Sunday, March 18, 2018

Zenith CH 750 Cruzer, N956GM: Accident occurred November 27, 2017 in Louviers, Douglas County, Colorado

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Denver, Colorado

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Louviers, CO
Accident Number: CEN18LA042
Date & Time: 11/27/2017, 1520 MST
Registration: N956GM
Aircraft Damage: Substantial
Defining Event: Loss of engine power (total)
Injuries: 1 None
Flight Conducted Under:  Part 91: General Aviation - Flight Test 

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."

Pilot Information

Certificate: Commercial
Age: 61, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land; Single-engine Sea
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used: 3-point
Instrument Rating(s): Airplane
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: BasicMed Without Waivers/Limitations
Last FAA Medical Exam: 05/04/2017
Occupational Pilot: No
Last Flight Review or Equivalent: 05/13/2017
Flight Time:  3100 hours (Total, all aircraft), 32 hours (Total, this make and model), 3100 hours (Pilot In Command, all aircraft), 39 hours (Last 90 days, all aircraft), 10 hours (Last 30 days, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Manufacturer: MOTLEY GARY W
Registration: N956GM
Aircraft Category: Airplane
Year of Manufacture: 2017
Amateur Built: Yes
Airworthiness Certificate: Experimental
Serial Number: C75-10359
Landing Gear Type: Tricycle
Seats: 2
Date/Type of Last Inspection: 09/17/2017, Condition
Certified Max Gross Wt.: 1645 lbs
Time Since Last Inspection: 32 Hours
Engines: 1 Reciprocating
Airframe Total Time: 32 Hours as of last inspection
Engine Manufacturer: VIKING
ELT:  Installed, not activated
Engine Model/Series: 130GDI
Registered Owner: On file
Rated Power: 130 hp
Operator: On file
Operating Certificate(s) Held:  None 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: APA, 5883 ft msl
Observation Time: 1453 MST
Distance from Accident Site: 9 Nautical Miles
Direction from Accident Site: 40°
Lowest Cloud Condition: Few / 11000 ft agl
Temperature/Dew Point: 25°C / -12°C
Lowest Ceiling: Broken / 22000 ft agl
Visibility:  10 Miles
Wind Speed/Gusts, Direction: 16 knots/ 27 knots, 220°
Visibility (RVR):
Altimeter Setting:  29.66 inches Hg
Visibility (RVV):
Precipitation and Obscuration:
Departure Point: BROOMFIELD, CO (BJC)
Type of Flight Plan Filed:  None  
Destination: BROOMFIELD, CO (BJC)
Type of Clearance: VFR
Departure Time: 1440 MST
Type of Airspace: Class E 

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude:  39.462222, -105.007778 (est)

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