Fuel totalizer vs tank gages

I'm cleaning up a 1991 rv4 fixed pitch w io320 that's been sitting, builder elected to install a totalizer but no fuel quantity gages. Not sure I like this set up, I would still like to have gages....any thoughts....do others have this set up?

Thanks. Tom

Personally, I want the gauges too.

Dave

Well, I would want gauges as well, even though they may not be the best. My RV-6 gauges are not very accurate.

Then there's this in your ops limits:
?After completion of phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with ? 91.205, this aircraft is to be operated under VFR, day only.?


And this:
FAR 91.205 (b) (9) Fuel gauge indicating the quantity of fuel in each tank.

I have VAN's fuel gauges. They aren't very accurate. The right gauge always reads lower than the quantity in the tank, so I guess it's 'safe'. The left gauge, reads higher than the quantity in the tank. Go Figure.
So I'm wanting to add a fuel computer, or maybe the MGL extreme EFIS with engine monitor as a cost effective way to upgrade several functions at once, but still leave panel space for a big screen later.

I should mention that I didn't build my 1993 vintage RV-6, and it has a Cessna gauge package in it that includes the fuel gauges. They accurately indicate both full and empty, it's that in-between part that is anyone's guess...

I added a Flight Data Systems FC-10 fuel computer and it's one of the best improvements I've made to the airplane.

http://www.fdatasystems.com/fc-10/

... I have both in my RV-9, the Flight Data Systems FC-10 computer is spot on, the Vans gauges are poor at best and never read correctly. I go by the computer and once stated that we should have left out the cheap Vans gauges. Everyone I stated this to immediately said " But what if you have an electrical problem?" "or must shut down the master?" Cheap gauges are electric as well and at this point neither will function. I have replaced these cheapo gauges two times and don't even look at them. The only problem with the fuel computer is if you need to turn off the power in flight for a given time the computer will lose its calculations and not track the fuel used while power is removed. Thanks, Allan...

Turbofan said:

I'm cleaning up a 1991 rv4 fixed pitch w io320 that's been sitting, builder elected to install a totalizer but no fuel quantity gages. Not sure I like this set up, I would still like to have gages....any thoughts....do others have this set up?

Thanks. Tom

Click to expand...

DougJ said:

Well, I would want gauges as well, even though they may not be the best. My RV-6 gauges are not very accurate.

Then there's this in your ops limits:
“After completion of phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with § 91.205, this aircraft is to be operated under VFR, day only.”


And this:
FAR 91.205 (b) (9) Fuel gauge indicating the quantity of fuel in each tank.

Click to expand...

Yep, the FARs state that fuel gauges are not required for day VFR flight. But I really like the EI dual gauge in my RV-6 for the past 16 years. It is very accurate at all ranges with the standard Vans float senders (except the top three gallons when the floats are against the top of the tanks).

http://www.aircraftspruce.com/catalog/inpages/eifl2m.php?clickkey=3629

After reading all the above posts, it sounds to me like it the gauges that are often inaccurate, not the senders? Is this correct? I believe the senders I got from from Vans are made by Stewart. Can I assume that my Stewart senders, connected to the EFIS will function reliably?

Bevan

My 2 cents...

With only a fuel flow totalizer installed, you might not detect a fuel leak on the low pressure side of the fuel system until the tank runs dry.

Tom is right

You want and need both indications. The fuel flow/totalizer is very accurate once it is calibrated and will give you all kinds of detailed information such as fuel needed to destination, remaining, etc. But if you have a leak in the tanks (yes, a fuel drain can stick open without being noticed) or forget to input the fuel-added to the totalizer, it can soon become very inaccurate and misleading.

Vic

human error

If you don't fill the tanks to the top, or even forget one entirely, then re- set the totalizer, it will of course be wrong.

In my experience (GRT) if the EFIS or EIS lets you calibrate the float gauges, they are quite accurate. Except, as noted, the top few gallons when the float is pinned to the top.

Bevan said:

After reading all the above posts, it sounds to me like it the gauges that are often inaccurate, not the senders? Is this correct? I believe the senders I got from from Vans are made by Stewart. Can I assume that my Stewart senders, connected to the EFIS will function reliably?

Bevan

Click to expand...

Depends on the equipment in the tank to measure the fuel and the indicator in the cockpit.

The float type senders will rarely be accurate throughout the range of the tank because the float is attached to the inboard rib. Consequently, it only measures the fuel quantity in the inboard bay. The float will measure "full" on a tank that is truly full all the way down until enough fuel has been consumed to cause the fuel level to decrease in the inboard bay. It can be set up so that it indicates empty when it truly is empty.

I have a now dated VM1000C capacitance probe system and associated fuel computer/totalizer. The proble is installed across the rear baffle of the tank from the highest point at the outboard rib to the lowest point on the inboard rib. The gages read in 1 gallon increments. The actual fuel quantity in my tanks is always within +/- 1 gallon of what the gages indicate. In theory, it is possible for my total fuel quantity indicated on the gages to be off by as much as 2 gallons, but it is always within a gallon of what the totalizer indicates. The totalizer itself is within 0.5 gallons of the actual fuel quantity in the tanks 98% of the time. In a nutshell, when I show up to the pump, I'm always within a gallon of what I think it should take.

This probe would be impossible to retrofit to an existing tank without major surgery, but there are other capacitance systems I'm not that familiar with. Maybe some others can chime in.

Jerry Esquenazi
RV-8 N84JE

Don't discount the float senders, I've found them to be accurate throughout the range once three or four gallons have been burned from a topped tank. The key is to calibrate the electronic gauge (or EMS) from the bottom up. Begin with an empty tank and continue the calibration until full.

The EI gauge I use with the floats is very close to what the totalizer calculates as long as I am careful with inputting data into the fuel computer (Trio Pro Pilot).

ditto this

Sam Buchanan said:

Don't discount the float senders, I've found them to be accurate throughout the range once three or four gallons have been burned from a topped tank. The key is to calibrate the electronic gauge (or EMS) from the bottom up. Begin with an empty tank and continue the calibration until full.

The EI gauge I use with the floats is very close to what the totalizer calculates as long as I am careful with inputting data into the fuel computer (Trio Pro Pilot).

Click to expand...

you need gauges in case of fuel tank leak. EI are accurate once you burn off about 4 gallons. I calibrated mine to be be the most accurate for the lower half of the tank. it has been very good.