# NTSB CEN21LA351: Cozy Mark IV, N1361S, Rushville, NE, August 2, 2021 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Final report - Date: August 2, 2021, 15:54 local (21:54 UTC) - Place: Rushville, NE · Open grass field. - Coordinates: 42.846558, -102.51894 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.8466&lon=-102.5189&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: Serious injuries - Injuries: 2 serious - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA Lincoln FSDO, Lycoming Engines - NTSB case key (mKey): 103626 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA351 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103626/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103626 - Page: https://openairdocs.org/ntsb/CEN21LA351 ## Probable cause A total loss of engine power due to an obstruction of airflow to the engine as a result of the landing brake being deployed in flight. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=05602ZF), [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md) - [Temp/humidity/pressure: high temperature](https://openairdocs.org/ntsb-findings/03031015): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-findings/03031015/cases.md?model=05602ZF), [All aircraft, 30 cases](https://openairdocs.org/ntsb-findings/03031015/cases.md) - [Indicating/recording systems: instrument panel ](https://openairdocs.org/ntsb-findings/01023110): Aircraft › Aircraft systems · Not installed/available (probable cause); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-findings/01023110/cases.md?model=05602ZF), [All aircraft, 22 cases](https://openairdocs.org/ntsb-findings/01023110/cases.md) - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=05602ZF), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=05602ZF), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Capability exceeded (probable cause); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=05602ZF), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/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: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05602ZF), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05602ZF), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=05602ZF), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) - [Landing: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Sligar Larry H COZY MK IV, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=05602ZF), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Analysis The pilot reported that after takeoff in the experimental airplane, he noticed that all four cylinder head temperatures (CHT) were higher than they should have been as indicated on the engine monitoring device. He noticed that the CHT never stabilized and never decreased in temperature after the takeoff. The pilot attempted to reduce the high CHT with the throttle and mixture and the CHT kept rising. The pilot decided to return to the departure airport. During the flight back to the airport, the CHT still kept rising, and the engine ceased producing power. The pilot maneuvered the airplane for a forced landing to an open grass field surrounded by rolling prairie and trees. During the forced landing, the nose wheel and the main landing gear collapsed, and the airplane came to rest on the fuselage. Postaccident examination of the landing brake actuator revealed that it likely failed due to compressive overload on the actuator while positioned in the fully extended position. The actuator extension tube was found positioned about midway between the extended and retracted positions The flanges on the nut were fractured in overstress consistent with a compression overload. The brush that is normally attached to the nut above the flange was found in the fully retracted position, indicating that after the nut flanges fractured, the extension tube likely moved to the fully retracted position, pushing the brush along with it. Based on the examination of the landing brake actuator, the landing brake was likely fully extended at the time of the accident. The extended landing brake would have blocked airflow to the engine, causing the engine to overheat and cease producing power. If a cockpit indication system for the landing brake had been installed, the pilot likely could have known the status of the landing brake during the flight and thus retract it. It is likely that the pilot either forgot to retract the landing brake after the previous landing or the pilot may have inadvertently activated it before the loss of engine power. Based on the available evidence it could not be determined exactly when the landing brake was deployed. ## Factual narrative On August 2, 2021, about 1554 mountain daylight time, a Cozy Mark IV airplane, N1361S, sustained substantial damage when it was involved in an accident near Rushville, Nebraska. The commercial pilot and passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that after takeoff in the experimental airplane, he noticed that all four CHT were higher than they should have been as indicated on the engine monitoring device. He noticed that the CHTs never stabilized and never decreased in temperature after the takeoff. The outside air temperature was 91° F, and the airplane was traveling about 130 kts after the takeoff. The pilot attempted to reduce the high CHTs with the throttle and mixture and the CHTs kept rising. The pilot decided to return to the departure airport. During the flight back to the airport, the CHTs still kept rising, and the engine ceased producing power. The pilot maneuvered the airplane for a forced landing to an open grass field surrounded by rolling prairie and trees. During the forced landing, the nose wheel and the main landing gear collapsed from impacting the field, and the airplane came to rest on the fuselage. The pilot and passenger were able to egress from the airplane without further incident. The airplane sustained substantial damage to the composite fuselage. The pilot reported the airplane was “about topped off” with fuel prior to the cross-country flight and there was 44 gallons of 100LL fuel onboard during the takeoff. The airframe was equipped with a parachute, which was not activated during the emergency sequence. Postaccident examination of the airplane established flight control continuity and airframe to engine control continuity. The landing brake, also called the airbrake (located on the bottom of the fuselage, forward of the engine) was examined. Power was turned on to test functionality from the cockpit switch. The landing brake would not fully extend. Full extension is about a 45°angle downwards away from the fuselage. Impact damage such as scraping was observed on the underside of the landing brake. The actuator extension tube had play in it when the landing brake door was moved by hand. The airplane, which was classified as experimental, was not equipped with a landing brake indicator system in the cockpit, nor was it required to be. Postaccident examination of the landing brake actuator at the National Transportation Safety Board Materials Laboratory found the extension tube was positioned about midway between the extended and retracted positions. The nut inside the actuator was found positioned against the lower mechanical stop in the fully extended position. The flanges on the nut were found fractured. No evidence of any preexisting damage or cracking was observed. The brush that is normally attached to the nut above the flange was found in the fully retracted position. Examination of the engine revealedinternal engine continuity and no signs of a fire. The plastic thrust buttons on the rocker shafts were found melted. An exemplar owner’s manual from a Cozy Mark IV discusses the landing brake and states in part: A drag device is used to allow a steeper approach and to provide more deceleration in the flare. This belly-mounted brake is deployed by an electric switch on the lower center instrument panel. It is normally extended on final approach after gear extension and left down until after landing. Maximum allowable speed with the airbrake down is 90 KIAS. The brake does not affect stability, canard stall speed, or canard stall characteristics, and has only a mild effect on pitch trim. The brake significantly interferes with the airflow passing into the engine cooling NACA duct and engine temperatures will likely exceed safe limits if the throttle is set above 1,500 RPM with the brake extended. ## Aircraft - Registration: [N1361S](https://openairdocs.org/aircraft/N1361S), registered now, S/N 0074, built 1997 (OpenAirDocs) - Reported make and model: Cozy Mark IV (NO SERIES) - Registry model: [Sligar Larry H COZY MK IV](https://openairdocs.org/model/sligar-larry-h-cozy-mk-iv) (registry code 05602ZF) (OpenAirDocs) - Registry engine: [Lycoming 0-360-A1D](https://openairdocs.org/engine/lycoming-0-360-a1d) (registry code 41504, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 0074 - Year built: 1997 - Airframe hours: 854 - Engines: Lycoming Engines O-360-EXP 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, March 1, 2021 - Departed: GRN, Gordon, NE - Destination: LND, Lander, WY - Equipment: Airframe parachute, ADS-B, Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 63; injuries: serious; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review April 26, 2020; seat: left; restraint: 4-point; flight hours: 788 total, 300 in this make and model, 727 as pilot in command, 20 in the last 90 days, 11 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 9 statute miles - Lowest ceiling: none - Temperature: 95 °F, dew point 39 °F - Altimeter: 30.08 inHg - Observed at: KIEN, 10 nm away - METAR: KIEN 022152Z AUTO VRB06KT 9SM CLR 35/04 A3008 RMK AO2 SLP151 T03500044 $ ## 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 20210802018569A](https://openairdocs.org/incident/20210802018569A), Aug 2, 2021: Sligar Larry H COZY MK IV, Gordon, NE, Substantial damage. During climb out from grn the aircraft's engine overheated and seized. The aircraft was substantially damaged during the following emergency landing on hilly… ## Docket (11 files) The files NTSB released with the investigation on February 24, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103626. 27.6 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14918472&FileExtension=pdf&FileName=NTSB%20Form%206120_1%20Redacted-Rel.pdf - Pilot - memorandum of record (item 2, PDF, 1 page, 67 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14934871&FileExtension=pdf&FileName=CEN21LA351%20Pilot%20MOR-Rel.pdf - State of Nebraska - accident report and photographs (item 3, PDF, 8 pages, 9.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14919147&FileExtension=pdf&FileName=State%20of%20Nebraska%20-%20Accident%20Report%20and%20Photographs%20Redacted-Rel.pdf - Accident photographs (item 4, PDF, 12 pages, 4.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14918632&FileExtension=pdf&FileName=Accident%20Photographs-Rel.pdf - NTSB airframe and engine examination report (item 5, PDF, 6 pages, 167 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14918482&FileExtension=pdf&FileName=CEN21LA351%20NTSB%20Airframe%20and%20Engine%20Examination%20Report-Rel.pdf - Airflow performance fuel control unit examination report (item 6, PDF, 4 pages, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14918716&FileExtension=pdf&FileName=CEN21LA351%20Airflow%20Performance%20Fuel%20Control%20Unit%20Examination%20Report%20Redacted-Rel.pdf - Materials laboratory factual report 22-087 (item 7, PDF, 12 pages, 12 photos, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14737280&FileExtension=pdf&FileName=22-087-Rel.pdf - NTSB vehicle recorders laboratory report (item 8, PDF, 3 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14918726&FileExtension=pdf&FileName=CEN21LA351%20NTSB%20Vehicle%20Recorders%20Laboratory%20Report-Rel.pdf - Most recent airframe, engine, and propeller maintenance work (item 9, PDF, 3 pages, 5.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14918966&FileExtension=pdf&FileName=Most%20Recent%20Airframe,%20Engine,%20and%20Propeller%20Maintenance%20Work%20Redacted-Rel.pdf - Exemplar cozy mk iv owner's manual N83MZ - landing brake information (item 10, PDF, 2 pages, 452 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14918427&FileExtension=pdf&FileName=Exemplar%20Cozy%20MK%20IV%20Owner%27s%20Manual%20N83MZ%20-%20Landing%20Brake%20Information-Rel.pdf - NTSB party member form - Lycoming engines (item 11, PDF, 1 page, 231 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14934861&FileExtension=pdf&FileName=NTSB%20Party%20Member%20Form%20-%20Lycoming%20Engines%20Redacted-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.