Fuel flow zero

Anyone else have fuel flow reading go to zero while the engine is running? That symptom typically coincides with %Power also reading zero–especially during flight. It is most likely the fuel flow sensor either failing to spin in order to read the rate of fuel flow, or the boost pump going out, or maybe the fuel flow sensor connector.

If so, know that this problem renders your plane NOT airworthy because the POH KOEL (kind of operation equipment list) shows that a fuel flow indication is necessary in all kinds of operation (VFR, IFR, Day, Night)!

I have a 2020 SR22T and I understand these sensors have been doing this. Anyone else going through this issue out there?

Of the possibilities you mentioned, the least likely is the fuel pump failing as that would lead to a very unhealthy running engine. Most likely the fuel flow sensor or connector. The percent power goes out because that reading is based on a genuine fuel flow reading to calculate the value.

I agree with you!

I have had this issue and it was the connection. Turns out it was also the cheapest to fix so always a great place to start.

Thanks I will check that out. But I did get the fuel flow to show again by turning on the high boost pump so I think the sensor was stuck.

Had this exact issue last month in IMC on departure- both power and FF went to zero. Engine kept turning and we flew it back around to our departure airport.

Turned out to be a bad fuel flow sensor that decided to call it a day at 1000 feet AGL in the clouds. Those first 5 seconds of processing if my instruments are lying or if I’m 5 seconds from a cape pull were very long. Had a fantastic friend/pilot right seat and it was great to have a second brain troubleshoot with you.

Yes it is very alarming to look down and see 0 fuel flow and 0 %power!

Also of course if it happens on a flight then the totalizer and all calculated fuel remaining numbers should not be relied upon. Only the fuel gauges can be used.

I had the exact same issue in a 2019 SR22T just a few weeks ago. Replaced FF sensor and problem was resolved. It is a bit more tricky to fly without the % Power and fuel flow but thankfully you can watch the Temps and manifold pressure to smoothly get back to an airport.

Just had my sensor replaced today. It’s buried under the intake manifold just above the cylinder heads. Took 2 hours.

This is why learning the power setting purely by looki ng at percent power is a bad idea. It helps to know the corresponding MP and RPM settings in case this happens. At the time of the failure you hopefully already had the correct fuel flow so losing the FF gauge is not a big deal in that setting. Fuel sensor issues and connector problems continue to pop up even in the new planes with the “better wiring and connectors”. having a plan to deal with it ahead of time prevents the “deer in the headlights” mental state when it happens.

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Yes, after the fuel flow sensor has failed in flight, especially when needing to land, that learned reliance on % power can leave the PIC in a real lurch when the MFD suddenly reads “0% power.” So if that happens remember: watch AIRSPEED with extra special care!

I had 0 RPM after a P-static event flying up in Alaska.

There was a big twirling RPM gauge on the front of the airplane that I felt was more accurate at that point.

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I’m probably gonna have to order a sensor in the next week. Price still $2100 or so?

I also had the same issue in my 2020 SR22T … checked connectors first, but ended up needing a new fuel flow transducer.

This is crazy. I just had the exact same issue flying a 2019 22T last week. The first shop wiggled some connectors and the issue cleared itself up. But after a few days it has returned and disappeared once again. The shop up near KCOQ said the fuel flow sender was fine but I’m curious if this is something that can be tested or if they are trying to avoid replacing it.

The transducer can indeed fail intermittently. Beware: since the POH shows “fuel flow indication” in the KOEL list of necessary equipment under all kinds of operations (VFR, IFR, day, night), the plane is NOT AIRWORTHY without an operative fuel flow transducer. Worse yet, the AOPA legal department attorney told me that in such cases the FAA considers even intermittent failures as an “inoperative” condition. And if the FAA finds that you took off when you knew or should have known that the transducer was “inoperative” they may see that as a willful violation (and they can and do regularly monitor these blogs). And they know when you fly from your ADS. Of course, if it fails while you are airborne, my understanding is that you may fly to where it can be replaced (the unit is not designed to be serviced). Choose where to land wisely since once on the ground you are stuck there until securing a Ferry Permit which can sometimes take days and even an FAA inspector to come see the plane beforehand.

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Perhaps use stabilant 22 on the baffle connector pins of the fuel flow sensor. Red arrow points to the connector.

Seriously? Has this happened to you? Or someone you know?

If you read through the million posts here on copa for the past 18 years (as I have), there have been many posts about inoperative avionics, trim motors, stall horns, engines sensors (CHT, EGT, Oil pressure, Oil temperature, Outside air temperature). And a lot more.

Yet there has not been one report of what you claim.

I’ve often wondered why a fuel flow indication is required since many planes don’t even have one. The only thing I can think of is that there have been some issues with excessive fuel flow on take off and they consider it an excessive risk if the system is unable to warn you about it with a CAS message.