Fuel flow gauge question.

[Lood]

My F sports the MP/fuel flow combination gauge and ever since I bought it, back in 2008, the fuel flow gauge was off. When the engine is shut down, the indicator needle on the fuel flow is not indicating right on "0", but rather "-2" gal/hr. Sadly this fault is also present during flight - the gauge thus always indicates about 2 gal/hr short of the actual consumption.

Not a train smash, as I do have a JPI with FF, but I get extremely annoyed by things not working as they should.

 

My question is: can the fuel flow gauge be opened by a qualified person, and the indicator needle be moved and reinstalled in the correct position? I've never seen the inside of this gauge, so I'm not sure whether the needle could just be pulled and adjusted or moved to the correct position?

Apart form this, the gauge does function properly and as it should. I would appreciate advice from anyone who might have knowledge of the inner working of a fuel flow gauge.

[Marauder]

Are you talking about this gauge? Mine shows fuel pressure. I didn't know they made a fuel flow gauge. If it is this gauge, fuel actually comes up to this gauge. If it was only off when shut down It might be due to an obstruction that doesn't let all of the pressure out and the needle to rest. Most of these gauges can be serviced.

[N201MKTurbo]

Most instrument shops should be able to repair or overhaul that gage for a few hundred bucks.

If you can get the model number of the gage, you can call the shops to see if they have the capability to work on it.

The fuel flow gage measures the pressure at the sense port on the flow divider.

I've never seen one in a mooney, they usually have a fuel pressure gage.

[Marauder]

The fuel flow gage measures the pressure at the sense port on the flow divider.

I've never seen one in a mooney, they usually have a fuel pressure gage.

I would be curious to see the gauge he has. I have been in a number of Mooneys and I can't ever recall seeing a fuel flow gauge.

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[scottfromiowa]

My bet is that Op'er meant fuel pressure...

[mooniac15u]

http://mooneyspace.com/topic/11929-wanted-direct-replacement-aerosonic-mapff-instrument-for-1979-m20k-231/

[Marauder]

http://mooneyspace.com/topic/11929-wanted-direct-replacement-aerosonic-mapff-instrument-for-1979-m20k-231/

There is such a critter!

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[carusoam]

Expect that it is an FP gauge calibrated in GPH.

Constant fluid parameters in combination with constant flow geometry allows a pressure transducer to be used as a flow meter.

Unfortunately something like a deposit in the tube can lead to an erroneous reading, making calibration challenging.

Best regards,

-a-

[Lood]

Thanks to all for the replies. I would like to emphasize that the gauge is working perfectly well, apart from the indicator needle needing a bit of repositioning. It basically indicates low with the same distance that the needle shows on the picture. IAW, if the needle was set to indicate right on "0" with the engine shut down, it should also give the correct reading with the engine running.

I'm not sure whether this gauge was installed afterwards, I bought the plane with it in the panel and I'm rather confident that it is indeed a FF gauge and not FP. I've attached a cell phone pic, so pardon the poor quality.

[Guest]

It looks to me like a gauge more common to a Piper Arrow, not a Mooney.

Clarence

[carusoam]

I like the % power references...?

Starting the conversation of LOP/ROP.

Best regards,

-a-

[Ned Gravel]

It looks to me like a gauge more common to a Piper Arrow, not a Mooney.

Clarence

I remember that one from my old Piper Arrow. Sometimes wish I had one in the Mooney - but dependable.

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[harrispa]

I could be wrong, but that sure looks like a fuel pressure gauge calibrated to fuel flow

[N201MKTurbo]

I could be wrong, but that sure looks like a fuel pressure gauge calibrated to fuel flow

 

That is what a fuel flow gauge is....

 

It is a pressure gauge connected to the flow sense port on the flow divider. Calibrated for flow.

[Lood]

Thanks guys. However, I just learned that my brand new EDM 900 will fulfill both these functions, so I'll not bother to get this fuel flows' needle fixed.