Draining tanks and fuel quantity calibration.

[Igor_U]

With new fuel gages finally installed (Aerospace Logic FL202) next step is to drain tanks and calibrated them.

 

I’ve run one tank dry inflight (it be really impractical to do that with both) so there should be only unusable fuel there.

My idea was still to remove that wing tanks drain and empty remaining fuel to jerry can. Is that really necessary or I can assume fuel in that tank is at unusable level?

Should I just pull the sump drain in cabin and not to remove the drain in wing, if I need to drain last gallon?

 

Plan is then to level the plane, as per manual and add half of unusable fuel (for LH tank only) and continue with calibration.

Then fly the other tank dry…

 

What would others do?

Originally, I thought of draining fuel from tank to jerry cans but I wasn’t really comfortable with idea of fuel dripping down my sleeves and wing so flying full bore to burn it seemed more fun.

 

How do you level the plane? Manual says deflate/inflate tires as necessary (paraphrasing) but I see no such adjustment available just deflating the nose tire.

I am measuring with level a skin splice above battery access panel and angle is bigger (nose up) then flat nose while would allow.

Plus, I need to fly to nearby airport as KPAE has self-service pumps broken for over a year now.

 

I made a beveled 2x6” so I can roll MLG on it and get some nose down attitude and ramp at the pumps is also sloped so this should bring it close to “level”.

If it was my home field, I’d use jacks to level the plane but I don’t want to deal with fuel truck pouring 2 gal then wait for a minute or so.

What do you say?

 

 

How do you interpret note 1 from TC?

 

 

 

The way I read it (for M20F) is we have 64 gallons Tank capacity and additional 15lb (2.5 gal) unusable fuel. It says: not included in fuel capacity.

I seem to remember there are some differences between old certification standards (CAR3) and part 23 but it’s all foggy now.

 

 

Thank you.

 

 

[Guitarmaster]

Drain a majority of the fuel through the sump.
Level the plane and drain the rest through the strainer.
You now have all the useable fuel out. This is your zero reading.
Keeping the plane level (with jacks. If you run it up on ramps, the plane will settle with the weight of the fuel and your measusurements will be off) Fill 8, 16, 24, and 32 (don't top it off or your reading will be off). Let the fuel settle at each point.
Fill out the table and you are done.

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[carusoam]

Why one drain counts and the other drains don’t...

1) the left and right fuel sumps are lower than their respective fuel pick ups.  So they drain more than useable fuel...

2) the fuel separator is a great way to know if the fuel drained was going to be useable. If it gets to the separator it was coming in through the useable fuel line...

3) there is a few ounces of fuel that can be drained from the separator... that are in fact... not useable...  theses ounces of fuel are sitting below the exiting fuel line...

4) if your calculations are so accurate that it includes the volume of the fuel sep... it would help to get the internal dimensions of the the fuel sep....

5) leveling the wings side to side is probably the most important for volume changes.  There is a lot of empty room in the tanks above the fill hole.

6) leveling the plane nose to tail... makes more fuel available... the fuel pick up is placed near the back of the tank... so when climbing with little fuel left...nose high empty’s the tank more... you are more likely to run out of fuel when in a favorable, nose low, situation...

7) Leveling is important to measure useable fuel... available to the tanks... but... it’s important when filling the tanks to be near level as well.. you can put more fuel in a low wing....

8) use caution to not accidently be overweight, or under fueled...

9) The advantage of following the standard rules when determining the useable fuel.... Being in a standard flight, level, pulling 1g, running out of fuel will happen more predictably... being at the front of the envelope, running out of fuel will happen predictably sooner...

10) Trying to game the system may actually work very well... if you raise the nose to send the fuel back to the pick-up, will result in slower flight..  for maximum efficiency... Vz or Carson’s speed is your friend when you only have a gallon or two left on board...

11) for a better feeling about the location of the fuel pick-up... Find the pics posted in any tank stripping thread... Alex posted some good ones...

 

Continue to use extra caution when handling fuel, grounding everything before touching it... static sparks can be really bad...

 

PP thoughts only, not a mechanic...

Best regards,

-a-

[gsxrpilot]

Kudos on running a tank dry in flight. That is the ONLY way to accurately KNOW your fuel capacity and unusable fuel. 

Now that that tank is exactly at the unusable fuel level, I'd go through the process to level the plane and then drain the remaining fuel out of the "empty" tank and measure it carefully. That amount is truly your unusable fuel, regardless what the POH says.

I just recently did this with my 252. Leveling the plane involved about 1.5 inches of lift (plywood) under the mains and a little air out of the nose wheel.

For my purposes, I ran one tank dry, leveled the plane, drained the remaining fuel (1.5 gal) and noted that as the unusable. Then trained the other tank and added back 1.5 gal as being the unusable.

[carusoam]

Paul,

Any additional note, regarding fuel left between the sump drain, and the lowest inside corner of the tank?

There is that one unusable, and undrainable, area that concerns me about water and dirt that can be dormant for a while...

Best regards,

-a-

[gsxrpilot]

9 hours ago, carusoam said:

Paul,

Any additional note, regarding fuel left between the sump drain, and the lowest inside corner of the tank?

There is that one unusable, and undrainable, area that concerns me about water and dirt that can be dormant for a while...

Best regards,

-a-

Yes, my initial thought is that if it is unusable and undrainable then it's unknowable and must be ignored. And if dirt/water has accumulated there it's of such a small amount that it's insignificant, and regardless, can only be surely cleaned out by opening the tank which is a very intrusive, and paint ruining procedure.

If the tank is opened up, then all the contents of the tank can be removed/cleaned out. But then, the most accurate way to determine useable and unusable fuel would be to refer back to the numbers obtained after running the tank dry in flight.

Just my $0.02

[Bob - S50]

First a word.  We have an FL202 installed.  We initially did that with stock floats and it worked fine for awhile.  But as time wore on the readings became unacceptable due to normal deterioration of the old style wiper floats.  If you really want reliable readings, get the Cies floats and do that at the same time so you won't have to do the calibration again.  And if you are going to do that, I'd recommend you get the FL202D gauge rather than the FL202.  It costs just a bit more but Cies says you'll get more reliable readings than you will with the resistive gauge because it will not be as sensitive to a poor ground connection.  With that said...

Here's what we did.

Over several weeks I amassed and cleaned/dried enough containers (plastic gallon milk jugs) to hold 35 gallons of fuel.  Since each tank holds 32 useable gallons, we flew the plane until it had about 35 total left.  I then drained the fuel into the containers.  The quickest way would be a two person operation in which you disconnect the fuel line from the output of the electric fuel pump.  One person then feeds the hose into the next container while the other person turns the pump on and off as needed.  That's too easy for me.  I put a container with a funnel under the gascolator.  I then used two screw drivers to pull the ring on the floor.  One screw driver went through the ring and the other was located perpendicular to that screw driver such that it held the ring up.  When I could get no more that way, I drained fuel through the sump.  It only had a bit over a pint left.

Once it was drained, I borrowed jacks from our mechanic and leveled the airplane laterally and longitudinally and calibrated the gauge.  With gallon milk jugs and a funnel it was pretty easy to add two gallons at a time as specified in the procedure.

Once I had finished one wing I then started over by draining the tank I just finished so I would have fuel to calibrate the other tank.

Have fun.

[Gary0747]

It appears to me that the floats will be resting on their bottom stops with a significant amount of fuel remaining some of which is probably useable fuel.  I would think this should be the defining point for zero fuel on the gauges?

[gsxrpilot]

I have the CiES digital senders in my 252 and hooked up to EDM900 gauges. When the gauges go to zero, they X out. I know that at that point I still have about 1.5 gal of useable fuel in that tank.

I know this, not by measuring on the ground, but by running it dry in level flight and then refilling after landing.

[Bob - S50]

1 hour ago, gsxrpilot said:

I have the CiES digital senders in my 252 and hooked up to EDM900 gauges. When the gauges go to zero, they X out. I know that at that point I still have about 1.5 gal of useable fuel in that tank.

I know this, not by measuring on the ground, but by running it dry in level flight and then refilling after landing.

I did something similar.  I put in the required 1.25 gallons/tank of unuseable fuel as the '0' point on the gauge.  Some time later when it was convenient I went out and flew a tank dry.  After the gauge read zero the engine continued to run for another 5 minutes.  Some of the unuseable may be useable under the correct conditions.  Maybe not under other conditions.

[Gary0747]

I wonder if the resistive senders read down to 1.5 gal useable also?

[0TreeLemur]

1 hour ago, Gary0747 said:

I wonder if the resistive senders read down to 1.5 gal useable also?

When we calibrated the senders last year, the data don't show that effect.  The first 3/6 data points are pretty much on a straight line.

 

[Immelman]

Run the tank dry and start from there. No additional draining.

Unless you want unusable fuel on your gauge?

[Gary0747]

We were talking about how much useable fuel is remaining after the float senders hit the lower stops, which should be the zero point of the gauge.  CEIS appear to have 1.5 gallons below zero gauge reading. 

[Igor_U]

Yes,

I understand that running dry in flight should give you real unusable fuel qty in tank (I've done it years ago while calibrating my Home Depot paint stick to my tanks) but I believe it might be different than what TC calls for (15 lb total for F).

Maybe I'm just overcomplicating thigs and should proceed with calibrating the tank with no additional draining. Jacks would be ideal to level the plane, and I have them but issue is fuel truck would not refuel plane while in hangar. What a pain!  So, I might have to level it on apron and call the truck. I am not sure if they would be pleased fueling in 2 gallon increments, though.

Hence the idea to fly to nearby KAWO, and do it at the self-serve there, with half-ass attempt of leveling the plane.

I might take my IA's offer and use his 55 gal drum and hand pump, drain all the fuel, level on jacks and do all the works pouring out of 2 gal canister...

 

As for resistive senders vs. CIES:

I understand all the benefits and while my senders are OK now, also know they can go TU anytime... but, I really, really don't care to spend that kind money on 4 new CIES senders. I believe I'm better off using fuel flow and totalizer on my engine monitor and spend $$ on something else.

I've owned my plane for 14 years and over 10y monitored remaining fuel by stopwatch and was never off by more then couple of gallons on long flights (5.5-6h) so adding engine monitor before and now FL202, would just improve things.

My main reason installing (any) fuel gage was to remove original engine 6-pack (2.5 lb heavy!) and being legal.

 

Thank you.

 

 

[Igor_U]

Well, finally a follow up to this thread.

This Sunday new Fuel gage calibration was complete. I had 18 gal of fuel in RHS (LHS was run dry) that I wanted to burn down doing post ADS-B install flight however, PNW weather didn't cooperate. We transfer half of it to 35 gal barrel by my IA's fuel pump and rest was drained. So was 1+ gal from LHS tank. It shows that unusable fuel from TC is quite accurate.

We placed unusable back into tanks and started calibration. It turned out 32 gal is accurate capacity filling it to the brim. Plane was on jacks, leveled as per SM.

Aerospace Logic FL202 requires calibration from 0-32 every 2 gal. It took time, pouring 2 gal Jerry can and wait for level to settle - I could follow it on the gage. Old Resistive senders were reading unused fuel in tanks... and adding voltage reading with each 2 gal. Definitely not a straight line. 

It was quite a job for two people, transferring all the fuel out, calling FBO and convince them to pour in plastic barrel, transfer to 2gal can, the works. It was proper way to do it, though.

I'd still think it'd be faster to get the plane to self serve pump and jack it, pour in 2 gal increments but Self serve is broken for a year now at KPAE... 

Thank you. 

 

[M20F-1968]

I am still trying to sort out my Rochester gauges used with JPI930 and Monroy tanks.  

I ran the right tank nearly dry.  The JPI gives me a warning just before unusable fuel.  I know this since when on the ground I started adding fuel and going through the calibration process.  I only collected data and have not yet changed the stored tables in the JPI, but the fuel put into the plane was 47 gallons into the rgt tank.  That is what it is supposed to be per Monroy.  True, I do not know if the remaining fuel before filling was 1 gallon v. 1 1/2 or some similar number.  Not sure that is so important right now as I do not intend to routinely run the tank lower than the 47 gallons I saw.

My question is, what have others experienced when calibrating a tank with Monroy long range tanks since to curve is not linear at all.  Also, the number one is supposed to write down from the JPI at 0, 1/4, 1/2, 3/4 and full is somewhat variable.  How accurately does it sort out when thee numbers are stored into the JPI data?

John Breda

[M20F-1968]

Another thought I had is to fill the tank fully, then fly the plane recognizing that full usable fuel to the JPI warning is 47 gallons.  Then when flying in smooth air, calibrate the JPI at 3/4 (33 gallons), 1/2 (22 gallons), 1/4 (11 gallons) and "0" being the lowest JPI warning.  I would use the fuel totalizer to determine how much fuel is burned off.  The totalizer seems pretty accurate.

Also, I am unclear why the Cies senders are so much better.  In flight, the fuel is moving.  It would seem that either sender would be relaying data incorporating a range of data due to the fuel movement.  At best, the JPI will be depicting an average of those numbers.  For any one value, the digitally derived number may be more accurate, but given that you are measuring a moving body of fluid, is the average depicted on the JPI really that much more accurate?

John Breda

[Marauder]

Another thought I had is to fill the tank fully, then fly the plane recognizing that full usable fuel to the JPI warning is 47 gallons.  Then when flying in smooth air, calibrate the JPI at 3/4 (33 gallons), 1/2 (22 gallons), 1/4 (11 gallons) and "0" being the lowest JPI warning.  I would use the fuel totalizer to determine how much fuel is burned off.  The totalizer seems pretty accurate.
Also, I am unclear why the Cies senders are so much better.  In flight, the fuel is moving.  It would seem that either sender would be relaying data incorporating a range of data due to the fuel movement.  At best, the JPI will be depicting an average of those numbers.  For any one value, the digitally derived number may be more accurate, but given that you are measuring a moving body of fluid, is the average depicted on the JPI really that much more accurate?
John Breda

John - I am one that installed CiES senders with a JPI 900. Let me start with your question on the long range tanks. If your F originally had 64 gallons usable AND has 2 senders per side in their factory positions, the best you can hope for is your JPI to read full at the 32 gallon point - regardless how much of the Monroy tank is filled. The Monroy system uses the next wing cavity outboard and the location of the factory sender is on the furthest outboard bay of the original tank. So, when you fill the plane, until you burn down fuel below 32 gallons (all theoretical values at this point), you will read full fuel. This is what is happening with Bob B’s E model that only has 1 sender per tank.

I would calibrate it from the 32 gallons downward. But knowing you, you’ll have a DER out there trying to figure out where to install the sender in the Monroy tank.


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[Marauder]

Another thought I had is to fill the tank fully, then fly the plane recognizing that full usable fuel to the JPI warning is 47 gallons.  Then when flying in smooth air, calibrate the JPI at 3/4 (33 gallons), 1/2 (22 gallons), 1/4 (11 gallons) and "0" being the lowest JPI warning.  I would use the fuel totalizer to determine how much fuel is burned off.  The totalizer seems pretty accurate.
Also, I am unclear why the Cies senders are so much better.  In flight, the fuel is moving.  It would seem that either sender would be relaying data incorporating a range of data due to the fuel movement.  At best, the JPI will be depicting an average of those numbers.  For any one value, the digitally derived number may be more accurate, but given that you are measuring a moving body of fluid, is the average depicted on the JPI really that much more accurate?
John Breda

John - speaking from first hand experience with factory original and replacement CiES senders. The factory senders had a few issues on the JPI. The first being they weren’t very linear nor reproducible. In flight, this would lead to this error being seen frequently:



Since the JPI is expecting the fuel used on a tank to match fuel remaining based on sender position, I saw this error routinely. Could be the sender was sticking as it was sloshing around or just a bad spot on the resistor surface. Whatever the cause, I saw it frequently but have never seen it with the CiES.

With the CiES and the JPI, the values are extremely accurate. Although the fuel quantity is represented as whole values, Bob B pointed out the JPI raw data was in decimal format. Sure enough, when I saw 17 gallons remaining and I thought it should be 18, it is a rounding thing going on. After operating these senders for a couple of years, if the CiES is off more than 0.5 gallons, it was the human filling the tank who made the mistake and not the senders. They are just that accurate.

I also wanted to respond to your question about the sloshing around of these senders. I have never seen an issue with erroneous quantity levels with the CiES. Maybe they are doing averaging or that since they are new floats, come back to the fuel level quickly, I just don’t see dancing fuel quantity like I did with the factory senders.


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[Marauder]

I should add a comment about the photo above. This picture was taken on the burn down flight just before installing the CiES. I was burning down both tanks to roughly 5 gallons so I could drain the rest and install the CiES. When I took that picture, I had burned the fuel on the left tank down to 6 gallons on the display when that 21 gallon quantity showed up. You can see the concern.


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[ArtVandelay]

I should add a comment about the photo above. This picture was taken on the burn down flight just before installing the CiES. I was burning down both tanks to roughly 5 gallons so I could drain the rest and install the CiES. When I took that picture, I had burned the fuel on the left tank down to 6 gallons on the display when that 21 gallon quantity showed up. You can see the concern.

The factory resistance senders can do this and it’s a sign they need to be overhauled. You can check them before by simply hooking up a ohmmeter and slowly move the arm, readings should be consistent and linear.


Tom

[Igor_U]

From your posts it seems to me that JPI needs senders to be calibrated in 1/4 of a tank increments. Is that correct? Aerospace logic gage calibrates in 2 gallon increments.

Reason for asking is how can you assure "extreme accuracy" you all claim? It seems to me that within 8 gal range (32/4 for M20F tank) CSIS sender (like any other) with JPI would approximate linearly the capacity for the signal value regardless of the fuel tank. It is a shape of the tank (and sender location) that should define the fuel level curve relation to signal level. John's example with Monroy tanks is good example.

What I am missing here?

 

Thank you.

 

[Marauder]

From your posts it seems to me that JPI needs senders to be calibrated in 1/4 of a tank increments. Is that correct? Aerospace logic gage calibrates in 2 gallon increments.
Reason for asking is how can you assure "extreme accuracy" you all claim? It seems to me that within 8 gal range (32/4 for M20F tank) CSIS sender (like any other) with JPI would approximate linearly the capacity for the signal value regardless of the fuel tank. It is a shape of the tank (and sender location) that should define the fuel level curve relation to signal level. John's example with Monroy tanks is good example.
What I am missing here?
 
Thank you.
 

There are 5 calibration points for the JPI 900 fuel gauges. The calibration assumes linearity and my experience with the 54 gallon bladder system is that it is.

The factory original senders are located inboard and on some models a second sender on the outboard of the outer bay (64 gallon planes). With the Monroy system the next outer bay is used, beyond the second sender and also further up the wing dihedral. I don’t think that the sender is moved out to the end of the extended tank (and that is what John is asking) and thus the tank gauge will read full until the level gets below the outboard sender’s position.

If the sender is moved to the outside of the outer bay, then there is a long distance between the outboard and inboard senders which would require a linear drop for the gauge to measure.


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[ArtVandelay]

And heres me putting in my JPI 830 and thinking it was all going to be plug and play.  Oh well, looks like a big bill will be coming from Aeroskill for all this calibration lark.  
Andrew (aka the replusive one). 

830s don’t monitor fuel levels....you’ll need the 900 for that.


Tom