High Fuel Pressure Warning

[csalewski]

This evening at the end of a local flight (KLZU to Georgia Mountains) during descent at about 3200ft I had several high fuel pressure warnings.
Fuel pressure went from about 26psi up to 38psi (max. range on scale) for 5 to 10 seconds then back to normal. This happened 3 times in about 2 minutes. Electric fuel pump was off. I only reduced MP slightly from 21 to 19 at the second warning since engine was running smooth.
Fuel flow (checked in G1000 flight log) was constant at 8.9gph even during the spikes.

I kept it level at 3,000 ft (2000 agl about 5 miles from KLZU), turned electric fuel pump on, mixture to full rich. Fuel pressure remained in the green for the remaining 6 minutes of flight time. I let tower know that I come in high because of unknown cause for an intermittent warning and the controller gave me priority without making this an emergency.

Has anyone seen a high fuel pressure warning? (Could not find a thread)
Is my assumption that the transducer goes bad a safe one?
Would a mech. fuel pump going bad produce high pressure?
Would anyone not cancel an 80NM trip next morning with this known issue?
__________________
Carsten
N159PS

[Rick]

Carsten, check the G1000 data file from the trip. Specifically, look at the "E1 FPres (psi)" data - column X in Excel. It would be interesting to see how quickly the value changed, and to what actual value, when you were having this problem. I would think if the value jumped a large amount very quickly, or went to some unreasonably high value, it's probably just a fuel pressure sensor (or wiring) problem. Also, I would look at the FPres value for the rest of the flight and see if it was relatively constant or if there were other problem spikes during the trip. This information might give you or your mechanic a better idea of where the problem lies, and how concerned you should be.

It's kind of funny to think back to all the years we flew without knowing or even thinking about the fuel pressure...

[csalewski]

Rick,

Yes I looked at it. The spikes happened pretty abruptly. See sample data at the end and graph for whole flight.



27.89
28
28.09
27.92
31.05
33.27
34.63
36.18
37.09
38.8
37.72
35.83
32.34
30.87
29.42
28.63
28.44
28.27
29.87
32.34
34.73
35.04
37.01
37.32
38.26
38.78
38.94
36.52
33.52
31.41
30.06
29.51

[smoss]

resurrected thread from the dead...
My last flight I had a similar occurrence, with fuel pressure spiking up to 86 (per my log file), giving the dreaded G1000 warning alert tone and flash, then gradually returning to normal (24 psi or so) over about 15 seconds. No change in engine running, and fuel flow stayed essentially the same. This was at a MAP of about 10, 2500 RPM. About 5 minutes later, it did the same thing again when I slightly adjusted the power, still at about the same settings, this time returning to normal over about 8 seconds. I was near my home airport, so climbed again and tried to reproduce it, but could not make it happen again. No change with or without electric pump. Did you ever figure out yours Carsten? Mechanic consensus was it's probably a sensor issue.

[csalewski]

resurrected thread from the dead...
(...) Did you ever figure out yours Carsten? Mechanic consensus was it's probably a sensor issue.

I could not reproduce it nor did it ever happen again. We cleaned the sensor contacts after the flight but did not go through swapping the fuel and oil pressure sensors or anything. The conclusion was since the fuel flow remained constant it was not a clogged fuel line or pump issue. But I remember the G1000 warning and flashing very well - not what you want to hear and see...
I think that it was rather easy to disconnect the pressure sensor contacts. Wish I had taken a picture. It all looked clean so maybe even the disconnect and reconnect solved the problem.

Carsten

[smoss]

I'll give it a try, thanks. If only our plane had access panels in the cowling like in the seats!

[Eric N]

I had a similar issue, but with the oil pressure. I was told the fuel and oil pressure sensors are identical, so we decided to try switching the senders (based on DAC's suggestion) and the problem went away, never to return. I would agree with the suggestion that this is a sender issue, not a "real" problem. We have for quite a while flown with a 2GB SD card in the upper slot of the MFD, and this "flight recorder" function provided lots of data to help trouble shoot this problem. I highly recommend it for G1000 fliers.

[carym]

We have for quite a while flown with a 2GB SD card in the upper slot of the MFD, and this "flight recorder" function provided lots of data to help trouble shoot this problem. I highly recommend it for G1000 fliers.

Eric,
This is another example of the lack of support by DAI for the "legacy" DA42's. Although I have the G1000 with the latest approved software, Diamond will not approve a change in software to record such data on the upper slot of the MFD. To get that I have to convert my plane to a NG version. While I agree that having that function is very valuable, I am just not sure it is worth spending $250,000 to get that function.

[Eric N]

Hi, Cary--I recall having lunch at ASH with you and Phil Cox a ways back. It certainly makes no sense for DAC to be so unsupportive in this (and other) aspect. I agree, though, that I wouldn't spend that amount for not much benefit. I think us DA40 types got it with .23 version of the system software, along with a revival of the checklist function.
Cheers.

[carym]

Hi, Cary--I recall having lunch at ASH with you and Phil Cox a ways back. It certainly makes no sense for DAC to be so unsupportive in this (and other) aspect. I agree, though, that I wouldn't spend that amount for not much benefit. I think us DA40 types got it with .23 version of the system software, along with a revival of the checklist function.
Cheers.

Boy, that was a way back. I haven't heard from Phil in a while, even though I have sent him a message (thru the other board). While I don't have the engine info recording function, at least I do have the checklist function. I should be thankful for small favors