# NTSB CEN19FA278: Grumman G164, N3631Z, Hays, KS, August 20, 2019 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: August 20, 2019, 09:15 local (14:15 UTC) - Place: Hays, KS - Coordinates: 38.726112, -99.34111 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.7261&lon=-99.3411&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report May 19, 2020 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA - NTSB case key (mKey): 100100 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN19FA278 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100100/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100100 - Page: https://openairdocs.org/ntsb/CEN19FA278 ## Probable cause The pilot's exceedance of the airplane's critical angle of attack, which resulted in an aerodynamic stall. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Schweizer G-164B, 2 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=8059055), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Schweizer G-164B, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=8059055), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Schweizer G-164B, 7 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=8059055), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/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: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) (defining event); cases with it: [Schweizer G-164B, 2 cases](https://openairdocs.org/ntsb-events/241/sequence.md?model=8059055), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Schweizer G-164B, 13 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=8059055), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Post-impact: Fire/smoke (post-impact)](https://openairdocs.org/ntsb-events/170); cases with it: [Schweizer G-164B, 2 cases](https://openairdocs.org/ntsb-events/170/sequence.md?model=8059055), [All aircraft, 354 cases](https://openairdocs.org/ntsb-events/170/sequence.md) ## Analysis The pilot was performing an agricultural application flight, and the airplane was observed departing a private airstrip to the east toward a field west of the airstrip. The airplane impacted terrain in a steep, nose-down attitude. A postimpact fire ensued. There were no witnesses to the accident. Impact signatures and twisting of the wreckage were indicative of a nose-low spin, consistent with an aerodynamic stall . Flight control continuity could not be verified due to fire damage, but no anomalies were noted with the airframe and engine that would have precluded normal operation. The pilot's toxicology tests results showed no drug or alcohol use. Thus, it is likely that aerodynamic stall resulted from the pilot allowing the airplane to exceed its critical angle of attack during a turn. ## Factual narrative On August 20, 2019, at 0915 central daylight time, a Grumman-Schweizer G164-B airplane, N3631Z, impacted terrain near Hays, Kansas. The commercial pilot was fatally injured, and the airplane was destroyed by impact forces and postimpact fire. The airplane was owned and operated by Werth Aerial Spraying Inc. as a Title 14 Code of Federal Regulations Part 137 agricultural application flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which originated from the operator's private airstrip. According to a family member, the purpose of the flight was to apply chemicals to a neighbor's field west of the pilot's private airstrip. The family member observed the airplane departing the airstrip to the east and then turned away from the airplane. She did not see the airplane after it departed or for the remainder of the flight. The airplane impacted terrain 0.7 mile northeast of the airstrip. There were no witnesses to the accident. The District Coroner, 23rd Judicial District of Kansas, performed an autopsy on the pilot. His cause of death was thermal injuries and carbon monoxide inhalation. Toxicology testing performed at the Federal Aviation Administration Forensic Sciences Laboratory was negative for ethanol, carbon monoxide, and all tested drugs. The airplane impacted a gravel road that was oriented east to west and an adjacent ditch. All wreckage was located within about 50 ft of the initial impact point, and ground scars were oriented on a 292° heading. The wings were oriented along an east-west direction, and the top of the wings faced south. The metal tube frame of the fuselage and empennage were oriented toward the north-northwest with the vertical and horizontal stabilizers rotated to the west. The engine was separated from the fuselage and located abeam the tail. The airplane's attitude at impact and impact angle could not be determined from the available evidence, but the damage to the wreckage and the orientation of the wreckage in relation to the initial impact point were consistent with an impact at a steep angle. A post-impact fire consumed most of the fuselage, cockpit, and inboard sections of the left and right wings. Flight control continuity was established from the ailerons, rudder, and elevators to the cockpit. Control continuity could not be established within the cockpit due to fire damage to the flight controls. The engine had separated from the main wreckage The propeller and throttle control levers were found in the full forward position. The mixture control lever was found near the full aft position. Engine control cables were continuous from their respective control levers to the engine firewall. The control cables terminated forward of the engine firewall in a manner consistent with overload. A teardown of the engine was performed, and no anomalies were found that could have led to a loss of engine power. The propeller spinner was removed, and both propeller blades were foundto be in a low pitch position. One blade was bent aft about 90° near the midpoint of the blade. Gouges were present on the leading edge of the blade. The other blade was straight and exhibited leading edge gouging and polishing and chordwise scratches. Examination of the airframe and engine revealed no anomalies that would have precluded normal operation. ## Aircraft - Registration: [N3631Z](https://openairdocs.org/deregistered/N3631Z-2021-05-28), registration cancelled 2021-05-28, S/N 765B, built 1985 (OpenAirDocs) - Reported make and model: Grumman G164 (B) - Registry model: [Schweizer G-164B](https://openairdocs.org/model/schweizer-g-164b) (registry code 8059055) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 765B - Year built: 1985 - Airframe hours: 2616 - Engines: Pratt and Whitney R-985-AN-14B reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Aerial application, Part 137 - Operator: Werth Aerial Spraying Inc - Registered owner: Werth Aerial Spraying Inc - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, April 6, 2019 - Departed: Hays, KS - Destination: Hays, KS - Airport: N/A, Werth Private Airstrip ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 70; injuries: fatal; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; seat: single; toxicology performed; flight hours: 18,616 total ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 70 °F - Altimeter: 29.92 inHg - Observed at: KHYS, 9 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 20190820013909A](https://openairdocs.org/incident/20190820013909A), Aug 20, 2019: Schweizer Aircraft Corp G-164B, Hays, KS, Destroyed, 1 fatal. At approximately 09:16 am on August 20th, 2019 a single pilot Grumman ag cat model G-164B serial number 765B aerial application aircraft took off east from a… ## Docket (9 files) The files NTSB released with the investigation on March 25, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100100. 5.4 MB in all. - Record of Conversation - Pilot's Wife (item 1, .PDF, 52 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481539&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20Pilot%27s%20Wife-Master.PDF - Engine Examination Report (item 2, .PDF, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481540&FileExtension=.PDF&FileName=Engine%20Examination%20Report-Master.PDF - Maintenance Records (item 3, .PDF, 547 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481541&FileExtension=.PDF&FileName=Maintenance%20Records-Master.PDF - Toxicological Report (item 4, .PDF, 151 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481542&FileExtension=.PDF&FileName=Toxicological%20Report-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 5, .PDF, 208 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481543&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Maps or Charts of Accident Area (item 6, .PDF, 504 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481544&FileExtension=.PDF&FileName=Maps%20or%20Charts%20of%20Accident%20Area-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 7, .PDF, 333 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481545&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Master.PDF - Propeller Email (item 8, .PDF, 132 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481546&FileExtension=.PDF&FileName=Propeller%20Email-Master.PDF - Photos (item 9, .PDF, 874 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481547&FileExtension=.PDF&FileName=Photos-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.