Time to reseal the tanks

[wombat]

I got my plane back from Edison at Wet Wingologists early last month after a full reseal of the mains and the monroy long-range tanks.  He was on time and on budget.  The tanks don't leak. 

Edison was easy to communicate with over text and phone although I am the one that initiated all requests for updates.   

My paint is not great to begin with (See attached picture) so I can't tell if the paint is 'damaged' at all.    There is an area over one tank that has a different sheen now than it did before, but I'm expecting to repaint in the next 3 to 5 years anyway so I don't care and he knew that before starting.

I have encountered one problem that seems like it's a problem caused by Edison's work:    Both fuel gauges are reading as if one of the floats in them is always at full travel down (empty) so they now read < 20 gallons even when they have 52.5 gallons in them.   I don't know for sure if the problem is due to the floats being stuck down or an electrical problem; I am trying to get a borescope into the tank at the same time as a tool to try to move the float to see if that changes the indicated fuel.   But getting through those flappers and then poking through rib holes is challenging and I don't have much time to devote to it.     I'm pretty sure this is a result of Wet Wingologists's work but Edison has been great about providing advice and tips on how I can diagnose the problem and has said he'd be willing to work on it as necessary to fix it at no extra charge if I bring it back to him.     That is kind of difficult for me since I'm 2,288 NM away from him, but this is something I knew could happen before I took the plane in.

 

I decided to do a full reseal since I had at least 7 identified separate leaks and there could have been several more leaking into the interior of the wings.   My tanks had the original seals from manufacture in 1984 and the long-range tank addition in (I think) 1990.    If the new reseal lasts this long it'll probably outlast my capability to fly this airplane; I'll be shocked if I am still flying it in 32 more years.  If I fly at all in my 80's it'll probably be something slow and simple.  Like a C or a J.    

[Pinecone]

If one sender seems to be showing empty, it may be a grounding issue.

If the guage reads some middle level until you burn down to around that level, then reads normally, it could be that the inboard sender goes to ground instead of to the outboard one.   The inboard sender has insulating washers to isolate it from ground.

You could check this with full tanks to check the resistance on the outboard sender.  IIRC, at full, it should read 30 ohms.

[wombat]

@Pinecone Do you know where to access the wires for the outboard sensor?   I'd love to do that but I don't know how to get to them.

I'm like 90% convinced it's an electrical problem and not a sticking float problem, but I don't want to try to tear up the interior to get at the wiring on the inboard ones and took off a couple of the panels under the wing but didn't see anything that looked like the back side of a fuel sender.

[Shadrach]

1 minute ago, wombat said:

@Pinecone Do you know where to access the wires for the outboard sensor?   I'd love to do that but I don't know how to get to them.

I'm like 90% convinced it's an electrical problem and not a sticking float problem, but I don't want to try to tear up the interior to get at the wiring on the inboard ones and took off a couple of the panels under the wing but didn't see anything that looked like the back side of a fuel sender.

The sending units are at the outermost (accessed through wing) and innermost (accessed from cabin) ribs. It is very likely a minor issue. IIRC, neglecting to connect the leads to an outer sending unit will cause the symptoms you describe. 

[wombat]

@ShadrachShould I just start pulling lower access panels until I find the right one?  Is it immediately obvious when I pull the nearest panel? Can you identify which one it would be from this diagram?  Sorry to be so needy. 

 

I'm kind of paranoid about accidentally pulling one of the ones from the fuel tank.

 

Twice shortly after landing I noticed the fuel gauges reading "full" for a little bit.  On taxi-back to the start of the runway I looked over and they were at 30+ gallons, then I look back a few seconds later and they were low again.   This leads me to believe that there is a disconnected or poorly connected wire somewhere.

[Shadrach]

2 hours ago, wombat said:

@ShadrachShould I just start pulling lower access panels until I find the right one?  Is it immediately obvious when I pull the nearest panel? Can you identify which one it would be from this diagram?  Sorry to be so needy. 

 

I'm kind of paranoid about accidentally pulling one of the ones from the fuel tank.

 

Twice shortly after landing I noticed the fuel gauges reading "full" for a little bit.  On taxi-back to the start of the runway I looked over and they were at 30+ gallons, then I look back a few seconds later and they were low again.   This leads me to believe that there is a disconnected or poorly connected wire somewhere.

Yea, disturbing a fuel tank screw would be a bad deal. I am not familiar with the configuration of your tanks, so not comfortable advising. You should be able to discern which panels from the IPC. Typically fuel tank access panels are made from two layers of sheet metal so there is a rivet line around the outside of access panel inboard of the screws on the wing. In most cases, the sealant is visible where the panel mates to the wing. On my 60s era bird the dry wing inspection covers are usually a single piece of joggled sheet metal with a hole in the center.  A joggle is a step that is bent into the panel so it is flush when mounted.  Again, I am not advising you to open any panels without someone with experience to help.

[Mcstealth]

Not to completely change the subject, bladders can or cannot be removed from the plane, and go back to sealant? 

[Shadrach]

22 minutes ago, Mcstealth said:

Not to completely change the subject, bladders can or cannot be removed from the plane, and go back to sealant? 

It could be done. How difficult it would be I cant say. The fuel cap and filler neck are changed when bladders are installed, I am not sure is any metal is cut in the process.

[kris_adams]

at risk of starting the debate...can't imagine why one would ever want to...I sure wouldn't go back...never

[wombat]

I got into the wing tank with a borescope and a thin flexible metal rod (filed smooth and round at the end) this morning and was able to lift the outboard sender about halfway up; the fuel gauge did not change after 30+ seconds.   I'm even more confident that it's a wiring problem.

Edited August 11, 2023 by wombat

[Shadrach]

2 hours ago, kris_adams said:

at risk of starting the debate...can't imagine why one would ever want to...I sure wouldn't go back...never

No need to debate.  I can't imagine wanting bladders. I have many reasons for feeing that way but opinions are like...

[kris_adams]

2 minutes ago, Shadrach said:

No need to debate.  I can't imagine wanting bladders. I have many reasons for feeing that way but opinions are like...

here we go lol...

[Fly Boomer]

9 hours ago, wombat said:

Should I just start pulling lower access panels until I find the right one?  Is it immediately obvious when I pull the nearest panel? Can you identify which one it would be from this diagram?  Sorry to be so needy. 

 

I'm kind of paranoid about accidentally pulling one of the ones from the fuel tank.

 

Twice shortly after landing I noticed the fuel gauges reading "full" for a little bit.  On taxi-back to the start of the runway I looked over and they were at 30+ gallons, then I look back a few seconds later and they were low again.   This leads me to believe that there is a disconnected or poorly connected wire somewhere.

See if this diagram from an M20K helps:

 

[kortopates]

Really don’t need the diagram. just get under the wing and the inspection covers that are sealed are quite obvious compared to the ones that are not. The outboard sender is at the outer side of the main tank, just realize the extended tank is further out from that but also further back or aft in the wing, and of course without a sender.
Even if you end up removing a couple wrong panels you can’t hurt anything. Unlike a dry inspection panel it’s very very difficult to remove a sealed wet panel.


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[Shadrach]

5 hours ago, kortopates said:

Really don’t need the diagram. just get under the wing and the inspection covers that are sealed are quite obvious compared to the ones that are not. The outboard sender is at the outer side of the main tank, just realize the extended tank is further out from that but also further back or aft in the wing, and of course without a sender.
Even if you end up removing a couple wrong panels you can’t hurt anything. Unlike a dry inspection panel it’s very very difficult to remove a sealed wet panel.


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I agree that they ar obvious. However, if you have to ask, than maybe it’s better that you have help. I’ve seen smart people do boneheaded things.

[N201MKTurbo]

About 30 years ago, I was working on my annual. A friend was helping. I showed him which panels to take off under the wing. A few minutes later he says “hay Rich, one of these panels is stuck” I look down there and NOOOOOO!!! He had all the screws out and was pushing on one of the tank panels. I yelled “STOP”. 
 

I carefully put all the screws back in and miraculously, it didn’t even seep a little bit. 

[wombat]

So I got a borescope into the left tank using a metal since the borescope neck was floppy.    Then I could see the outboard fuel sender, and was able to take a second rod and go lift it up.  It didn't seem to be stuck down at all, but hard to tell since I'm working past the fuel filler flap as well as through a hole in the rib.    I held it up for 30+ seconds with the engine monitor on and the fuel gauges still read 0.    

But then when I went and filled the tank up the fuel gauge was reading 'normal' again,  reading roughly the capacity of the main tank only.     The right tank is still reading 15 gallons maximum, but once I get it emptied out I'll go and poke the floats in there and I expect it'll work like normal again too.

 

Funny thing, I put 27 gallons into the left tank  which was completely dry because needed an extra 150# of useful load, so I was leaving 25 gallons empty and while at the very first it showed about 25 gallons, during the flight I didn't burn any from that tank and an hour later it was showing about 19 gallons left.  I guess the fuel was flowing into the long-range tank.   

[kortopates]

 
Funny thing, I put 27 gallons into the left tank  which was completely dry because needed an extra 150# of useful load, so I was leaving 25 gallons empty and while at the very first it showed about 25 gallons, during the flight I didn't burn any from that tank and an hour later it was showing about 19 gallons left.  I guess the fuel was flowing into the long-range tank.   

The extended tanks don’t empty until the main tanks are down to half full or ~18 gal. Therefor when ever you add fuel to the mains and bring a tank above half way, some of the fuel will run out into the extended tank. It takes some time for them to balance out.


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[wombat]

3 hours ago, kortopates said:

 

The extended tanks don’t empty until the main tanks are down to half full or ~18 gal. Therefor when ever you add fuel to the mains and bring a tank above half way, some of the fuel will run out into the extended tank. It takes some time for them to balance out.


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Yeah, I'm aware of how this all works.    Now it's just a matter of getting the fuel gauges calibrated.   I think I'm going to buy myself 11 5 gallon buckets, a 1 gallon jug, and a funnel.   Then I can add one gallon at a time, wait for things to level, measure with a stick and measure resistance, then put in the calibration points I want.

[Pinecone]

I wrote any article for Mooney Flyer on calibrating dipsticks for my 252 with Monroy tanks.

I used 5x 5 gallons jug.   I ran one tank to engine sputtering.

I filled the 5 jugs, then poured one into the tank, as I knew it would not be measurable.  Then I poured 1/2 of a jug into the now empty one, so I added that and have 7.5 gallons.  Then the other left over 1/2 jug for 10 gallons.  Repeat.

In my plane, I was able to put 55 gallons in that tank, versus the official 52.  And may have been able to squeeze in maybe 1 more.

After each addition, I waited 5 minutes for the fuel to settle between the two tanks.

I got my jugs from Amazon, I got the Jeg's ones in white/clear.  And I got one spout for pouring.

[wombat]

I'll probably do something similar, but also use the MVP-50's calibration process.  And a bunch of 5 gallons buckets are way cheaper, plus I can re-use them for other things later.      CB Club for the win.

 

[MikeOH]

Why does pouring multiple 5 gallon plastic buckets of gasoline make me nervous? Just make sure you use a closed hangar while smoking

[OR75]

honestly, if someone has to ask on this forum how to differentiate a fuel panel from an inspection panel, probably should get help from a shop.

avgas is very very flammable 

[wombat]

I deal with and have dealt with a lot more dangerous stuff.   Avgas is not scary.

While some of the panels are obvious which ones they are before looking too close, but some are not.

[Greg Ellis]

11 hours ago, MikeOH said:

Why does pouring multiple 5 gallon plastic buckets of gasoline make me nervous? Just make sure you use a closed hangar while smoking

And, by all means, please don't ground anything.