Annunciator Panel vs Fuel Gauges

[AlanA]

Like many older Mooneys, the fuel gauges in my J are not very accurate.  My question is, are the fuel low annunciator lights still accurate even if the fuel gauges are not?    

 

Question #2 :  I have a EI fuel flow,  Would there be any integration problems if I installed the Aerospace Logic fuel gauges also?

[Bob - S50]

We installed the Aerospace Logic fuel gauge in our J. According to our A&P the instructions say to disconnect all other fuel indicators from the system so our stock gauges and annunciator indications are inop. Our gauge is accurate in smooth air in level flight but indicates high on the ground due to nose attitude and indicates low during descent. Only off by a couple gallons though. We set our "red" indication at 2.5 gallons for each tank and set the "yellow" level at 5 gallons. Obviously, in turbulence the floats bounce around and the fuel indications vary accordingly.

Bob

[AndyFromCB]

What are fuel gauges and who uses them? You have EI fuel flow totalizer, why even bother looking at anything else. Put it 64 gallons, burn 54, land, rinse, repeat.

[sreid]

What are fuel gauges and who uses them? You have EI fuel flow totalizer, why even bother looking at anything else. Put it 64 gallons, burn 54, land, rinse, repeat.

Edward Snowden

[Roger O]

Not to be a contrarian, but when I learned to fly many moons ago, my CFII told me to NEVER trust a fuel totalizer alone.  Yes they work at telling you what your engine burned and by definition what you have left, but does not tell you how much fuel you are jettisoning due to that lose fuel cap or punctured fuel line.

 

Use the fuel totalizer for accurate readings in a well sealed functioning system, but always check your fuel gauges as the definitive backup that all is working as advertised, and you are not losing fuel..

[Bob - S50]

Not to be a contrarian, but when I learned to fly many moons ago, my CFII told me to NEVER trust a fuel totalizer alone.  Yes they work at telling you what your engine burned and by definition what you have left, but does not tell you how much fuel you are jettisoning due to that lose fuel cap or punctured fuel line.

 

Use the fuel totalizer for accurate readings in a well sealed functioning system, but always check your fuel gauges as the definitive backup that all is working as advertised, and you are not losing fuel..

I concur.

Bob

[AlanA]

I love having the fuel flow computer but it doesn't show what is in each tank, only the total fuel on board.  On a long flight I keep track by switching tanks every 5 gallons, however when I come back to the plane a few days later, or after a few small flights I don't always remember which tank I started with.  I would just like to know how much is in each tank.  

 

And this is why I have the question about the annunciator panel verses the fuel gauges.  If the annunciator panel is still accurate even when the fuel gauges are not then I probably won't bother installing new gauges.  At least I would know that when I am down to 2.5 - 3.0 gallons in the tank.  However, if the annunciator panel  is inaccurate as well, then I may decide to install the Aerospace logic gauge.  

[scottfromiowa]

Run it down and ground run it to see if it works. The reason I swap tanks every hour is so I don't forget which tank I started wth. I would get confused if I did every 5 gallons too. I plan on a burn of 10GPH. If less fuel flow/totalizer will tell me, but I have MORE not less than I planned on. My gauges are reading better than ever, but have always been accurate on six and below.

[carusoam]

I think you have it covered when you have...

Two independent electronic gauges...

Two independent mechanical gauges...

Two low level warning lights... As accurate as you test them to be...

Fuel flow...

Fuel totalizer...(reset in you procedure)

You visually checked both tanks at the top...

You visually checked both drains at the bottom...

You have a fuel procedure...

You follow the procedure...

You have a preferred supplier of seals for both the inner and outer seals of the fuel cap...

You have a spare drain in your tool box.

You always add more fuel unless weight or other limiting factor is driving the decision...

My procedure adds the next pieces.

Start on the left.

Top of climb switch to the right.

Every hour. Switch tanks.

Adjust rudder trim to center the ball.

If I get confused or forget what I did, going back to the procedure will help.

I use the flight timer on the IP to judge when the next step should be accomplished.

Let me know if I missed something. Fear of running out of fuel drives this logic.

Best regards,

-a-

[ArtVandelay]

Like OP, my gauges are not accurate, couple of follow up ?s:

Because fuel gauges must be accurate (at least at empty), are these checked at annual?

Are these consider an airworthiness issue?

I've got the gang of six, I assume to replace this is expensive?

Why are these a problem with mooneys, is it a instrument problem or sensor problem?

[carusoam]

They're just age dependent i'm sue it isn't Mooney specific...

Best regards,

-a-

[1964-M20E]

When the big fan up front stops turning and all goes quiet switch tanks and restart the fan.  Just make sure it's not on in the pattern.

 

Well I have the EI FP5 in my plane and the original Mooney gauges.  I look at the gauges occasionally and use the fuel flow to bur specific amounts from each tank.  I have bladders so only 54 gallons available. If I'm on a long flight where I suspect I'll be down to my reserve by time I land I will run one tank completely dry that way everything else is in the remaining tank.

 

 

As said above I have a procedure and use it.