# NTSB CEN18LA042: Motley Gary W Zenith CH750 Cruzer, N956GM, Louviers, CO, November 27, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 27, 2017, 15:20 local (22:20 UTC) - Place: Louviers, CO - Coordinates: 39.462223, -105.007774 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.4622&lon=-105.0078&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report November 15, 2018 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 96397 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN18LA042 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96397/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96397 - Page: https://openairdocs.org/ntsb/CEN18LA042 ## Probable cause The engine’s excessive cylinder head temperatures and the subsequent seizing of the engine, which resulted from an engine control unit that caused the engine’s fuel-air mixture to be too lean. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng liquid cooling](https://openairdocs.org/ntsb-findings/01058570): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Motley Gary W ZENITH CH750 CRUZER, 1 case](https://openairdocs.org/ntsb-findings/01058570/cases.md?model=05636F4), [All aircraft, 17 cases](https://openairdocs.org/ntsb-findings/01058570/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Motley Gary W ZENITH CH750 CRUZER, 1 case](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=05636F4), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Motley Gary W ZENITH CH750 CRUZER, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05636F4), [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: [Motley Gary W ZENITH CH750 CRUZER, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05636F4), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Motley Gary W ZENITH CH750 CRUZER, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05636F4), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The commercial pilot was conducting a flight in an experimental airplane to assess engine performance after installing a replacement engine control unit (ECU) with updated programming. During the flight, the engine monitor provided an alert regarding a high engine coolant temperature. Shortly afterward, the engine seized. The pilot attempted two engine restarts, including a complete reboot of the ECU, without success. The pilot made a forced landing in an open field. The airplane struck a barbed wire fence, causing damage to the nose landing gear, engine cowling, right wing strut, and right wing skin. Also, the pilot noticed that the coolant expansion tank had overfilled due to overheating. A postaccident examination revealed that the ECU had caused the engine fuel-air mixture to be too lean, resulting in excessive cylinder head temperatures, which caused the engine to seize. The excessive cylinder head temperatures also resulted in the unseating of the head gasket, which pressurized the coolant jacket and evacuated engine coolant overboard. Coolant was found in three of the four cylinders, and oil was mixed in the coolant under the thermostat, resulting in the rapid rise of coolant temperature. ## Factual narrative On November 27, 2017, about 1520 mountain standard time, the pilot of a Zenith CH750 Cruzer, N956GM, made a forced landing near Louviers, Colorado, after the engine lost power. The pilot was not injured, but the airplane was substantially damaged. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. The local flight originated from Rocky Mountain Metropolitan Airport (BJC), Broomfield, Colorado, approximately 1440. The purpose of the flight was to assess engine performance after the pilot had installed a replacement Engine Control Unit (ECU) with updated programming. The pilot flew to his phase 1 flight area near Louviers and was performing autopilot testing. The engine monitor alerted him to high engine coolant temperature. He reduced power and turn back towards the airport. Engine RPMs decreased and engine temperature increased. Fuel and oil pressures stayed within normal limits. Shortly thereafter, the engine seized and the propeller stopped rotating. The pilot attempted two engine restarts, including a complete rebooting of the ECU, without success. The pilot made a forced landing in an open field. The airplane struck an unseen barbed wire fence, collapsing the nose landing gear and crushing the engine cowling. The right-wing strut was bent, and there was some wing skin damage. The pilot noticed the coolant expansion tank had overfilled due to the overheating. The pilot later examined the engine and found that the ECU had run "the engine too lean, resulting in excessive cylinder head temperatures. This resulted in the unseating of the head gasket, which pressurized the coolant jacket and evacuated engine coolant overboard." The pilot added that he "found [coolant] in three of the four cylinders, oil was mixed in the coolant under the thermostat…[resulting] in the rapid rise of coolant temp and stoppage of the engine." ## Aircraft - Registration: [N956GM](https://openairdocs.org/aircraft/N956GM), registered now, S/N C75-10359, built 2017 (OpenAirDocs) - Reported make and model: MOTLEY GARY W ZENITH CH750 CRUZER (NO SERIES) - Registry model: [Motley Gary W ZENITH CH750 CRUZER](https://openairdocs.org/model/motley-gary-w-zenith-ch750-cruzer) (registry code 05636F4) (OpenAirDocs) - Registry engine: [Viking 130 GDI](https://openairdocs.org/engine/viking-130-gdi) (registry code 63999, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: C75-10359 - Year built: 2017 - Airframe hours: 32 - Engines: VIKING 130GDI 130 horsepower reciprocating - Damage: Substantial damage - Flight: Flight test, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, September 17, 2017, 32 hours before - Departed: BJC, BROOMFIELD, CO - Destination: BJC, BROOMFIELD, CO - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; injuries: none; commercial; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: basicmed, without waivers/limitations; last flight review May 13, 2017; seat: left; restraint: 3-point; flight hours: 3,100 total, 32 in this make and model, 3,100 as pilot in command, 39 in the last 90 days, 10 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 16 knots, gusting 27 - Visibility: 10 statute miles - Lowest ceiling: 22,000 ft broken - Temperature: 77 °F, dew point 10 °F - Altimeter: 29.65 inHg - Observed at: APA, 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 20171127022139A](https://openairdocs.org/incident/20171127022139A), Nov 27, 2017: Zenith CH750, Louviers, CO, Substantial damage. On November 27, 2017 at approximately 1520 local time, a Zenith CH750 cruzer received substantial damage to the right wing strut when it hit a barb wire fence… ## Docket (3 files) The files NTSB released with the investigation on March 8, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96397. 2.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40460717&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation (item 2, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40460718&FileExtension=.PDF&FileName=Record%20of%20Conversation-Master.PDF - Report Photos (item 3, .PDF, 4 photos, 223 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40460719&FileExtension=.PDF&FileName=Report%20Photos-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.