# NTSB WPR18LA102: Macdonald Craig MAC CUB, N669WH, Ogden, UT, March 5, 2018

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: March 5, 2018, 14:30 local (21:30 UTC)
- Place: Ogden, UT · muddy dirt road - off airport landing
- Coordinates: 41.121387, -112.08833 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.1214&lon=-112.0883&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Western Pacific Region
- Parties: Federal Aviation Administration
- SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs)
- NTSB case key (mKey): 96843
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR18LA102
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96843/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96843
- Page: https://openairdocs.org/ntsb/WPR18LA102

## Probable cause

The pilot’s failure to use carburetor heat during the flight, which resulted in a partial loss of engine power due to carburetor icing.

## 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: [Macdonald Craig MAC CUB, 1 case](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=05621DA), [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md)
- [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause); cases with it: [Macdonald Craig MAC CUB, 1 case](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=05621DA), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md)
- [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Incorrect use/operation (probable cause); cases with it: [Macdonald Craig MAC CUB, 1 case](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=05621DA), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Macdonald Craig MAC CUB, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05621DA), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md)
- [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Macdonald Craig MAC CUB, 1 case](https://openairdocs.org/ntsb-events/096/sequence.md?model=05621DA), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md)

## Analysis

The pilot and pilot rated passenger were conducting a local flight when the engine began to run roughly, and partial loss of engine power followed. The airplane was unable to maintain altitude, and the pilot made a forced landing onto a muddy road. During the landing roll, the airplane sunk in the mud, nosed over, and came to rest inverted, causing substantial damage to the left wing and vertical stabilizer. An engine examination and test run were performed, which revealed no preaccident mechanical failures or malfunctions that would have precluded normal operation. The nearest weather reporting facility, located about 6 nautical miles from the accident site, reported a temperature of 35.6oF and a dew point of 19.4oF, which was in the range of atmosphere conditions that are conducive to carburetor icing at glide and cruise power settings. The pilot reported that the carburetor heat was not activated at the time of the partial loss of engine power. The pilot also reported that he was in the rear airplane seat. Although the pilot had access to both sets of flight controls, the rear seat compartment was not equipped with a carburetor heat control handle. Engine power would likely have been restored if the carburetor heat had been engaged.

## Factual narrative

On March 5, 2018, about 1430 mountain standard time, an experimental MacDonald Craig Mac Cub airplane, N669WH, was involved in an accident near Ogden, Utah. The pilot and pilot-rated passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, while the airplane was maneuvering over a marshland, the engine began to run roughly, and a partial loss of power followed. Because the airplane was unable to maintain altitude, the pilot initiated a forced landing onto a 10-ft-wide muddy road. During the landing roll, the airplane sunk in the mud, nosed over, and came to rest inverted. The left wing and vertical stabilizer were substantially damaged. The pilot reported that the carburetor heat control was not activated at the time of the partial loss of engine power. The pilot was in the rear airplane seat, and the pilot-rated passenger was in the front seat. Although the pilot had access to both sets of flight controls, the rear seat compartment was not equipped with a carburetor heat control handle. The Ogden-Hinckley Airport (OGD) automated weather observing station was located about 6 nautical miles northwest of the accident site The 1353 observation reported that the temperature was 35.6°F and that the dew point was 19.4oF. An engine examination and test run were performed. The results revealed no preaccident mechanical failures or malfunctions that would have precluded normal operation. The Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention, stated the following: Pilots should be aware that carburetor icing doesn't just occur in freezing conditions, it can occur at temperatures well above freezing temperatures when there is visible moisture or high humidity. Icing can occur in the carburetor at temperatures above freezing because vaporization of fuel, combined with the expansion of air as it flows through the carburetor, (Venturi Effect) causes sudden cooling, sometimes by a significant amount within a fraction of a second. Carburetor ice can be detected by a drop in rpm in fixed pitch propeller airplanes and a drop in manifold pressure in constant speed propeller airplanes. In both types, usually there will be a roughness in engine operation. The special airworthiness information bulletin included a chart that showed the probability of carburetor icing for various temperature and relative humidity conditions. According to that chart, the weather conditions at the time of the accident were conducive to carburetor icing at glide and cruise power.

## Aircraft

- Registration: [N669WH](https://openairdocs.org/aircraft/N669WH), registered now, S/N 001 (OpenAirDocs)
- Reported make and model: MACDONALD CRAIG MAC CUB (NO SERIES)
- Registry model: [Macdonald Craig MAC CUB](https://openairdocs.org/model/macdonald-craig-mac-cub) (registry code 05621DA) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 001
- Year built: 2005
- Airframe hours: 290
- Engines: Lycoming O-360-A4G 195 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Condition, October 6, 2017, 100 hours before
- Destination: Same as departure
- Airport: BTF, Skypark
- Equipment: Handheld GPS

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; injuries: none; commercial, flight instructor, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review April 15, 2016; seat: rear; restraint: 4-point; flight hours: 3,200 total, 16 in this make and model, 2,611 as pilot in command, 30 in the last 90 days, 12 in the last 30 days
- Pilot-rated passenger; injuries: none; private; airplane ratings: single-engine land; medical: class 3; seat: front; restraint: 4-point

## Weather

- Conditions: Visual (VMC), Day
- Wind: 300° at 8 knots
- Visibility: 10 statute miles
- Lowest ceiling: 4,100 ft broken
- Temperature: 36 °F, dew point 19 °F
- Altimeter: 30.30 inHg
- Observed at: OGD, 6 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 20180305001469A](https://openairdocs.org/incident/20180305001469A), Mar 5, 2018: Macdonald Craig MAC CUB, West Point, UT, Substantial damage. On 5 March 2018, pilot and passenger decided to practice landings for about 30 minutes around btf. They decided to go sightseeing. About 20 miles north of…

## Docket (7 files)

The files NTSB released with the investigation on February 24, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96843. 5.6 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13130644&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf
- Record of conversation (lee) (item 2, PDF, 1 page, 107 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13221656&FileExtension=pdf&FileName=RoC%20CLee_Redacted-Rel.pdf
- NTSB examination report (item 3, PDF, 6 pages, 925 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13192986&FileExtension=pdf&FileName=Examination%20Report-Rel.pdf
- Report from FAA (item 4, PDF, 1 page, 29 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13128611&FileExtension=pdf&FileName=FAA%20Report%20N669WH%20accident_Redacted-Rel.pdf
- FAA SAIB CE-09-35 carburetor icing prevention (item 5, PDF, 3 pages, 106 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13220848&FileExtension=pdf&FileName=r_CE-09-35-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 6, PDF, 1 page, 371 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13130393&FileExtension=pdf&FileName=ntsbrelease_Redacted-Rel.pdf
- Photos - pilot (item 7, PDF, 2 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13192521&FileExtension=pdf&FileName=Photos-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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