Fuel Tanks?

[highplains]

Mooney Pilots,

First of all, thank you all for sharing.  I think I have read almost every post no this forum.  Excellent education.  I found Mr. Perry's write up of particular interest.

 So here is the deal....I hope to soon make the transition from brand "C" and think I have found the M20E that could be "The One".  It meets almost all of my requirements.  This said, I am concerned about the fuel tanks.  The last time the fuel tanks were sealed was when it left the factory.  Evidently, they do not leak now, and I usually adhere to the old maxim of "If it is not broken, do not fix it".  Now, maybe they last another 5 years, maybe 10, maybe six months.  I will assume that sometime within my tenancy, they will need to be repaired.  So, the question is, how do I value this condition with regard to the overall aircraft?  Also, I would appreciate it if members of this august group could provide guidance as to the costs associated with the two options of strip/reseal and bladder installation.  If anyone could quote semi-recent pricing on the two that would be great.  I would even like to hear debate on the merits of the two as well.  

Cheers,

Jason

[N601RX]

From O&N bladders web page.  The prices do not include labor.  Most of the shops they recommend charge around $85 hr.

54.8 Gallon Kit (Six Bladders)	40	$5,850.00
64 Gallon Kit (Eight Bladders)	50	$7,750.00
10-Gallon Add-On Kit (Two Bladders)	15	$2,450.00

 

I think a good reseal is around $8,000. 

[takair]

It's amazing they have never been resealed.  Be sure to inspect with tanks topped off.  I suppose you could ask for some deduction.  I had bladders put in by O&N about 7 years ago.  I really like the peace of mind.  On the E model they actually add a little capacity.  The only thing I don't like now is the wieght.  As I recall, it is a little over 30 lbs to the empty weight.  It was not a big deal back then, but my kids are getting bigger and I could really use that 30lbs now.  Time to get a bigger plane.  In the end, I would do the bladders again....just keep the 30 lbs in mind.  Also, check the accuracy of your fuel guages.  Whether you reseal or do bladders, concider having your senders overhauled at that time.  Also, be sure to have the guages checked for calibration after doing the bladders.  It took me a while to get them to read right.  Would have been easier at the time. 

[richardheitzman]

You can contact Wilmar to see what the cost is on the strip and reseal. They have the process that chemically strips the tanks and then they go in and reseal. Good warranty and lots of happy customers.

[DaV8or]

Quote: takair

It's amazing they have never been resealed.

[AustinChurch]

Don Maxwell in Longview, TX is now offering the same tank strip/reseal process as Wilmar so you might want to check with them as well.

http://www.donmaxwell.com/

[acronut]

O&N can install their bladders cheaper than you can have it done anywhere else.  Give them a call and get a current quote.  I got one not long ago but I can't find the #'s.  I like the idea of having the bladders so I don't have to sweat going into a grass strip once in a while or a hard landing possibly cracking a sealed tank.  From what I've read it adds 35lbs to the plane.

Kendal

[KSMooniac]

There has been quite a lot of debate on the merits of bladders vs. reseal on this forum before, so I'd suggest searching a bit more instead of starting anew here.  Regarding a deduction on asking price for not having a reseal...that is a tough call.  If it were me, I'd use Jimmy Garrison's most recent spreadsheet evaluator for the Pre-J planes and see how that compares to the asking price as a first step.  You'll see lots of planes advertised with a Willmar reseal (or similar) so there is definitely some value to having it done.  I'd estimate that the value is about half the cost of the task (similar to avionics or cosmetic upgrades) so figure a plane would be worth ~$4k more with than without.  However, one can't really deduct from a sales price if it hasn't been done and the tanks aren't leaking either!  If the plane is otherwise perfect, then I would still pursue it seriously and just keep in mind that you might get to do the tanks at any time...much like flying past TBO.  Finding everything you want in a used airplane will not be possible, so prioritize what is important to you and get the one that has as much as possible.  Old, non-leaky tanks wouldn't bother me at all if the plane was otherwise nice with a modern panel, good history, nice cosmetics, etc.  You could, for example, spend a lot more adding an autopilot than resealing the tanks, so I'd rather have the autopilot and fly it while preparing for tank work in the future.

I went for the reseal at Willmar in 2008 and was extremely pleased.  Willmar has since sold, and the guy that specialized in the tank repairs recently went out on his own now and is doing business under a different name/shop but I don't recall what it is called.  Should be easy to find, though.  Don Maxwell's shop would probably do an equally nice job and is a good alternative.  I place a high value on useful load and didn't want to add to my empty weight with bladders, or pay more than the reseal cost.  Do your research and you can make an educated choice...but in the mean time just fly it! 

[Piloto]

You will notice that none of the new popular planes use bladders anymore. Aside for the bladder payload penalty there are other issues to consider. With a single can of sealant you can fix the tanks of a Mooney all the way up to a B777. MROs no longer have to stock different bladders like for the B707 but just a few cans of sealant. With bladders you could be in trouble if an specific bladder replacement is not available. With integral tanks you don't need to worry about finding material to fix either side. If not inspected on a routine basis bladders can cause corrosion to the main spar by trapping moisture between the bladder material and the structure (an annoying problem on the B707). Water entrapment created by bladder wrinkles is another problem found on the early C172. Fixing a bladder leak takes a longer time than an integral tank. Not to mention if you need to order a new bladder. Mooneys with bladders are not compatible with long range tanks option.

José

 

  

[highplains]

Guys,

Thanks for offering your opinions regarding my question.  This is exactly what I was seeking when I posted the question.  I'm inclined to discount some for the fact it has been such a long time.  Much like an overhaul that was done long ago.  Even if the hours since overhaul do not indicate the need, we all know what time does to an engine.  

While not new to aviation, nor to buying aircraft, I am new to seeking a Mooney.  The tank issue seems to be more important than in other types.  The C-182 I am in now has wet wings and I don't see the concern with those as with Mooney's.  In any case, thanks for the replies.  

Tailwinds, always....

JV

 

[flyby201]

If you have a good relationship with an A&P and lots of time on your hands you can do the strip and reseal with the same chemicals Willmair uses (under the supervision of your A&P, of course).  The stripper is called Poly-Gone 300 AG.  It comes in a liquid and a gel.  I think the Mooney shops use the liquid as they have a contraption that sprays and re-circulates the chemical in the tank.  The gel is applied with a brush and stays in place.  I did one tank a few years ago with this process and it was a LOT of work (100 to 120 hours), but it was not something which one needs a lot of training to do.  I called the striping process something a trained monkey could do.  My tank had been patched and re-patched several times by previous owners and there were places where I counted 5 layers of sealant.  If you just have the original sealant in yours it would probably be much less work.  It is a lot of chemical application and scraping with non-metalic scrapers.  I found a strip of formica sharpened on one end with a die grinder worked best as a scraper.  You have to remove ALL the sealant down to the bare metal, in all the cracks and crevaces.  Once it is all removed, your A&P can reapply new sealant as described in the Mooney Service Manual.  At the time, I had a work schedule that gave me plenty of time to work on it and I figure it cost about $1200 to seal that one tank.  If you take your time and follow directions the sealing job will be as good as anyone else can do.  I've had no leaks in that tank.

Poly-Gone is made by a company called RPM Technology and here is a link to their website:  http://www.rpm-technology.com/default.htm.  The are good people and will answer your questions if you give them a phone call.  The product can be ordered from Aircraft Spruce, API, or Aviall.  The sealants are made by FlameMaster, Chem-Seal and maybe others.  I used the Chem-Seal products and they were also very helpful.

Would I do it again to save that much money?  You bet.  The bulk of the work is the striping process and I figure my spare time is free.  $2400 to do both tanks vs. $8000 from the big guys.  That's a $5,600 savings which I have to spend on new avionics or some other upgrade.

[Rage]

JV,

I would certainly consider the reseal when pricing the aircraft you are going to purchase.  I bought a 68 20F last February and during the pre-purchase inspection that was one of the things I specifically wanted them to check.  Unfortunately that was either ignored or not noticed (it was done at a MSC in NY) and shortly after getting the plane out here to Utah we notice some weeping and blue stains inside along the airframe tubing behind the interior side panel covering.  10 months later the tanks are now "leaking" and we are going to have to get them resealed in the next couple of weeks.  The current quote I have is $8300 + a potential extra $5-$1000 for replacing some screws on the access panels.  This quote was from an MSC in OR.  In retrospect, knowing the tanks had not been resealed since it left the factory, I wish I would have considered that in the price I paid.  An unexpected $8k+ price hurts after you just bought a plane and made all of the little mods you wanted to make it "your" plane.  

 

Blue Skies,

Rage

[tony]

Rage, does you tank still leak if it’s half full?  Before you dive into a reseal, you should check the gasket where the sending unit penetrates the fuselage and snug up the screws.  Some times that gasket dries out a bit.

[N601RX]

Quote: tony

Rage, does you tank still leak if it’s half full?  Before you dive into a reseal, you should check the gasket where the sending unit penetrates the fuselage and snug up the screws.  Some times that gasket dries out a bit.

[KSMooniac]

JV,

Mooney fuel tanks get more attention than most other airplanes with wet wings due to the design/construction of the Mooney.  The landing gear shock absorption "system" consists of rubber biscuits instead of oleo struts or bungees, and the main gear of course bolt right into the strong and stiff Mooney wing.  Over time, the biscuits wear out and allow more shock to get transmitted into the wing and fuel tanks.  Owners that don't replace the biscuits often enough and/or operate from very rough strips routinely will accelerate the demise of the tanks.  Consider your 182 example...it has a more forgiving landing gear system and a fuselage to dissipate ground loads before getting into the wing, so those tanks see significantly less shock over time compared to a Mooney.

[N207LS]

 I have been happy with the reseal from Wet Wingologists at KFXE.  Work is good and Edison was a fair and honest person to deal with.  I am almost 3 years with no leaks...  Maybe a good vacation to visit South Florida and have the work done while you enjoy the beach...

[Piloto]

There are essentially two ways of making integral tanks and each has it plus and cons. Most Mooney tanks are coated with sealant after the wing has been assembled. On newer Mooneys the sealant is sandwiched in the structure during wing assembly like on most jets and other planes. On tanks were the sealant is coated (not sandwhich) after assembly are more prone to leak if the sealant bonding degrades. While on those were it is sandwhich during assembly the sealant is held in place not only by the bonding properties but by the pressure of the assembled structure on the sealant. Coating after wing assembly is an easier less laborious process than sealant sandwhich. The greatest cause of sealant deterioration is heat. Sealant like any rubber looses it elasticity over time when exposed to heat and has tendency to shrink an crack thus causing leaks. Best way to avoid leaks is to avoid long term heat on the wing. Hangar storage is the best way but if not available fuel in the tank will help on keeping the temperature down. Half full or more will considerably keep the temperature down during the summer. Some may argue that hard landings will cause leaks but if that was the case you would have serious structural problem that causes the sealant to fail. Keep in mind that sealant has considerable more elasticity than aluminum.

Jose

    

[SkyPilot]

Quote: Piloto

You will notice that none of the new popular planes use bladders anymore. Aside for the bladder payload penalty there are other issues to consider. With a single can of sealant you can fix the tanks of a Mooney all the way up to a B777. MROs no longer have to stock different bladders like for the B707 but just a few cans of sealant. With bladders you could be in trouble if an specific bladder replacement is not available. With integral tanks you don't need to worry about finding material to fix either side. If not inspected on a routine basis bladders can cause corrosion to the main spar by trapping moisture between the bladder material and the structure (an annoying problem on the B707). Water entrapment created by bladder wrinkles is another problem found on the early C172. Fixing a bladder leak takes a longer time than an integral tank. Not to mention if you need to order a new bladder. Mooneys with bladders are not compatible with long range tanks option.

José

[SkyPilot]

Quote: tony

Rage, does you tank still leak if it’s half full?  Before you dive into a reseal, you should check the gasket where the sending unit penetrates the fuselage and snug up the screws.  Some times that gasket dries out a bit.

[jetdriven]

FWIW my plane had bladders installed 19 years ago.  No leaks, a 960 LB useful load, and no trapped water in wrinkles. If Willmar or Maxwell will warranty their resela for 20 years, go with them.  30 pounds is nothing.

[Alan Fox]

Make sure the tanks are full when you pre purchase all the way ....  After it sits for an hour or two follow your nose.... If you smell ANY fuel the tanks leak...