Long Range Tanks

[blakealbers]

Hello,  I have a 93 Mooney Bravo that I purchased back in July.  It is equipped with long range tanks which of course have a long range supplemental guide in the POH and it came with a piece of note pad paper where they completely drained and refilled the tanks noting fuel put in and indicated fuel.  Supplemental says the cockpit gauges indicate the proper amount of fuel up to 22 gallons while this note pad from when a mechanic slowly filled tanks does not.  Any thoughts appreciated, hate not knowing exactly how much fuel is on board. 

[Parker_Woodruff]

Is this assuming the plane is on the ground?  What's the usable fuel in the M20M and was there unusable fuel already in the tanks when the fuel was "drained".  In other words, does "completely drained" mean they siphoned out all the unusable fuel?

 

You'll likely catch my drift.  Also, the plane might read differently on the ground and in the air.  How do the sight gauges compare on the ground?

[Danb]

Blake..that's at least some useful info. I also have long range tanks with no supplement on what they thought the gauge should read, my gauges are not accurate until about 30 gal. Hopefully you have a fuel totalizer or computer...I'd just keep a close eye on the gauges on the wing and compare to the ones on the panel also don't depend on them keep track of what u put in what your flows are and time flown and when you reach your 22 gal. You'll probably be in agreement..you need to gather the correct info in order to rely on.

[carqwik]

Somewhere I recall learning that the site gauges on the Bravo (the factory installed ones...that is) are only valid on level ground whereas the ship's fuel gauges are not valid on the ground (but are valid in flight...go figure since they have never worked exactly right anyways).  I have no idea how the sight gauges are impacted by the long range tank install so perhaps my post is kind of worthless in response to the original post.

[carusoam]

There is no easy answer to this question.

To be ultimately accurate, it takes draining and refilling while taking notes...

Even if the tanks were identical new from the factory, you would need this exercise.

Over the years...

1) The collars at the top of the tank have changed design... Some intentionally limit max fuel volume.

2) It is possible that they have been changed out for better venting...

3) increasing tank volume, the new volume is uphill compared to the original volume. This makes the existing level system challenging... This changing geometry is less than linear compared to the gauge.

4) the usable solution includes a well calibrated FF and Fuel totalizer device. Check the k factor on yours.

How much volume do you have?

Other Long bodies have standard volume from 75 to 100 gals useable. Some extended tanks add another 15gal per side...consider these to be approximate numbers.

Know your weight and balance numbers regarding fuel levels...

Hope that helps and welcome aboard,

-a-

[Danb]

Blake as I trie to state our Bravos came with fuel gauges for 89 usable gal. Now you either have Monroe 100?120 or 130 gal tanks mine to the tips are 130, that being our fuel gauge has no idea you have 2 extra bays leading into the 2 original bays of which the original gauges are set for.lthe reason someone tried to show there calibration in relation to the original gauges...reason for my 1st response. Prior to the long range tanks my gauges on the wings and inside the plane along with the gauges on my G 1000 all agreed..,but i changed the area holding the fuel by using an extra bay on each side

[M016576]

If you're flying where 1-2 gallons makes a difference, you're cutting it too close in my books-

These fuel senders and gauges are not accurate. Even a "perfectly calibrated" totalizer won't tell you exactly how much gas is in your tank- although it may be close.

In my experience, best practice is to add enough gas for your mission plus at least the required reserves (IFR or VFR). Use the gauges to "back yourself up," With fuel burn / fuel flow over time.

If there's already fuel in the tanks then be more conservative in your fuel addition (ie add a bit more than you think you need) rather than less so.

If you Absolutely must know to appeas an OCD tendency, then drain your tanks bone dry by removing a fuel sump, and then refill and test them out yourself over time. Make sure you remember what your "empty" fuel state is on the gauges, and remember to note exactly where your "full fuel" point is so you can refill to that spot every time.

All in all, just realize that with the hardware that's out there, while its "close enough", you're still cutting butter with a chainsaw.

[carusoam]

Know that you may be among other OCD people here...

They have developed personal calibrated sticks specifically for their tanks.

They use the phrase 'stick the tank' to refer to knowing how much they are starting with.

A few important things to know while flying.

1) how much fuel is on board before you start...

2) how much fuel has been burned as you go...

3) how much fuel does it take to get to the target...

FF integrated with a GPS is a very helpful addition to level gauges that are most accurate (by definition) when empty.

Best regards,

-a-

[carusoam]

Taking my third try at answering...call me OCD...

There are new fuel level displays available. (See JPI and others for these)

Your previous owner bought half of a two part system.

1) he added the extra volume he wanted, but didn't get new fuel level displays in the cockpit. Most people would do this as well...

2) he did something that works, mathematically equate what the gauge is reading to what is actually in the tank. Most people would do this as well...

Good news...

Using what you have tells you exactly what you want to know!

Now, verify it to make sure this is the right data to match your current tanks. Wrong place to make a simple mistake...?

Now realize how challenging it is for fuel level sensors to know how much fuel is really in the tank, when the tanks are missing the constant geometry attribute...?

Now you understand the importance of an accurate fuel totalizer. Two floats in the varying geometry tank can never be as accurate as a fuel totalizer.

Knowing how much you are starting with is important if you are not full up. Back to your calibration sheet for this...

If you are really OCD...

1) you always fill your tanks before you zero the fuel totalizer. Could lead to W&B challenge...

2) you check the exterior gauges and the interior gauges to make sure they are not in disagreement...

3) stick the tank...

You have created three ways to make sure the fuel is still there before you depart.

Do you feel you are not alone?

[Danb]

Carsusoam I don't think your ocd. Just competent , fuel starvation should NEVER occur.yuor probably redundant in lots of things..things like flying w/ 2 IPads maybe local charts for additional backup, extra flashlight, handheld, maybe PLB..I'd be surprised by your posts if you weren't cautious and competent...good lesson for all of us..

[aviatoreb]

This is a very interesting thread for me since I do not have long range tanks and I am likely to have them installed during this next year when I get a chance.

 

I am trying to infer what the two different kind of fuel gauges will read as the now two sets of tanks feed.  Its easy as pie now - put in 38gal per side (full usable per side - and I know if I fill it to the rim - giggle the tanks and then fill then giggle, eventually I get just a bit more than 38 - or 76 usable total from prior measurements of empty).  And my gauges ready roughly linearly from there.

 

How would I expect my gauges to read ideally with LR tanks installed?

[Danb]

Erik ideally correct except I do not know how or who makes gauges which would read correct since we're adding fuel to an area not originally designed for. Blake has his cheat sheet since it was there ...I was advised by Premiere when they installed the Monroy why they would not read as prior. I know when I,m flyin what my fuel is when my gauges near 30 gal I can rely on them prior Based on experience I know how much I have...you know your plane and won't even worry about the early error. BTW it was the best $$$!I have spent on any items for any of my planes in 30 yrs of ownership..in the long run they will pay for themselves. When we is bad it's awesome to fly at our speeds for 7 hours without landing in need be.. You can always land if you choose ..good luck and go for it..

[aviatoreb]

Erik ideally correct except I do not know how or who makes gauges which would read correct since we're adding fuel to an area not originally designed for. Blake has his cheat sheet since it was there ...I was advised by Premiere when they installed the Monroy why they would not read as prior. I know when I,m flyin what my fuel is when my gauges near 30 gal I can rely on them prior Based on experience I know how much I have...you know your plane and won't even worry about the early error. BTW it was the best $$$!I have spent on any items for any of my planes in 30 yrs of ownership..in the long run they will pay for themselves. When we is bad it's awesome to fly at our speeds for 7 hours without landing in need be.. You can always land if you choose ..good luck and go for it..

 

Hi Danb,

 

Thanks - yes I am convinced!  I was going to have it done at my favorite MSC in Lancaster THIS MONTH, but I waited too long - they say it should ideally wait for spring warmth so that the sealer can cure properly.  That is when I will likely do it.

 

But I want to be 100% sure I understand what you are saying so forgive me for repeating.  Does it work like this with current gauges - gauges remain reading as full since they are reading off the original tanks, even though there may be lots more fuel in the aux tanks, until the aux tanks are empty so then as you say by then the main tanks will be down to roughly 30gal each and then you take those original gauges to be roughly accurate?

 

Except you have a Bravo - and how much again are your original tanks volume?  So 30 is somewhat below full even in the mains, right?

 

It must get kind of confusing to fly around with half tanks often.  To make weight sometimes I will not be able to fill lr tanks.  So I will likely spend a good bit of time with half tanks and after several flights with partly filled tanks, and partial refilling only part way and so forth, it must take some pretty good book keeping to keep an accurate idea of how much fuel is actually there.  As opposed to dirt simple as I do now which is essentially fill up before each flight (or often after each flight).  I guess I am a math professor so I am supposed to be good at adding and subtracting numbers, right?  :-)

[Danb]

I know your in good hands with Dorn we just missed each other a few months ago when he asked if I knew you, I had good experience getting it done down Ft Laudwrdale I had Premiere do my work until my warranties ran out the back to Lancaster been going to Henry Webers since 1985,,,but I had a leakage when I got home from Premiere and believe it or not they sent up a mechanic for 3-4 days and worked on the tanks in my hanger at no charge..I may have Premiere do my next annual only to get a new set of eyes on my bird, Weber has done the last 6 annuals so I may skip one yr. I also think Monroy is based in Lauderdale but not sure if you have any questions give me a jingle..

[aviatoreb]

I know your in good hands with Dorn we just missed each other a few months ago when he asked if I knew you, I had good experience getting it done down Ft Laudwrdale I had Premiere do my work until my warranties ran out the back to Lancaster been going to Henry Webers since 1985,,,but I had a leakage when I got home from Premiere and believe it or not they sent up a mechanic for 3-4 days and worked on the tanks in my hanger at no charge..I may have Premiere do my next annual only to get a new set of eyes on my bird, Weber has done the last 6 annuals so I may skip one yr. I also think Monroy is based in Lauderdale but not sure if you have any questions give me a jingle..

 

Hi Dan,

 

I am going to give you a jingle.  :-)  Please check your PM.

[Bob - S50]

Blake,

 

If you want to know how much fuel you have while airborne I might suggest you buy and install a digital fuel gauge.  There are a couple available.  We installed the Aerospace Logic FL202 in ours.  Current selling price is $652.

 

To calibrate you put the airplane in a level flight attitude.  This may require the use of jacks on the ground.  You drain the tanks and put in the unusable fuel.  You then tell the gauge that the tanks are empty.  You then add 2 gallons and tell the gauge you've added two gallons.  You continue to do this until the tanks are full, or in your case until adding more fuel does not increase the indication any more.  The gauge will then be accurate from that level down to zero.

 

If you are filling through the aux tank fill port, be sure to allow enough time for fuel to stabilize between tanks before you tell the gauge you've added the 2 gallons.

 

We also use a Fuel Stick Master which we purchased and calibrated one gallon at a time.  We did this so we know what we start with.  We also have the fuel flow option on the JPI EDM730 so it can show us fuel remaining.

 

Good luck,

 

Bob

[Awful_Charlie]

I wrote up the method I use at http://mooneyspace.com/topic/13384-low-fuel-l-r-warning-light/?view=findpost&p=171883

 

That works out good enough for me, and save having to jack the aircraft at the pumps (or carrying tankfulls of fuel around in cans)

[blakealbers]

Appreciate all the comments guys! I see this is not a unique concern. Ihave 59 a side max so the "120" conversion from monoroy.  Like i said i was just curious to why the Monoroy supplemental was different than as someone referred to it earlier the "Cheat sheet."  It may be that monoroy supplemental insert into the POH read off the inside gauges with the aircfraft on its wheels as apposed to jacked up and level like the note card. 

[carusoam]

The nonlinear uphill and curved shape must make it pretty difficult to measure fuel volume with the two old original float sensors.

Will you be flying long enough distances to want the programable sensors somebody mentioned above?

Best regards,

-a-

[M016576]

The nonlinear uphill and curved shape must make it pretty difficult to measure fuel volume with the two old original float sensors.

Will you be flying long enough distances to want the programable sensors somebody mentioned above?

Best regards,

-a-

Are there two per tank in a bravo? My two J's both had 2 senders per tank.

[Awful_Charlie]

Yes, there are two senders per tank. If the outboard one sticks (mine do), then full tanks indicates just under 33USG when full. (I don't have the long range option). A gentle thump under the sender releases it after refuelling

[blakealbers]

No my trip profile doesnt require ultimate fuel management.  I just wanted to know if when i have 22 gallons do i have 22 or do i have 30 a side which is the discrepancy.  

[donkaye]

This is a very interesting thread for me since I do not have long range tanks and I am likely to have them installed during this next year when I get a chance.

 

I am trying to infer what the two different kind of fuel gauges will read as the now two sets of tanks feed.  Its easy as pie now - put in 38gal per side (full usable per side - and I know if I fill it to the rim - giggle the tanks and then fill then giggle, eventually I get just a bit more than 38 - or 76 usable total from prior measurements of empty).  And my gauges ready roughly linearly from there.

 

How would I expect my gauges to read ideally with LR tanks installed?

 

---------------------------------

 

If ever there was an airplane that I would NOT add long range tanks to it would be the Rocket with it unique weight and balance envelope.  As it is, with 2 people and some baggage you are OUT of the envelope with 78 gallons.

 

Personally I would NEVER put long range tanks on my airplane.  In addition to not filling the tank every time after a flight which could lead to sealant drying out and future leaks, the closest I ever came to have a fuel problem was in ferrying a Bravo with long range tanks where the shop said there was one amount in the plane but the Red Light coming on very early said another.

[Danb]

I would feel if one relied on what a person put in my plane ferried or not would fall completely on the pilot who's responsibility for one in knowing fuel and all aspects of what's in the plane especially if being ferried..Therefore I don't see why one would not put long range tanks in a Bravo the one plane in the fleet which needs them the most, I hate being critical to a so called expert.i'v had long range tanks in my Bravo since 2006 with no sealant problems which have been vastly improved since the turn of the century. It is very easy determining what is in the tanks pre take off...

[Bravoman]

My plane has the long range tanks(120 gal total) and I rarely use the extra capacity. It also takes a while for the fuel to settle in when refueling which is a bit of a pain. Does anyone else experience this?