This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
I experienced an engine failure in a Cessna 172.
The flight was a normal pattern work training flight that began with a routine flight to ZZZ1 followed by two laps in the pattern. In the downwind at ZZZ1 on the third lap I felt a small drop in RPM. I asked the student if they had pulled the throttle to which they answered yes.
Out of an abundance of caution I decided to return to ZZZ early because I wasn’t confident in his answer. We climbed to 3,000 feet with the mixture full rich. We experienced extreme oil pressure abnormalities and oil pressure in the red on the return. This turned out to be a sensor failure, according to maintenance.
Approximately five miles from ZZZ the fuel servo failed, causing flooding of the engine. Fuel flow got stuck around 9 gph regardless of throttle/RPM setting.
As we reduced power for descent, fuel flow remained the same and caused flooding of the engine. This led to engine roughness on downwind and extreme engine roughness on base to final. The aircraft also reached approximately 700 rpm while in flight and 600 rpm around the threshold.
On touchdown the engine failed completely, causing us to be unable to clear the runway without being towed. Maintenance found that this was due to a fuel servo failure causing the engine to be flooded with fuel and ultimately resulting in engine failure.
According to the director of maintenance if I had not increased power on final when I did the engine would have failed earlier. This is one of many fuel servo failures ZZZ has had over the last few months.
Primary Problem: Aircraft
ACN: 2185142
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Ever consider REMOVING THE MIXTURE FROM THE FIREWALL setting????????????
If the engine is flooding, LEAN THE d(&(^ THING
You’re fuel has fine grit in it that galls the slide in the fuel control valve in the servo. That causes the fuel control valve to stick open. Solution in the air is to run at full throttle until you reach your airport, as it will load up and die when you throttle back. Another reason why pilots should be practicing engine out landings. If you practice, you’ll hit the runway. If not, most come up short. Some will overshoot.
If you are having numerous failures, your fuel service needs to change their filters more often and maintenance needs to clean the inlet filter on the fuel servos when they do their 100 hr inspections. I would bet they aren’t servicing the servo filters.