O&N bladders (stupid question #53)

[Cloudmirth]

My current M20C is my first Mooney with bladders.  I understand there is tube which connects the left and right tanks.  Now for the stupid question.  Because of the tank interconnection is my assumption that both tanks are feeding the engine regardless of the fuel selector position correct?

[carusoam]

Time to review your plumbing drawings...

Your fuel cells have little to do with how they are connected to the fuel selector valve...

You have two tanks... L & R...

they get plumbed directly to the fuel selector valve... choices are L, R, off...

See if that helps?

Or are you discussing how things are interconnected within the wing?

Check your drawing either way...

Best regards,

-a-

[takair]

8 minutes ago, Cloudmirth said:

My current M20C is my first Mooney with bladders.  I understand there is tube which connects the left and right tanks.  Now for the stupid question.  Because of the tank interconnection is my assumption that both tanks are feeding the engine regardless of the fuel selector position correct?

There should not be an interconnect.  As Anthony said, it connects to the fuel selector valve.

[A64Pilot]

There are separate, independent bladders that are connected to each other in each wing.

I have three in each wing and I believe on a J model that there could be four.

[David Lloyd]

In the C with the 54.8 gallon total usable bladders, there are two interconnected bladders in each wing.  Left and right wing fuel is not connected to each other.  In the F and J, there are three bladders in each wing for a total of 64 gallons usable.   There have been a few C/D and E with 64 gallons and a few F with 54.8 but these are rare.  

The 54.8 gallon bladder installation eats up 29.8 pounds of useful load.  Don't know about the 64 gallon.

[Cloudmirth]

Thanks for the very lucid explanations. Obviously I misinterpreted the use of the term interconnect that I had seen somewhere in reference to the bladders.  The fact that each tank feeds only the fuel selector makes perfect sense.

[carusoam]

If you find file leaks with your bladders...

The hose clamps connecting things together probably need to be tightened...

These would be the interconnects you may be reading about...

They are not known for leaking, so you probably won’t need to review this until many years go by...

PP thoughts only, not a mechanic...

Best regards,

-a-

[A64Pilot]

On 3/18/2021 at 8:16 PM, David Lloyd said:

In the C with the 54.8 gallon total usable bladders, there are two interconnected bladders in each wing.  Left and right wing fuel is not connected to each other.  In the F and J, there are three bladders in each wing for a total of 64 gallons usable.   There have been a few C/D and E with 64 gallons and a few F with 54.8 but these are rare.  

The 54.8 gallon bladder installation eats up 29.8 pounds of useful load.  Don't know about the 64 gallon.

Actually in a J three gets you roughly 55 gls. to get the full capacity back, you need four bladders.

Apparently the original J kits were only three bladders per side, the four per side is a relatively new thing, the fourth bladder can be added to a existing system that only has three, but I don’t know the cost. I believe my three per side gets me 54.8 gl total on my J

 

 

Edited March 20, 2021 by A64Pilot

[BDPetersen]

3 bladders each wing 54 gallon C.

[David Lloyd]

1 hour ago, BDPetersen said:

3 bladders each wing 54 gallon C.

Yep, now that I think about it, the drawings do show 3 bladders per wing for my C. A fourth (not 3rd) bladder would bump it up to 64 gallons.  Sorry for the error.

[A64Pilot]

On 3/20/2021 at 7:32 PM, David Lloyd said:

Yep, now that I think about it, the drawings do show 3 bladders per wing for my C. A fourth (not 3rd) bladder would bump it up to 64 gallons.  Sorry for the error.

I believe that 4th bladder at least for a J is available, I don’t know about other models. I’ll just live with the lower capacity due to cost myself.

[J0nathan225]

I talked with Griggs last month 64 gallon (4 bladders a side) is available for C-J (I'm assuming somewhat, but it was confirmed available for my E).  I believe I was quoted ~10500 w/ install for 54 and ~14500 w/ install for 64 gallon.  They will ship to your mechanic for install if you wish. FWIW no state tax on transaction.

 

http://griggsaircraft.com/fabrication/mooney_bladders

[steingar]

If all goes well I'll be adding the 64 gallon option to mine.  you can never have enough fuel.  That, and we're going to need 64 gallons to fly to Europe...

[Marauder]

12 hours ago, bluehighwayflyer said:

My dad installed 54 gallon bladders in my C back in 1994 and the 10 gallon add-on in 2005 not long after it became available.  I also installed 64 gallon bladders in my previous J back around 2008.  I can’t recommend them highly enough.  Particularly the 64 gallon option for the short bodies, which often can’t take full advantage of their useful loads anyway due to limited rear seat leg room.  

Thanks for the vote of confidence for the 64 gallon tanks. I am still flying with my 54.8 gallon (really is only 52 gallons) since I had them installed in 1992. With post-apocalypse flying a real possibility later this year, I am thinking having the extra gallons on board would be beneficial. 

12 hours ago, J0nathan225 said:

I talked with Griggs last month 64 gallon (4 bladders a side) is available for C-J (I'm assuming somewhat, but it was confirmed available for my E).  I believe I was quoted ~10500 w/ install for 54 and ~14500 w/ install for 64 gallon.  They will ship to your mechanic for install if you wish. FWIW no state tax on transaction.

 

http://griggsaircraft.com/fabrication/mooney_bladders

My, my, prices have gone up. My 54.8 gallon system was $4,800 in 1992. Looks like a 4% per year price increase. I can't say enough good things about the folks at Grigg's. I installed their new flush style caps and had issues with one not sealing. They sent me a reseal kit no questions asked.

Edited March 23, 2021 by Marauder

[EricJ]

7 hours ago, steingar said:

you can never have enough fuel.  

Unless you're crashing or on fire. 

 

[jaylw314]

3 hours ago, EricJ said:

Unless you're crashing or on fire. 

 

Well, THERE's the cheerful thought for today! 

[carusoam]

It’s a classic reference...  

Perfectly matching... to the post apocalyptic reference...

If 60 is good... then 130 must be better...   go long body!  Really good for those impromptu flights to Europe...

Best regards,

-a-

[Cloudmirth]

Just replaced the fuel level sender in the right tank (O&N bladders).  Tested sender before installing and it moved the gauge perfectly empty to full.  Once installed, as the tank was filled gauge moved from empty to half and then stopped.  Has anyone had an issue with a sender hanging up in the bladder and, if so, what can be done about it.

[carusoam]

Mirth,

You need to check why it is doing that...

If your bladder is collapsing on it... that is an install issue...

If the the bolts holding the fuel level sensor have been overtorqued... it may limit how the fuel level sensor is working...

See if you can stick your hand in there and verify the operation of the fuel level sensor now that it has gone that one step further...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Marauder]

Just replaced the fuel level sender in the right tank (O&N bladders).  Tested sender before installing and it moved the gauge perfectly empty to full.  Once installed, as the tank was filled gauge moved from empty to half and then stopped.  Has anyone had an issue with a sender hanging up in the bladder and, if so, what can be done about it.

You didn’t say what model Mooney you are flying. I have seen my old senders hang up in my F model with O&N bladders. It had nothing to do with the bladders, just the sender hanging.

Is the sender a rebuilt or new sender? Also, did you get the orientation right when you reinstalled it? When I replaced my senders with CiES senders, I had to invert 2 of them to clear the bladder side walls (their label was on upside down).


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