# NTSB CEN21LA286: Ayres S2R-T34, N4328P, Leoti, KS, June 21, 2021 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: June 21, 2021, 16:15 local (21:15 UTC) - Place: Leoti, KS - Coordinates: 38.471722, -101.35047 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.4717&lon=-101.3505&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Hazardous material leak/spill](https://openairdocs.org/ntsb-events/450) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA - NTSB case key (mKey): 103313 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA286 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103313/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103313 - Page: https://openairdocs.org/ntsb/CEN21LA286 ## Probable cause The pilot’s loss of visibility in the cockpit due to foam created by the chemicals loaded in the hopper, which resulted in his inability to maintain airplane control during low-level flight and an impact with terrain. Contributing to the accident was the combining of chemicals known to produce foam and the pilot’s failure to perform a jar test before flight as recommended. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Ayres S2R-T34, 5 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=0970106), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Fluids](https://openairdocs.org/ntsb-findings/01071000): Aircraft › Fluids/misc hardware · Fluid condition (probable cause); cases with it: [Ayres S2R-T34, 1 case](https://openairdocs.org/ntsb-findings/01071000/cases.md?model=0970106), [All aircraft, 11 cases](https://openairdocs.org/ntsb-findings/01071000/cases.md) - [Sensory ability/limitation: visual function](https://openairdocs.org/ntsb-findings/02011510): Personnel issues › Physical · Pilot (probable cause); cases with it: [Ayres S2R-T34, 1 case](https://openairdocs.org/ntsb-findings/02011510/cases.md?model=0970106), [All aircraft, 32 cases](https://openairdocs.org/ntsb-findings/02011510/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Ayres S2R-T34, 4 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=0970106), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/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: Hazardous material leak/spill](https://openairdocs.org/ntsb-events/450) (defining event); cases with it: [Ayres S2R-T34, 1 case](https://openairdocs.org/ntsb-events/450/sequence.md?model=0970106), [All aircraft, 12 cases](https://openairdocs.org/ntsb-events/450/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Ayres S2R-T34, 8 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0970106), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis Before the aerial application flight, the 510-gallon hopper was loaded with 450 gallons of a chemical mixture. While on his second spray pass, the pilot noticed the chemical mixture was reacting and foaming over and out the hooper vent. He climbed the airplane out of his second pass and noticed chemical foaming out of the overflow vent. He looked forward and observed the chemical reacting violently, and it began to emit from the hopper lid. The windshield became fully obscured with foam, and the pilot was unable to see anything outside the airplane. The pilot opened the window in attempt to determine his altitude when the airplane impacted terrain in a wings-level attitude. The airplane skidded on the terrain and came to rest upright. A postaccident examination of the airplane did not reveal any mechanical anomalies. A jar test of the chemical mixture used in the hopper was not performed by the pilot or the ground loading operations personnel as recommended by the manufacturer of one of the chemicals used. In addition, the technical sheet for one of the chemicals used contained a caution about a chemical foaming reaction when mixing it with other chemicals, one of which was also in the hopper. Due to the pilot’s view being obscured from foam originating from the hopper, the pilot was unable to maintain control and clearance from the terrain during the flight. ## Factual narrative On June 21, 2021, about 1615 central daylight time, an Ayres S2R-T34 airplane, N4328P, was involved in an accident near Leoti, Kansas. The commercial pilot sustained minor injuries, and the airplane sustained substantial damage. The airplane was being operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. According to the pilot, the 510-gallon hopper was loaded with 10 ounces of FoamBuster Max, 62.5 gallons of Buccaneer 5 Extra herbicide, 300 gallons of Kugler KQ-XRN fertilizer, and 87.5 gallons of water (450 gallons total mixture). While on his second spray pass, the pilot noticed the chemical mixture was foaming over and through the hooper vent. He climbed the airplane out of his second pass and noticed chemical foaming out of the overflow vent. He then looked forward and observed the chemical reacting violently, and it began to emit from the hopper lid. The windshield became fully obscured with foam, and the pilot was unable to see anything outside the airplane. The pilot opened the window in attempt to determine his altitude when the airplane impacted terrain in a wings-level attitude. The airplane skidded on the terrain and came to rest upright. The airplane sustained substantial damage to both wings and the fuselage. A postaccident examination of the airplane did not reveal any mechanical anomalies that would have precluded normal operation. The pilot reported he had recently replaced the hopper lid seal but could not recall the date. A jar test of the chemical mixture in the hopper was not performed by the pilot or the ground loading operations personnel. The Kugler KQ-XRN technical sheet precautions stated, in part, “Use caution when mixing KQ-XRN with phosphate, sulfur, humic acid and products containing glyphosate, a chemical foaming reaction may occur. Kugler recommends always performing a simple jar test when mixing KQ-XRN with any pesticides and fertilizers.” According to the Buccaneer 5 Extra active ingredients, the herbicide contains 53.8% glyphosate. ## Aircraft - Registration: [N4328P](https://openairdocs.org/deregistered/N4328P-2023-04-18), registration cancelled 2023-04-18, S/N T41-154DC, built 1991 (OpenAirDocs) - Reported make and model: AYRES CORPORATION S2R-T34 - Registry model: [Ayres S2R-T34](https://openairdocs.org/model/ayres-s2r-t34) (registry code 0970106) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52032, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: T41-154DC - Year built: 1991 - Engines: P&W PT6A SER 750 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Ag Solutions LLC - Registered owner: Ag Solutions LLC - Airworthiness certificate: Special, Restricted (Special) - Destination: Same as departure - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; injuries: minor; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; seat: center; restraint: 4-point; flight hours: 2,300 total ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 48 °F - Altimeter: 30.14 inHg - Observed at: KTQK, 22 nm away - METAR: KTQK 212115Z AUTO 34010KT 10SM 26/09 A3014 RMK AO2 T02560095 ## 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 20210621006889A](https://openairdocs.org/incident/20210621006889A), Jun 21, 2021: Ayres Corporation S2R-T34, Leoti, KS, Substantial damage. On the date of the accident the pilot arrived at the field he was to spray. He lined up with a saved pattern on a field that he had partially sprayed on… ## Docket (6 files) The files NTSB released with the investigation on September 30, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103313. 18.0 MB in all. - Pilot statement (item 1, PDF, 1 page, 117 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12794066&FileExtension=pdf&FileName=Pilot%20Statement_Redacted-Rel.pdf - FAA record of conversation (item 2, PDF, 1 page, 162 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12794262&FileExtension=pdf&FileName=ROC%20FAA-Rel.pdf - Flight chemical load (item 3, PDF, 1 page, 12.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12793380&FileExtension=pdf&FileName=Accident%20Flight%20Chemical%20Load-Rel.pdf - Fertilizer precaution (item 4, PDF, 2 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12794252&FileExtension=pdf&FileName=KQ-XRN%20Precautions-Rel.pdf - Herbicide information (item 5, PDF, 1 page, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12793877&FileExtension=pdf&FileName=Herbicide%20Information-Rel.pdf - Photo array (item 6, PDF, 2 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12793744&FileExtension=pdf&FileName=Photo%20Array-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.