# NTSB CEN22LA093: Zenith CH750, N750DP, Montrose, CO, January 2, 2022

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: January 2, 2022, 10:40 local (17:40 UTC)
- Place: Montrose, CO · Mountain plateau 20 S of Montrose
- Coordinates: 38.44, -108.28 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.4400&lon=-108.2800&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute: Unknown or undetermined](https://openairdocs.org/ntsb-events/000)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Central Region
- Parties: FAA
- NTSB case key (mKey): 104489
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN22LA093
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/104489/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=104489
- Page: https://openairdocs.org/ntsb/CEN22LA093

## Probable cause

A partial loss of engine power for reasons that could not be determined based on the available evidence.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Aircraft](https://openairdocs.org/ntsb-findings/01050000): Aircraft › Aircraft power plant · Unknown/Not determined (probable cause); cases with it: [Piermattei Donald L ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-findings/01050000/cases.md?model=05629UN), [All aircraft, 151 cases](https://openairdocs.org/ntsb-findings/01050000/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 (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Piermattei Donald L ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05629UN), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md)
- [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Piermattei Donald L ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05629UN), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)
- [Enroute: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) (defining event); cases with it: [Piermattei Donald L ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/000/sequence.md?model=05629UN), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md)

## Analysis

The pilot stated that, about 30 minutes after departure and while in cruise flight at an altitude of about 10,500 ft mean sea level, he observed the fuel pressure decrease from 44 to 39 pounds per square inch (psi), increase to 40 psi, and decreased to 0 psi as the engine speed decreased to 0 rpm. For about the next 3 to 5 minutes, the fuel pressure and RPMs fluctuated between normal and zero. He activated the backup fuel pump with no effect noted. The airplane sustained substantial damage to both wings during the forced landing. A postaccident examination revealed no mechanical malfunctions or anomalies that would have precluded normal operation. Engine runs were performed with no anomalies noted that were consistent with the pilot’s statements and onboard recorded data. The onboard recorded data showed fluctuations in fuel pressure and intermittent operation of the engine consistent with the pilot’s statement. As a result, the reason for the partial loss of engine power could not be determined based on the available evidence for this investigation.

## Factual narrative

On January 2, 2022, about 1040 mountain standard time, a Zenith CH750, N750DP, was substantially damaged when it was involved in an accident near Montrose, Colorado. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that, before taking off, he added 23 gallons of 92 octane, ethanol free automotive gas to the fuel tanks. After the fuel settled, he checked the sump in the fuel tanks and observed no contamination or water in the fuel. About 30 minutes after departure and while in cruise flight at an altitude of about 10,500 ft mean sea level, the pilot observed the fuel pressure decrease from 44 to 39 pounds per square inch (psi). The fuel pressure then increased to 40 psi before decreasing to 0 psi as the engine speed decreased to 0 rpm. For about the next 3 to 5 minutes, the fuel pressure and engine speed fluctuated between a normal psi and rpm, respectively, and zero. The pilot activated the backup fuel pump with no effect noted. The pilot decided to execute a forced landing on top of a snow-covered plateau about 20 miles south of Montrose. During the landing, the nosewheel dug into the snow, causing the airplane to flip over, which resulted in substantial damage to both wings. During a postaccident examination, fuel was supplied to the airplane’s engine, which started without hesitation. After the engine warmed up, the throttle was increased, and the engine continued to run at almost full power. When the backup engine control unit was activated, the engine coughed and then quit. After the unit was turned off, the engine restarted, but the engine quit when the unit was turned back on again. The airplane was installed with a Dynon Skyview electronic device. The data retrieved from the device showed that, between about 1035 and 1037, the fuel flow rate decreased from 5.9 to about 5.0 gallons per hour with no other changes noted. About 1037, the engine rpm and fuel pressure both decreased to zero, returned to their original value, and then decreased back to zero. These fluctuations continued until the data ended about 1040:30. During this same timeframe, the fuel flow rate steadily decreased, the oil pressure fluctuated between about 60 and 75 psi, and the amperage fluctuated between about 5.7 and 9.5 amperes.

## Aircraft

- Registration: [N750DP](https://openairdocs.org/aircraft/N750DP), registered now, S/N 7588, built 2010 (OpenAirDocs)
- Reported make and model: ZENITH CH750
- Registry model: [Piermattei Donald L ZENITH CH 750](https://openairdocs.org/model/piermattei-donald-l-zenith-ch-750) (registry code 05629UN) (OpenAirDocs)
- Registry engine: [Honda VIKING](https://openairdocs.org/engine/honda-viking) (registry code 33803, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 7588
- Year built: 2010
- Airframe hours: 109
- Engines: Viking Aircraft 110 110 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Special, Experimental light sport (Special)
- Last inspection: Annual, January 7, 2021, 21.4 hours before
- Departed: 7V2, Poania, CO
- Destination: KBDG, Blanding, UT
- Airport: n/a
- Equipment: Electronic multifunction display, Electronic flight bag or handheld device, Onboard weather, ADS-B, Angle of attack indicator, Data recorder

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 63; injuries: none; sport pilot; medical: sport pilot; last flight review December 14, 2021; seat: left; restraint: 5-point; flight hours: 161 total, 98 in this make and model, 94 as pilot in command, 8.7 in the last 90 days, 8.7 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 160° at 6 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 9 °F, dew point -0 °F
- Altimeter: 30.49 inHg
- Observed at: KMTJ, 18 nm away
- METAR: KMTJ 021653Z AUTO 16006KT 10SM CLR M13/M18 A3049 RMK AO2 SLP406 T11331178

## 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 20220102000199A](https://openairdocs.org/incident/20220102000199A), Jan 2, 2022: Piermattei Donald L ZENITH CH 750, Montrose, CO, Substantial damage. While the aircraft was in cruise flight the pilot reported that the engine began to lose and then regained power repeatedly. The pilot attempted to adjust…

## Docket (7 files)

The files NTSB released with the investigation on June 14, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=104489. 18.0 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 4.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14090475&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf
- Engine examination mfr (item 2, PDF, 2 pages, 155 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14109588&FileExtension=pdf&FileName=Engine%20Examination%20MFR-Rel.pdf
- Cockpit display - specialist's factual report_CEN22LA093 (item 3, PDF, 15 pages, 4.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14011772&FileExtension=pdf&FileName=Cockpit%20Display%20-%20Specialist%27s%20Factual%20Report_CEN22LA093-Rel.pdf
- Attachment 1 to cockpit display - specialist's factual report_CEN22LA093 - tabular data (item 4, CSV, 7.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14011543&FileExtension=csv&FileName=Attachment%201%20to%20Cockpit%20Display%20-%20Specialist%27s%20Factual%20Report_CEN22LA093%20-%20Tabular%20Data-Rel.csv
- Attachment 2 to cockpit display - specialist's factual report_CEN22LA093 - alert data (item 5, CSV, 62 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14011925&FileExtension=csv&FileName=Attachment%202%20to%20Cockpit%20Display%20-%20Specialist%27s%20Factual%20Report_CEN22LA093%20-%20Alert%20Data-Rel.csv
- Photos (item 6, PDF, 3 pages, 572 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14096065&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 7, PDF, 1 page, 565 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14097498&FileExtension=pdf&FileName=Signed%20Wreckage%20Release_Redacted-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.

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