# NTSB CEN21LA092: Sonex Tailwheel, N935EK, Burleson, TX, December 19, 2020 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 3 · Limited · Final report - Date: December 19, 2020, 14:30 local (20:30 UTC) - Place: Burleson, TX · 76028 - Coordinates: 32.56537, -97.30837 - Nearby events: https://openairdocs.org/map.md?lat=32.5654&lon=-97.3084&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 102435 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA092 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102435/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102435 - Page: https://openairdocs.org/ntsb/CEN21LA092 ## Probable cause A total loss of engine power due to engine seizure. Contributing to the accident was the pilot decision not to orbit the airport, as originally planned. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Kirkpatrick Earl L SONEX - TAILWHEEL, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=05637S8), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Fluids: oil](https://openairdocs.org/ntsb-findings/01071020): Aircraft › Fluids/misc hardware · Unknown/Not determined; cases with it: [Kirkpatrick Earl L SONEX - TAILWHEEL, 1 case](https://openairdocs.org/ntsb-findings/01071020/cases.md?model=05637S8), [All aircraft, 174 cases](https://openairdocs.org/ntsb-findings/01071020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Kirkpatrick Earl L SONEX - TAILWHEEL, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05637S8), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Initial climb: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Kirkpatrick Earl L SONEX - TAILWHEEL, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05637S8), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot and builder of the airplane was conducting the airplane’s first flight. The pilot contacted the tower controller and requested to orbit the airport for 30 minutes at 3,500 ft. Shortly after departure, the pilot reported that he was unable to climb and needed to return to the airport. The pilot reported that he had a “sick engine,” and he was “just trying to make the field.” The controller reported to the pilot that smoke appeared to be coming from the engine. Automatic Dependent Surveillance–Broadcast (ADS-B) data revealed the airplane departed from the airport, turned, and flew south for about 2 miles before it turned north back to the airport. During the subsequent forced landing, the airplane impacted powerlines and terrain and came to rest inverted about 1 mile south of the airport. During the engine examination oil was present on the dipstick. The oil filter was cut open and fine metal pieces/powder were observed on the filter element, and small metal pieces were observed in the engine’s oil filter port. The engine was seized and could not be rotated by hand. The engine was not dissembled further, and the source of the metal filings was not determined. The loss of engine power was attributed to the seizure of the engine; however, the reason for the engine seizure could not be determined. Investigators were unable to determine why the pilot did not stay over the airport and orbit as originally requested. ## Factual narrative On December 19, 2020, about 1430 central standard time, a Sonex light sport airplane, N935EK, was substantially damaged when it was involved in an accident near Burleson, Texas. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations 91 personal flight. A witness reported that the airplane had been built as a kit and this was the airplane’s first flight. A review of air traffic control information revealed that the pilot contacted the Spinks Airport (FWS) controller and requested to orbit the airport for 30 minutes at 3,500 ft. Shortly after departure, the controller asked if the pilot needed any assistance. The pilot reported that he was unable to climb and needed to return to the airport. The controller cleared the pilot direct to the airport and to land on runway 35. The pilot reported that he had a “sick engine,” and he was “just trying to make the field.” The controller reported to the pilot that smoke appeared to be coming from the engine. A review of Automatic Dependent Surveillance–Broadcast (ADS-B) data revealed the airplane departed from FWS, turned, and flew south for about 2 miles before it turned north back to the airport. (see Figure 1.) During the forced landing, the airplane impacted powerlines and terrain and came to rest inverted near a business about 1 mile south of the airport. Figure 1: Airplane’s Flight Track An engine examination revealed a light film of oil on the underside of the airplane’s fuselage. No evidence of an inflight fire was observed. A visual inspection of the engine did not reveal any obvious discrepancies in the engine or an avenue for engine oil to escape. An attempt to rotate the engine by turning the propeller by hand revealed that the engine was seized. The engine was equipped with a remote oil filter mounted on the firewall. Two oil lines from the oil filter adapter ran to the front of the engine where the engine’s oil pump was located; one line ran from the “inlet” side of the oil filter adapter to one side the oil pump. On the other side of the pump, an oil line ran to the “outlet” side of the oil filter adapter. The oil filter was removed and cut open; small, fine metal pieces/powder were in the oil and on the filter element. Small metal pieces were seen when looking into the engine’s oil filter port and oil was present on the dip stick. The engine was not dissembled further and the source of the metal filings was not determined. The airplane was equipped with a Dynon EMS D10 engine monitoring system. Review of recorded data did not reveal any information that could be correlated to the accident flight. The airplane’s hour meter showed 213.9 hours which was not consistent with the accident flight being the first flight for the airplane. ## Aircraft - Registration: [N935EK](https://openairdocs.org/deregistered/N935EK-2021-10-02), registration cancelled 2021-10-02, S/N 1617, built 2019 (OpenAirDocs) - Reported make and model: Sonex Tailwheel - Registry model: [Kirkpatrick Earl L SONEX - TAILWHEEL](https://openairdocs.org/model/kirkpatrick-earl-l-sonex-tailwheel) (registry code 05637S8) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 1617 - Year built: 2019 - Engines: AeroVee 80 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, September 18, 2020 - Airport: FWS, Fort Worth Spinks Airport - Equipment: ADS-B, Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 85; injuries: fatal; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; seat: left; restraint: 4-point; toxicology performed; flight hours: 2,195 total ## Weather - Conditions: Visual (VMC), Day - Wind: 300° at 9 knots - Visibility: 10 statute miles - Temperature: 57 °F, dew point 46 °F - Altimeter: 30.08 inHg - Observed at: KFWS, 1 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 20201219020619A](https://openairdocs.org/incident/20201219020619A), Dec 19, 2020: Kirkpatrick Earl L SONEX - TAILWHEEL, Burleson, TX, Substantial damage, 1 fatal. On December 19, 2020 at approximately 1435 CST, [privacy data omitted], an experimental sonex, crashed while on an engine maintenance flight approximately 1… ## Docket (8 files) The files NTSB released with the investigation on April 6, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102435. 40.2 MB in all. - Air traffic control (item 1, PDF, 1 page, 119 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12080777&FileExtension=pdf&FileName=ATC-Rel.pdf - Witness (item 2, PDF, 2 pages, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12086010&FileExtension=pdf&FileName=Witness_Redacted-Rel.pdf - Maintenance records (extract) (item 3, PDF, 13 pages, 18.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12080588&FileExtension=pdf&FileName=Logbook%20Entries%20(Extract)_Redacted-Rel.pdf - Airplane examination (item 4, PDF, 2 pages, 157 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12079311&FileExtension=pdf&FileName=Examination%20Summary%20--Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 5, PDF, 1 page, 576 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12085140&FileExtension=pdf&FileName=signed%20NTSB%20wreckage%20release%20form%20-%20CEN21LA092_Redacted-Rel.pdf - Photos (item 6, PDF, 11 pages, 19.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12079321&FileExtension=pdf&FileName=Photo%201-Rel.pdf - Toxicological report (item 7, PDF, 1 page, 189 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12084061&FileExtension=pdf&FileName=Pilot%20Tox_Redacted-Rel.pdf - Adsb data (item 8, CSV, 204 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13169970&FileExtension=csv&FileName=20201219_ACF8AA_442864614_ADSB-Rel.csv 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.