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5833012&FileExtension=pdf&FileName=Overhead%20view%20of%20accident%20site%20and%20sprayed%20field-Rel.pdf - Photos of accident site and wreckage (item 4, PDF, 7 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5833276&FileExtension=pdf&FileName=Photos-Rel.pdf - Airframe examination report (item 5, PDF, 12 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5925299&FileExtension=pdf&FileName=Air%20Tractor%20report_Redacted-Rel.pdf - Toxicological report (item 6, PDF, 1 page, 108 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5834038&FileExtension=pdf&FileName=Toxicology%20report._Redacted-Rel.pdf - Wreckage release (item 7, PDF, 1 page, 5.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5834551&FileExtension=pdf&FileName=Wreckage%20Release%20-%20CEN16LA154_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation (item 8, PDF, 1 page, 126 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=5838155&FileExtension=pdf&FileName=Kyle%20Schroeder%20Party%20Form%20CEN16LA154_Redacted-Rel.pdf - CEN16LA154 - original NTSB report (item 9, PDF, 7 pages, 822 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20067075&FileExtension=pdf&FileName=Report_CEN16LA154_Original%20Report-Rel.pdf - 26-008 Materials laboratory factual report (item 10, PDF, 30 pages, 22.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20111587&FileExtension=pdf&FileName=26-008%20Materials%20Laboratory%20Factual%20Report%20(CEN16LA154)%20-%20FINAL-Rel.pdf - Airworthiness directive 2003 07 04 (item 11, PDF, 6 pages, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20068898&FileExtension=pdf&FileName=AD%202003%2007%2004-Rel.pdf - Maintenance records excerpt (item 12, PDF, 1 page, 665 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20067864&FileExtension=pdf&FileName=Maintenance%20Records%20Excerpt_Redacted-Rel.pdf - Air tractor service letter 155 revision 11/27/2002 (item 13, PDF, 5 pages, 65 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20069535&FileExtension=pdf&FileName=SL155-Rel.pdf - Memo to revise report and analysis (item 14, PDF, 23 pages, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20402964&FileExtension=pdf&FileName=Memo%20to%20revise%20analysis%20and%20PC%20-%20CEN16LA154_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.