# NTSB CEN10LA279: Thunderbird TOP DOG UL, N2574V, Luling, TX, May 29, 2010 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: May 29, 2010, 08:25 local (13:25 UTC) - Place: Luling, TX - Coordinates: 29.728332, -97.659164 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=29.7283&lon=-97.6592&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report October 3, 2011 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 76173 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN10LA279 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76173/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76173 - Page: https://openairdocs.org/ntsb/CEN10LA279 ## Probable cause Poor engine performance due to the modified engine parameters and installation of the fuel nozzles which produced a lean fuel condition resulting in decreased aircraft performance and subsequent impact with the trees. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Power plant](https://openairdocs.org/ntsb-findings/01057100): Aircraft › Aircraft power plant · Incorrect service/maintenance; cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-findings/01057100/cases.md?model=05902V4), [All aircraft, 198 cases](https://openairdocs.org/ntsb-findings/01057100/cases.md) - [Aircraft capability: takeoff distance](https://openairdocs.org/ntsb-findings/01061025): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-findings/01061025/cases.md?model=05902V4), [All aircraft, 67 cases](https://openairdocs.org/ntsb-findings/01061025/cases.md) - [Performance/control parameters: powerplant parameters](https://openairdocs.org/ntsb-findings/01062050): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-findings/01062050/cases.md?model=05902V4), [All aircraft, 81 cases](https://openairdocs.org/ntsb-findings/01062050/cases.md) - [Engine fuel and control: fuel injector nozzle](https://openairdocs.org/ntsb-findings/01057313): Aircraft › Aircraft power plant · Incorrect use/operation; cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-findings/01057313/cases.md?model=05902V4), [All aircraft, 20 cases](https://openairdocs.org/ntsb-findings/01057313/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-events/040/sequence.md?model=05902V4), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05902V4), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Takeoff: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-events/300/sequence.md?model=05902V4), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Takeoff: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Thunderbird TOP DOG UL, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=05902V4), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Analysis While attempting to take off, the airplane impacted a tree line and terrain. A postaccident engine examination revealed signs of inadequate maintenance, including finger-tight spark plugs, an obstructed air vent line, and evidence of water intrusion in the carburetor bowls. An engine test run determined that full power could not be achieved with the combination of installed engine components. The installed main jets produced a lean fuel condition that resulted in a loss of engine power before maximum rpm could be achieved. After replacing the components with stock components, the engine produced normal engine performance. ## Factual narrative On May 29, 2010, approximately 0825 central daylight time, a Thunderbird Aviation Top Dog weight-shift control airplane, N2574V, impacted terrain during an attempted takeoff from the Carter Memorial Airport (T91), Luling, Texas. The sport pilot, the sole occupant, was seriously injured. The airplane's fuselage structure and wing surface were substantially damaged. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The flight was originating at the time of the accident. There were no witnesses to the accident. The pilot could not recall the accident sequence and did not provide any statement. A review of the wreckage conducted by an inspector from the Federal Aviation Administration revealed no preimpact anomalies. The airplane was powered by a Rotax 503, twin cylinder, dual carbureted, two stroke engine, rated for 50 hp at 6,800 rpm. The engine was removed and sent to the engine manufacturer in Vernon, Canada, where an examination was conducted under the auspices of the Canadian Transportation Safety Board (TSB). All spark plugs were found to be finger-tight, signatures of water intrusion were detected in one carburetor float bowl, and the other carburetor bowl contained fuel tainted with an unknown substance. The engine was mounted on a test stand complete with clean fuel. The spark plugs were tightened and the air filter was replaced. The engine was turned over via a pull starter and started on the first pull. The engine operated normally at idle rpm, but when advanced towards maximum rpm, would only achieve 5,730 rpm. Repeated attempts confirmed that the engine could not reach maximum rpm. Further examination revealed that the engine spark plugs and carburetor main jets were not per the manufacture's specifications. After replacing them with components recommended by the manufacture, the engine was able to achieve 6,230 rpm, the maximum rpm expected for the conditions present during the test. According to the manufacturer, the carburetor main fuel jets that were installed at the time of the accident provided a lean mixture that would not allow the engine to reach its rated power. ## Aircraft - Registration: [N2574V](https://openairdocs.org/deregistered/N2574V-2017-05-22), registration cancelled 2017-05-22, S/N TXA01TDA, built 2002 (OpenAirDocs) - Reported make and model: THUNDERBIRD AVIATION TOP DOG UL - Registry model: [Thunderbird TOP DOG UL](https://openairdocs.org/model/thunderbird-top-dog-ul) (registry code 05902V4) (OpenAirDocs) - Registry engine: [Rotax 503 DCDI](https://openairdocs.org/engine/rotax-503-dcdi) (registry code 55566, 2 cycle) (OpenAirDocs) - Category: Weight-shift - Serial number: TXA01TDA - Engines: ROTAX 503 DCDI 52 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Comer Kenton R - Registered owner: Comer Kenton R - Airworthiness certificate: Special, Experimental light sport (Special) - Departed: KT91, Luling, TX - Destination: KT91, Luling, TX - Airport: KT91, Carter Memorial Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; injuries: serious; private, sport pilot; airplane ratings: single-engine land; medical: sport pilot; seat: front ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Temperature: 77 °F, dew point 66 °F - Altimeter: 29.85 inHg - Observed at: KHYI, 14 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 20100529039609A](https://openairdocs.org/incident/20100529039609A), May 29, 2010: Thunderbird TOP DOG UL, Luling, TX, Substantial damage. On July 21, 2010 at 09:40 am, I had a phone interview with kenton comer. He is currently in a rehabilitation hospital in st louis due to the injuries received… ## Docket (3 files) The files NTSB released with the investigation on July 21, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76173. 1.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1: Not obtained (item 1, .PDF, 14 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40344866&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1%3A%20Not%20obtained-Master.PDF - Other Pertinent Forms and Reports: Excerpt from Rotax report (item 2, .PDF, 120 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40344868&FileExtension=.PDF&FileName=Other%20Pertinent%20Forms%20and%20Reports%3A%20Excerpt%20from%20Rotax%20report-Master.PDF - Photo (item 3, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40350056&FileExtension=.PDF&FileName=Photo-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.