Extended Range Fuel Tanks - Acclaim (Question)

[Bentonck]

I know one of you will know this so I'm going to ask here after suffering some confusion yesterday...

My Acclaim was originally R242RJ which was exported to Brazil and rebranded PT-ALN.  It is Serial No. 30-0015 and in the original POH it has the Flight Manual Supplement for the 106 gallon extended range tanks.  Inside the cockpit, the Fuel selector on the floor shows each tank at 51 gallons (usable) which is correct for the plane.  The placard is correct.  

On the G1000, when you reset the fuel it shows 102 gallons usable.  Up until this, no problems.

My issue is, on the G1000 Engine page, the tanks both show "full" at 45 gallons and they start down from there when you start the engine.  The plane was repainted in Brazil and they painted the fuel info onto the wing where there would normally be a decal, and it shows (in Portuguese) 44,5 gallons usable each side, 89 total (which would have been correct without the extended range tanks but is not now, I believe).... so the fuel selector and G1000 fuel computer show 102 gallons, and the fuel gauges and wing decals show 89... 

We flew 4.7 hours yesterday and I burned up 73 gallons of 100LL (that's how much went in when we arrived) ... the fuel gauges in the plane were showing 20 gallons left, and the fuel tabs on the wing were showing 20 gallons left (the gauges you use to partially fuel) ... so basically I want to know if I am correct in assuming that these were not calibrated with the larger tanks when installed and, in fact, I had 29 gallons left in the tanks total....or.....I only had 16 gallons out of 89 which would leave me a bit uncomfortable... does someone know this?  Also, is there someway to change the gauges in the G1000 to show them with 51 gallons usable a side instead of 44.5?  This would make me feel a lot more comfortable when I look at them....  I think about 5 hours is as far as I'll ever want to go at one sitting but I would like to know that I have another 90 mins of fuel left when I get there...had I got stuck in bad weather with a hold and the gauges were in the red the pucker factor would have been very high.  16 gallons is about my personal minimum.  Weather was good yesterday or I would have stopped for fuel anyway.

I just want to know how I confirm the 102 gallons and if I can reset the G1000 somehow to reflect this.

Thanks in advance,

Benton

[tmo]

Run one tank down, fill up, repeat other side.

[carusoam]

You have defined a classic Mooney challenge, Benton...

Standard Ovation tanks are technically 102 gallons or so...

But filling them requires being on a perfectly flat surface.... and waiting for air bubbles to escape through tiny vent holes between ribs... Finishing by slowly filling to the top, waiting, filling, waiting.... spilling... waiting... click again.... kind of patience...

The fuel will be at the top of the tank, and above the filler neck...

Filler necks in some Mooneys have been intentionally modified to keep more air at the top of the tank...

Using the 89 gallons as placarded is a safe way to go....

extra ten gallons in doesn’t harm anything.... except weight and balance....

There are two ways to monitor fuel use with accuracy...  FF/totalizer and Cies Fuel level instruments...

 

As an owner... you get to calibrate or check the calibration of each device when you first get the plane...

You won’t feel comfortable until after you have done these steps...

 

Once everything is calibrated... your trust level goes way up with the accuracy you have...

Keep in mind...

• some gauges are calibrated with a nose-up attitude caused by being on the ground... (great for filling)
• others are accurate while level in flight... (Great for flying)
• The fuel pick-ups are at the back of the tank... inboard. (Good to know to best fully empty a tank)
• Extended tanks for the long body have 130gallons useable...
   

PP thoughts only, not a mechanic...

Best regards,

-a-

[kortopates]

Benton,

As Anthony described above, what you describe is not the "Monroy Extended Fuel Tanks" option that adds 30 more gallons with an additional fuel bay, but instead you should have a filler neck modification per the attached AFMS below (which should be in your POH). And from what you describe, it sounds like the modification is complete in that G1000 allows you to set Remaining fuel to 102 Gal. But before we go further, recognize you have two independent measurements of fuel: i) Fuel remaining which is merely calculated by subtracting your indicated GPH FF from your starting Remaining fuel which you can reset or add fuel to each time you start. Entirely separate from this is your tank fuel levels being sensed from your fuel tank senders. These were calibrated originally for 89 gal tanks by the factory and a G1000 Calibration config file was loaded at the time of G1000 s/w installation. You're not the first G1000 Mooney to report your tanks still only show 44.5 Gal or 45 at full, so I suspect the filler neck mod did not also provide a different fuel tank calibration.  Garmin provides a calibration procedure calibrating the fuel tank senders. But its unclear to me whether only Mooney can create or modify your 89 gal config file into a 102 gal config file of if any Garmin dealer can do it for you. You would have to ask Mooney or any Garmin authorized dealer if they can re-calibrate your fuel tanks. You also have the option of installing much more accurate CIES fuel senders that Anthony mentioned above. 

However what you state here "the tanks both show "full" at 45 gallons and they start down from there when you start the engine" - that really shouldn't be entirely true. The fuel level gauges should remain at 45 gallons, and continue to indicate full, until the fuel level actually drops down to below 45 gals. In other words you shouldn't really see any decrease in flight till you have burned off 6 gallons on any given tank if they indeed where filled all the way upto 51 gallons. As far as your fuel senders are concerned, you overfilled the tanks and after you burn off 6 gallons the fuel senders will be at precisely the same location they were before with only 45 gal before your filler neck mod that allowed putting in the extra 6 gallons.

You might want to confirm how much you're really carrying by starting out with a completely drained tank, adding in unusable fuel and then filling to verify how many gallons you can actually add to the tank to verify true full capacity. That will give you the confidence of how much fuel your carrying. 

Remember the fuel tank levels on the G1000 are calibrated only for "in flight" while  level - not on the ground. And the Wing tank gauges are only calibrated for on the ground (where is nose is 3-5 degrees up).  

51_GALLON.pdf

[Danb]

My G1000 was changed from 90 gallons to 130 by the  MSC center that installed the Monroy extended range tanks. It only takes a few minutes to change in the configure files. 
Fill up remember to set tanks to correct amount when full I set 120 gal giving another buffer. As flying the digital readings in mine are spot on as is the range ring, the two fuel indicators don’t move or recognize the used fuel due to the senders being in the original tanks not knowing about the Monroys, when each tank approach say 45 gallons then they become useful mine are correct at that point. I always chart my fuel used during the flight this is done every time I switch tanks. This information gives me confidence I can rely on the readings as depicted. 

[Bentonck]

Thanks everyone for your input.  I understand now, the 102 gallons is technically the same tank as the 89g, it's just a different fuel neck which allows you to stuff a few more gallons in there, all going well, weather and angles permitting....

I understand the fuel senders should be correct and the gauges will only start down once I have burned off a few gallons.  I'll watch that a lot more carefully on the next flight and see.

[Yooper Rocketman]

10 hours ago, kortopates said:

You might want to confirm how much you're really carrying by starting out with a completely drained tank, adding in unusable fuel and then filling to verify how many gallons you can actually add to the tank to verify true full capacity. That will give you the confidence of how much fuel your carrying.  

Like Paul said, but a little tip.  I've calibrated the fuel tanks on my Lancair 4 times.  I won't go into why, but suffice to say I thought accuracy on that was an absolute safety issue.

We always pulled the fuel line off the delivery side of the fuel pump and pumped the fuel off (draining was just too messy).  We pumped until the fuel flow decreased enough we knew we couldn't rely on the engine running on what what the diminished  flow was.  AT THAT POINT, we then drained the remainder of the fuel from the tank and measured that as "unusable".  We reinstalled the unusable quantity, then programmed my Garmin G3X after every 5 gallons was added, until reaching the full point.  Not sure how the certified Garmin products work, but the G3X allows programming as many points along the fuel level curve as you want, which gives incredible accuracy (and confidence) during flight.

Tom

[aviatoreb]

Sort of on topic - I have seen for some time that the CIES fuel system is the gold standard for accuracy.

When I look it up it is not so clear what comes with the kit.  On spruce for a K its about $1750 for the kit.

-Is that just for the sensor - does that feed to the current needles/display already in my airplane?  Or is there some other place to display the reading?

-What is involved and how much time is it to install one of these bad boys?

E

[Yooper Rocketman]

4 hours ago, aviatoreb said:

Sort of on topic - I have seen for some time that the CIES fuel system is the gold standard for accuracy.

When I look it up it is not so clear what comes with the kit.  On spruce for a K its about $1750 for the kit.

-Is that just for the sensor - does that feed to the current needles/display already in my airplane?  Or is there some other place to display the reading?

-What is involved and how much time is it to install one of these bad boys?

E

I can’t answer your specific question Erik, but I can opin as a guy flying behind fuel gauges of both types.  
 

IT’S PROBABLY IN THE TOP FIVE of improvements moving to my new plane.  Comparing fuel monitoring between factory gauges and my G3X,  I think the only thing close to comparing it is a cave man hammering a crude chisel on a chunk of rock to a modern machine shop CC machine cutting the same stone.  
 

Knowing what I know now, I would place converting to CIES sensors to the top of ANY  “want list”!!!  The safety aspect and peace of mind is beyond measurement.

Tom

[aviatoreb]

1 hour ago, Yooper Rocketman said:

I can’t answer your specific question Erik, but I can opin as a guy flying behind fuel gauges of both types.  
 

IT’S PROBABLY IN THE TOP FIVE of improvements moving to my new plane.  Comparing fuel monitoring between factory gauges and my G3X,  I think the only thing close to comparing it is a cave man hammering a crude chisel on a chunk of rock to a modern machine shop CC machine cutting the same stone.  
 

Knowing what I know now, I would place converting to CIES sensors to the top of ANY  “want list”!!!  The safety aspect and peace of mind is beyond measurement.

Tom

Wow - that is quite an endorsement.

I have been figuring the way to make up for poor gauges, is simply almost not relying on them at all.  So tracking fuel flow rate in the edm together with the habit of way over shooting it/ tinkering more fuel than necessary by a safety margin and a safety margin on top of that.

...hmmmm CIES.  Maybe coming to near "the next thing".

OK folks - back to the practical - anyone here done it to a mooney.  How many hours to tally vs the $1750 hardware kit price tag?

[GeeBee]

Gauge hysteresis has been around as long as there have been electrons and will continue. I remember we got fancy new electronic capacitance gauges on the 727 and while they were better, they still had some hysteresis. I always calibrate the hysteresis in the gauges and verify the K factor on the flow. Here is an example. I keep this spread sheet in my airplane. Note the flow method is spot on the money.

 

[carusoam]

Erik,

The key thing is how many floats does your plane have?

The 52 gallon tanks only have one float per tank...

The 102 gallon tanks have a pair for each tank...

What does your K have... I would expect two...

At the other end of the fancy floats is a digital indicator... if you have a JPI900... that works really well....

Awesome Pirep for @fuellevel our Cies guy... (above)

Best regards,

-a-

[tmo]

At a risk of stating the obvious, fuel flow alone will not account for loss of fuel due to unforeseen issues - be it a missing cap, a cracked line, or something like that.

[aviatoreb]

5 hours ago, tmo said:

At a risk of stating the obvious, fuel flow alone will not account for loss of fuel due to unforeseen issues - be it a missing cap, a cracked line, or something like that.

Right!  Not to mention a newly developed fuel tank leak could make for a nasty surprise if relying entirely on fuel flow.  E.g. over say several weeks with memory on fuel flow suggesting 20 gal remaining....but a few gallons left behind on the hangar floor maybe?

[carusoam]

We discussed a comparator to match Fuel totalizer numbers to fuel level numbers... and alarm if the numbers didn’t agree... (within a range)

The power of the Cies system is quite awesome.... for its flexibility...

This may go back a few years while Cies was still developing their float system.... 
 

Essentially, with the Cies system, and the fuel totalizer, you have a method to verify that your totalizer is telling you the truth...
 

The Cies can back you up in the event you depart without resetting your totalizer....

PP thoughts only, stuff I read about around here...

Best regards,

-a-

 

[Geoff]

My 2007 G1000 Acclaim has the Monroy 130 gal tanks.  I don't have it handy but buried  in the STC paperwork it states that:

Standard fuel gauges 22 gal = 22 gal actual

Standard fuel gauges 33 gal = 44 gal actual

Standard fuel gauges 45 gal =  ?? can't remember

The standard gauges get more accurate the less fuel you have remaining.  When you are at the bottom of the range they are very accurate.

So there is some truth to the gauges needing "calibrating" whether that is manual or done in the G1000 config file is up to you.

  

[Danb]

Geoff, Id believe STD gauges read 45 gal= 45 to 65. Based on my charting I agree with your readings.

I chart my fuel gauges, totalizer reading per side with actual on every long cross country.

[carusoam]

So... I went looking for the 130 gal STC.... In my collection...

That got away...

But I did find the one somebody asked about the other day....

50galuseablefuelrtn.pdf  (45 to 50 gal per side)

And of course... the copy out my books collection only captures part of the name...

So... here is a copy of the first page... there may be enough here to help find a similar STC doc for the 130gal....

 

Best regards,

 -a-

 

MOONEY AIRPLANE COMPANY, INC. LOUIS SCHREINER FIELD KERRVILLE, TEXAS 78028
FAA APPROVED
AIRPLANE FLIGHT MANUAL SUPPLEMENT FOR
MOONEY M20R, M20TN
WITH
50 GALLON CAPACITY USEABLE FUEL TANK CONFIGURATION INSTALLED
MODEL NO. _______________________________________________________________ REG. NO. ________________________________________________________________ SERIAL NO. ______________________________________________________________
This Supplement must be attached to the FAA Approved Airplane Flight Manual when the 50 Gallon Fuel Tank configuration is installed in accordance with Mooney Drawing Number 210217. The information contained herein supplements and / or replaces the information of the basic Air- plane Flight Manual. For Limitations, Procedures and Performance information not contained in this Supplement, consult the basic Airplane Flight Manual.
 FAA APPROVED:
DATE:
Michele M. Owsley
Manager, Airplane Certification Office FEDERAL AVIATION ADMINISTRATION 2601 Meacham Boulevard
Fort Worth, Texas 76137-0150
   CopyrightE 2008 All Rights Reserved Mooney Airplane Company - Louis Schreiner Field Kerrville, Texas 78028
SUPP0018
 Original Issue: 02-1-08
1

[FloridaMan]

I'm a big fan of the wing mounted gauges combined with a fuel totalizer. When the needles stop bouncing, you've got less than 10 gallons. Funny thing is, when I bought my Rocket, the panel mounted stock gauges were spot on and I can't seem to get the JPI gauges to calibrate worth a damn even though the senders are the same. 

[Niko182]

Just now, FloridaMan said:

I'm a big fan of the wing mounted gauges combined with a fuel totalizer. When the needles stop bouncing, you've got less than 10 gallons. Funny thing is, when I bought my Rocket, the panel mounted stock gauges were spot on and I can't seem to get the JPI gauges to calibrate worth a damn even though the senders are the same. 

Cies ones help a lot

[FloridaMan]

Just now, Niko182 said:

Cies ones help a lot

Signature at Key West jammed my fuel cap in my M20F by not installing it straight. It took a lot of force to remove it. So, not only did I have the ordeal of purging the water from the tank from when it rained (took several full cups of water when I sumped it to get a blue line at the top, et cetera), a month or so later one of the lugs broke off of the cap, most certainly related to the cross-threading of the cap. A passenger in the backseat spotted the fuel pouring out over the wing on the takeoff roll. There are ways that you can lose fuel in flight and the next best thing to having a window to see inside the tank is to have those wing mounted dials. 

[Bentonck]

On 6/9/2020 at 5:34 PM, Geoff said:

My 2007 G1000 Acclaim has the Monroy 130 gal tanks.  I don't have it handy but buried  in the STC paperwork it states that:

Standard fuel gauges 22 gal = 22 gal actual

Standard fuel gauges 33 gal = 44 gal actual

Standard fuel gauges 45 gal =  ?? can't remember

The standard gauges get more accurate the less fuel you have remaining.  When you are at the bottom of the range they are very accurate.

So there is some truth to the gauges needing "calibrating" whether that is manual or done in the G1000 config file is up to you.

  

That's it...after talking to Deb and reading through all this I went and tested.  The gauges show 44,5 (let's call it 45) full....they work their way down, when the fuel totalizer get's to about 40g left, it starts matching the gauges, before this the gauges show less than the totalizer.  I landed with about 35g left and everything matched up, the fuel totalizer on the G1000, the G1000 fuel gauges, and the physical when I checked.  So it takes off with 102 gallons and the G1000 will keep track of it (as long as you reset the fuel ... ) 

102g full leaves me enough UL for me and the wifey....pretty much exactly.  With 130g it would be me and MAYBE enough UL left over for a can of coke or a stick of gum...