Fuel Tank Leaks and sealing....

[wombat]

Sooo....  I'm trying to buy an airplane.   Most things on the plane are good, but the tanks are leaking pretty badly and I'm trying to negotiate a price that takes this into account.    Pictures of the fuel leaks can be found here: https://photos.app.goo.gl/ecnYFM7PP7y2Z7mr9 (Includes a page of the service manual talking about seeps and leaks)

Every tank is leaking at least somewhere.   There are 6 where the fuel is running back on the wing, and two of them are leaking into the confined areas of the wing.   According to the service manual, these should be fixed before the next flight.

Houston Tank Specialists and Weep-No-More are both booked out to the middle of next year although wet-wing-ologists can get me in this year. I don't think this plane should fly until these are fixed, but maybe I am reading too much into the service manual's text.   So I'm looking at several thousand dollars to patch now if I want to fly it now, and then $19,000+ (estimate from Houston Tank Specialists) to fully reseal all four tanks in another year and a half, so my total outlay will probably be $25k.

 

What other options do I have?  Anyone else doing full tank reseals?  I don't want to have a struggle with the tanks like @Barzook is having and I don't want to fly with avgas build-up in the wings, or paying "the angel's share" on my fuel because 10% of it drips out.    Am I just being too worried and the leaks in these tanks are just fine to fly with in the meantime?  There is enough fuel inside the wing cavities that I'm sure there ends up being a stoichiometric ratio of fuel and oxygen in that cavity some of the time, which feels pretty dangerous to me.  There are wires that run through there too and a tiny spark could literally blow my wing off.

 

Too bad wetwingologists are in the absolute farthest corner of the country from where I live. 

Edited April 12, 2023 by wombat

[Fly Boomer]

2 hours ago, wombat said:

Too bad wetwingologists are in the absolute farthest corner of the country from where I live.

I'm not sure if it adds anything to the equation, but those brown to black stains have been accumulating for a long time.  I only saw blue on one of your pictures.  Actually, the extent and age of the fuel staining would encourage me to look hard for other things that have not been cared for.

[wombat]

In person it's clear that many of them have fresh fuel flowing out of them as well. Not all that much, but enough that when flying the wind makes a trail of fresh blue fuel.   Kind of hard to see in the pictures though.

 

Yes, these have been accumulating for years.  The plane has not been washed since at least 2020, and when looking at the condition of a new part that was installed in 2020, the other parts were very dirty before then so I would guess the plane hasn't been washed since 2015 or before.

LASAR recommended that if I buy this plane, I should NOT wash it until I get the tanks sealed, since the dried fuel dye is probably keeping the leaks from being a lot worse than they are right now.

Thanks for the advice on looking for other things, @Fly Boomer.    I think my pre-buy was pretty thorough and while the fuel leaks are troubling and there are a few other things that I'd like to fix (Engine monitor needs IRAN and the plane needs paint) I think that other than the tanks, the overall condition is acceptable considering the price.

 

[GeeBee]

I just did a complete reseal with Wet Wingologists in FXE. Very happy, the work looks good. All he does is Mooney's. No other types. He knows his business.

Price all in after reseal, new drains and drain receptacles as well as re-filling the tanks was 15,100.

[wombat]

Thanks for the report,  @GeeBee I take it you do not have the long range monroy tanks,  at that price?  Either that or the ovation's fuel tanks are different enough from the J&K tanks...

 

Did you have to worry about compliance with AD85-24-03 and SBM20-230A?  In the thread about a J that got resealed elsewhere there seems to be some problems that compliance with these should have resolved.

https://wwwapps.tc.gc.ca/Saf-Sec-Sur/2/AwD-CN/documents/US85-24-03.htm

https://www.mooney.com/wp-content/uploads/2020/12/SBM20-230A.pdf

Edited April 13, 2023 by wombat

[GeeBee]

Not specifically because the work is done in conformance with the M20R MM which has those issues contained within it.

As I said, they only do Mooneys there and he had a J and a K as well as M and R and S models. Edison knows his stuff about all of them.

I guess I got lucky because I called him and he said if I could be there in the next 3 days he could get right on it and promised me a 3 week completion date. He delivered on time, and on budget.

[carusoam]

The Service manual has interesting details about fuel leaks..

Acceptable vs. get fixed soon Vs. Fix now….

The M20K has the most complex version of a Mooney fuel tanks…

The short and mid bodies are very similar…in design

The long bodies have longer fuel tanks… and really simplified things…   Max capacity is 130gal.

PP thoughts only,

-a-

[carusoam]

Discussing what we see here…

It looks like fuel is leaking past many rivets in the bottom of the tank…

When you see fuel stains coming out the wing drain… that indicates there is an internal fuel leak as well

In another pic there was huge globs of fuel leaking around the sump drains…  this is an easy fix that takes 10 minutes…

Lots of paint missing…  looks like it doesn’t want to stick to the aluminum…

Plan A: Seal the tanks prior to painting the plane… solvents are bad for both finished paint and finished sealants….

 

 

fuel sump drains are similar to a big bolt… pretty easy to unscrew, clean and replace, or just replace…

With so much missing paint…keep your eyes open for surface corrosion… plan on cleaning and painting to avoid surface corrosion starting and spreading….

PP thoughts only, not a mechanic…

Best regards,

-a-

[carusoam]

Is this plane otherwise special and worth bringing up to speed?

a few MSers have taken on the task to reseal their own tanks…

It takes a ton of hours, working with solvents, and is messy….

Raptor/Alex did his a few years back and posted many pics during the process….

Best regards,

-a-

[carusoam]

I don’t think the fuel die and lead component acts as any kind of impromptu sealer… or else we would never see rivets leaking…

It would be similar to leaving sugar on your cracked soda glass hoping to keep your Coke from escaping…

sure… the soluble material may slow things down a bit…. But not enough to make a difference.

 

That much fuel leaking outside is a bit disheartening…

The more scary leaks occur in the cabin…

Lift the carpet in the back seat… expect to see the carpet soaked in blue stains…

There are at least two sources per side for common leaks… the fuel level seal and fuel line connector… they last about 40yrs before deteriorating and leaking…

These bits are low cost easy fixes…

Slightly more challenging than the fuel drain…

PP thoughts only, not a mechanic…

-a-

[wombat]

@carusoam Yes, it is leaking from the screws in the bottom access panels, the access panel seals, the sump drains, and also as at least two places internal to the wings.   Anything less than a full strip and reseal of the tanks is going to be nearly as expensive because so much has to be patched and getting the patches all actually sealed will probably take multiple tries.  While I am quite often willing to perform extensive labor for my projects, this is one I am not comfortable doing.  I've talked to 5 shops including the three biggest names in tank sealing (Houston Tank Specialists, Wet Wing-ologists, and Weep-no-more) for their evaluation, quotes, and timeline.  They've all said that the condition as pictured (or in the case where I simply described it) really needs a full strip and seal, so that's what I'm expecting to do.  There is no fuel smell in the cabin at all, but that basically doesn't matter because the very first thing this plane needs is a full strip and reseal anyway.

As far as being a 'special' plane...  Nope.  I don't own it, it's not the slightest bit special.   It is one of the very few aircraft with the engine, avionics, and ice capabilities I want that are in my price range.  I am negotiating with the broker and sellers on the cost of getting the plane airworthy again. But there are others that are nearly as good and if I add the price of the sealing work and the price of even half of the paint job that this plane desperately needs to the cost of the plane as is...    I'll find another plane and watch this one sit on the market for a year.

The dye does not act as a sealer, but it does slow down the leak flow rate significantly.  You can plug your bottle of coke with a couple of sugar cubes. and while the coke will still escape, it won't pour out, it'll seep out.

 

@GeeBee Thanks for the info. The last time I looked at Mooneys my budget was smaller and mid and long bodies were out of my price range.

[carusoam]

You mentioned four fuel tanks… sounds very M20K ish…?

Has the engine been flown much? Or time just stopped one day around Covid?

Access panel screws are an easy reseal fix…

the leaking rivets indicate the sealant is just largely broken down inside the tank…

If you look inside the tanks can you see sealant flaking off or creating what looks like worms?

Certain years of Mooneys got terrible sealant… big improvements came in the 80s and 90s…

 

Just use caution with the leaks… dry air and static sparks can be really unfriendly… basic fuel safety.

 

The good news… A modern reseal will last decades… if not left out in the Arizona sun with empty tanks… 

 

Did you mention a TKS system…?   They like to be run often. Sitting idle has its own challenges.  Another sugar like situation…

The PPI should cover demonstrating all systems working… so you know what to expect if you decide to move on to the purchase step…

Best regards,

-a-

 

[wombat]

Yes,  this is a K.   A rocket, specifically. Yes, it has TKS. Yes, I flew in it. More briefly than I'd like, but better than nothing.  Between the flight and the prebuy we tested just about everything.   Didn't test ILS or VOR receiver,  but it's got a 750 and there is a clear path to fixing those if there is a problem.

The engine has not been sitting for very long.  The TKS, maybe.  But I tested it and it works,  so I'll take the risk.

 

If the sellers and I can come to an agreement on what to do about the cost of these tanks, I'll be transferring the money into the escrow account this week.

[carusoam]

How did you like the climb rate?

Best regards,

-a-

[wombat]

I'm satisfied with the climb performance.   It is appropriate for where I live (On the East edge of the Cascade mountain range)

[carusoam]

Very appropriate for the east edge of Lake Erie as well…

Icing can be a hassle East of any large body of water…

Adding oragraphic lift to the equation makes the Rocket a nice tool to have…

Best regards,

-a-

[1980Mooney]

On 4/12/2023 at 2:37 PM, wombat said:

So I'm looking at several thousand dollars to patch now if I want to fly it now, and then $19,000+ (estimate from Houston Tank Specialists) to fully reseal all four tanks in another year and a half, so my total outlay will probably be $25k.

"$19,000+ ... total outlay will probably be $25k"  Unbelievable.  What an escalating ripoff to seal Mooney tanks.  I wonder how many Mooney owners realistically budget for that or honestly factor it into the true cost of "thrifty Mooney" ownership.

And given the sad state of the paint in the pics you posted, I assume that you have seen the recent MS topics on repainting costing about $30K

Last, pay close attention to the condition of engine mounting frame on the Rocket - especially close to hot spots.  Rocket Engineering uses very thin wall tubulars with 3 different wall thicknesses getting progressively thinner.  The slightest corrosion on the engine mounting frame can lead to airworthiness issues.  Rocket Engineering still supports the Rocket and Missile.  I had my Missile engine frame repaired by Rocket about 1 1/2 year ago (rewelded, oil filled tubulars, powder coated).  The labor involved to remove and reinstall the engine mount really drives the cost up.  There are some topics on MS regarding this - one owner welded the frame in place.  I see you are in Rocket's backyard not far from Spokane which is good.

 

Edited April 14, 2023 by 1980Mooney

[wombat]

Latest developments....    The seller and I have negotiated a price that we are both satisfied with considering the condition of the aircraft as documented in the prebuy.

I'm on the schedule with Edison at Wet Wingologists this year and will be only ferrying the plane down to him and not flying it in the meantime.

Yes, I'm aware of the cost of a paint job and expect to have this plane repainted probably in 2026 to 2028.  I have factored this into my estimated cost as well.  Fortunately I live in a very dry environment now and also have a hangar so I don't expect there to be a problem with corrosion getting worse.  Not that there is significant corrosion now.  I looked over every inch of the plane, as did the prebuy shop.  

Yes, we looked closely at the mounting for the engine and there is a tiny bit of work to be done there.   As you say, some of the spots are hot.   

 

But when looking at the overall condition of the aircraft, I think it'll be worth it once I've put another $50,000 into the plane.   Which is funny because neither of my previous two planes have been worth $50,000 

 

And as far as the $19,000+ for tank sealing....  Well, they have a product that is in demand and they are able to charge that much and still have customers.  I don't want to pay it, but I want their services.   So good on them for developing a product that they can market and continue their business.   If I thought they were making crazy money off of unsuspecting Mooney owners, I could start my own business doing the same.   But I don't. As long as Edison delivers the product he promises (well sealed tanks that will last a long time)  at the price he promised, good on him!

[Fly Boomer]

59 minutes ago, 1980Mooney said:

Last, pay close attention to the condition of engine mounting frame on the Rocket - especially close to hot spots.

^^^THIS^^^

You may need a mirror on a stick to check the backside of some of the engine mount tubes, especially near the turbo.

[GeeBee]

The leak around the drain will require drilling out the two rivets holding the receptacle, then replacing the receptacle and the drain. It is difficult to re-use the old receptacle as it takes a "stretch" when the drain is torqued down. Best to replace it.

[wombat]

I'm trusting that Edison at Wet Wingologists knows what to do. 

[ArtVandelay]

"$19,000+ ... total outlay will probably be $25k"  Unbelievable.  What an escalating ripoff to seal Mooney tanks.  I wonder how many Mooney owners realistically budget for that or honestly factor it into the true cost of "thrifty Mooney" ownership.
And given the sad state of the paint in the pics you posted, I assume that you have seen the recent MS topics on repainting costing about $30K

Wow, 10 years ago paint jobs were $12k and reseal jobs were $8k.

I’m confused, what Mooneys have 4 tanks?

[wombat]

@ArtVandelayIt's got the monroy long range tanks.

 

And yeah, inflation is a pain.

[1980Mooney]

2 hours ago, ArtVandelay said:

Wow, 10 years ago paint jobs were $12k and reseal jobs were $8k.

I’m confused, what Mooneys have 4 tanks?

He has Monroy Long Range Tanks.  The "long range" tank is a separate tank that gravity drains into the main tank.  If you look at the parts list you will see that they use a straight 3/8 inch union fitting, AN832-6D, and a a 3/8 inch elbow, AN833-6D, to connect the 2 tanks and allow fuel to gravity flow between tanks depending on level in each tank as it is filled or the main tank is consumed.  Since the connection between tanks is only 3/8 inch ID, that is why the tanks do not immediately equalize when fueling either the main tank or the long range tank fuller than the other..

https://skygeek.com/mil-standard-an832-6d-union-flared-tube.html

https://www.aircraftspruce.com/catalog/hapages/an833.php

Look at the 3rd pic in this topic - the OP included a copy of the parts list for an M20K installation.

 

Edited April 14, 2023 by 1980Mooney

[Pinecone]

4 hours ago, 1980Mooney said:

He has Monroy Long Range Tanks.  The "long range" tank is a separate tank that gravity drains into the main tank.  If you look at the parts list you will see that they use a straight 3/8 inch union fitting, AN832-6D, and a a 3/8 inch elbow, AN833-6D, to connect the 2 tanks and allow fuel to gravity flow between tanks depending on level in each tank as it is filled or the main tank is consumed.  Since the connection between tanks is only 3/8 inch ID, that is why the tanks do not immediately equalize when fueling either the main tank or the long range tank fuller than the other..

It sounds like a good upgrade would be a second fitting to flow fuel.  It does take a good bit of time for them to equalize.  It makes it hard to fully fuel the aircraft.