Tank seal vs Bladder

[Hank]

7 hours ago, jetdriven said:

They are installed in the wings cavities that were formerly full of fuel, sealed and coated with the red Buna-n rubber. I don’t see how water trapped in there can harm the airframe since it’s sealed anyway. 

Because bladders are installed when the sealant is in bad shape and won't keep the fuel inside anymore?

[Guest]

On 6/4/2018 at 10:40 PM, Piloto said:

Not a bad idea to remove the bladders after 30 years and check for corrosion at the next annual. 

José

The same should hold true for sealed wings.  There have been more than a few on this site that found corrosion on their spars when the tank was opened.

You go first and report back!

Clarence

[rbridges]

I wasn't happy about losing 29lbs of useful load, but I've gained 10-15lbs myself since owning the mooney, and the plane isn't giving me the 3rd degree.  lol

[jetdriven]

1 hour ago, Hank said:

Because bladders are installed when the sealant is in bad shape and won't keep the fuel inside anymore?

It’s usually because the tank was leaking in a couple places in the six wing bays. But 99% of the sealer is still functional, id guess good enough not to corrode while the bladder is in there. 

The corrosion under the tank sealer is interesting. It looks like it starts from the wheel well and migrated forward. I think a likely culprit is people using cleaning solutions and stripper in the wheel well. The spar and the skin edge are exposed there. Anything sprayed or wiped there is going to get pulled forward, between the skin and the spars due to capillary action. 

[Piloto]

8 hours ago, jetdriven said:

Definately. It is the difference between a 750nm airplane and and 900nm one.  Need an IfR alternate then subtract 100nm from each 

Keep in mind that a plane with bladders has less useful load in fuel (5 gallons less) due to the added weight of the bladders.

José

Edited June 7, 2018 by Piloto

[Piloto]

1 hour ago, M20Doc said:

The same should hold true for sealed wings.  There have been more than a few on this site that found corrosion on their spars when the tank was opened.

You go first and report back!

Clarence

My first Mooney was a 1966 M20C based at TJIG right at the San Juan bay in PR. It had corrosion on the tubing structure and on the wing spar (center splice and wheel wells) but none inside the fuel tanks. During repairs I had to open the tanks for drilling out the rivets that hold the vertical stiffeners in the wheel well. But the tanks inside didn't have corrosion. 

José

[jetdriven]

2 hours ago, Piloto said:

Keep in mind that a plane with bladders has less useful load in fuel (5 gallons less) due to the added weight of the bladders.

José

How much weight does your long range tank mod add, Jose? I mean several cans of sealer, buna-N topcoat.  Additional fuel caps and accces panels and doublers.

i actually am of the idea that sealed integral wing tanks are the way to go, but in this specific application I’m  not impressed. Most of the fleet has some leak somewhere. Ten grand for a whole strip and reseal yet even those leak after a few years, requiring a 1,000$ trip to the installing shop for warranty work    .  At some point we should admit that it’s not a “once and done” sure fire fix for chronic Mooney tank leaks.  Despite having now the third engine booties onto my plane, I’m very specific to fix something once and forever.  Our plane came with 20+ year old bladders because the previous owner spent several grand and 3 attempts to patch the left tank.  

Everyone here is quick to add the smooth belly mod which adds no performance at all and loses 29lbs, or keep their old KX-170B com2 when they Install whole new IFR GPS kit,  but when bladders are involved, oh the humanity over 29lbs. Unacceptable. 

Edited June 7, 2018 by jetdriven

[mooniac15u]

On 6/4/2018 at 10:47 PM, Bob_Belville said:

José, sounds like a pretty bad (somewhat expensive) idea to me.  I think I'll wait for the AD. Or a "mandatory" SB. Or a few actual cases where corrosion was found. 

You could probably just spray some WD-40 between the bladders and the airframe.  I hear it provides superior corrosion protection and lubrication.

[Marauder]

I also question

1 minute ago, mooniac15u said:

You could probably just spray some WD-40 between the bladders and the airframe.  I hear it provides superior corrosion protection and lubrication.

LOL! I am still trying to figure out how much of Jose's relief tube lubricant is ending up in the plane through seams.

[Marauder]

As I suspected this topic has brought up all the usual arguments for and against bladders with not much info on perceived or real safety.  As I stated  I had already made my decision and with the simple back log at the shop has given me to rethink the safety issue. 
[mention=7104]carusoam[/mention] I have the fancy CIES sending units ready to be installed and the JPI EDM 900 recently installed.  I will provide a PIREP when after the tank work and sending units are complete.
However, to add a little fuel to the fire what if the bladder added no additional weight, cost the exact same as a reseal, resale value add-on was the same, and corrosion issues were the same?

Troublemaker!!


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[Marauder]

The same should hold true for sealed wings.  There have been more than a few on this site that found corrosion on their spars when the tank was opened.
You go first and report back!
Clarence

And I wonder how many planes with TKS systems will or do have corrosion issues.


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[Piloto]

1 hour ago, jetdriven said:

How much weight does your long range tank mod add, Jose? I mean several cans of sealer, buna-N topcoat.  Additional fuel caps and accces panels and doublers.

 

Ten pounds total both sides and you gain 36 gallons.

José

[Marauder]

8 hours ago, Piloto said:

Keep in mind that a plane with bladders has less useful load in fuel (5 gallons less) due to the added weight of the bladders.

José

Ok! I won't stop at Burger King on the way to the airport!

[Piloto]

25 minutes ago, Marauder said:

Ok! I won't stop at Burger King on the way to the airport!

Good idea because the consequences could have a bad smell.

José

[Marauder]

Just now, Piloto said:

Good idea because the consequences could have a bad smell.

José

The girls will be disappointed.. 

[N6758N]

20 hours ago, jetdriven said:

That looks like a lot of corrosion between the fuselage frames and on the longerons but what do bladders have to do with this? 

They trap moisture...or they did in this case. The bladders sit in between those frames.

[jetdriven]

2 hours ago, N6758N said:

They trap moisture...or they did in this case. The bladders sit in between those frames.

It looks like the corrosion started and is the worst here. I don’t think bladders are sitting in that area, Are they? 

 

[carusoam]

Looks like the aluminum was painted with the Zync chromate after it was assembled....

Was this Otter a sea plane at one time?

Mooney changed up the fuel tank sealing procedure for the Long Bodies...  some parts were coated with something prior to assembly...

Well that’s a fuzzy memory that got away!

Best regards,

-a-

[Igor_U]

7 hours ago, carusoam said:

Looks like the aluminum was painted with the Zync chromate after it was assembled....

Was this Otter a sea plane at one time?

Wow!

What are we looking at here? This came from DHC Otter? It does look like removed skins off the structure. Fuselage or wing?

I seriously doubt Zinc chromate was applied after assy as you can see traces on the flanges after skins were removed. If this really comes from Otter, I'm not really surprised. Those are working birds, flown hard and put away wet (literary). Also, back in a day corrosion control had a ways to go even with big OEMs. There was clearly no fay surface seal applied between skin and rib flanges. Also, floatplanes are very susceptible to corrosion due to their working environment, being operated off salty water just increases the risk. DHC plane have a reputation of being sturdy and long lived but all those Beavers and Otters flying commercially have been restored multiple times and great cost.

One thing for sure, corrosion control is much better nowadays and big OEMs pay a lot of attention to proper design and processes with keel of the fuselage getting special attention. Zinc chromate hasn't been used in decades (very cancerogenous) and was replaced by better epoxy primers; different sealants are used for fay surface sealing and fillet sealing at assembly and fuel tanks have their own primer and sealant formula as well.

 

[Piloto]

Working planes don't get hangared.

José

[johncuyle]

Preference thing.  Right now I have 72 usable gallons.  I usually only fuel to 60.  Bladders would limit me to 64 and I'd have to fuel to 55.  I'd be much more interested in adding the Monroy long range tanks to get fuel capacity up to 105 gallons and having the option to do very long distance flights solo than losing 8 gallons max and 5 most of the time just to not have the leaks that I already hopefully won't have for a long time.

[Hank]

1 hour ago, johncuyle said:

Preference thing.  Right now I have 72 usable gallons.  I usually only fuel to 60.  Bladders would limit me to 64 and I'd have to fuel to 55.

Why not put in 64 gallon bladders and fuel to 64 gal? Why limit it to 55 gal? This doesn't make sense. At the beginning of a flight, I fill mine to the top; when refueling after a flight, I leave 1/2" to 1" of space for the fuel to heat up and expand without overflowing. But leaving out 4-1/2 gallons per side? I'm confused . . . . .

[johncuyle]

On ‎6‎/‎8‎/‎2018 at 12:16 PM, Hank said:

Why not put in 64 gallon bladders and fuel to 64 gal? Why limit it to 55 gal? This doesn't make sense. At the beginning of a flight, I fill mine to the top; when refueling after a flight, I leave 1/2" to 1" of space for the fuel to heat up and expand without overflowing. But leaving out 4-1/2 gallons per side? I'm confused . . . . .

To stay under max gross while carrying as much fuel as possible.

[irishpilot]

I went through this same decision when my M20E needed a reseal. The cost and down time was the main consideration. If you feel 55 gal is restrictive, then seriously consider bladders. If you go for a reseal, make sure whoever does it is not a Mooney novice. It's a nasty job and whoever does it better do it right otherwise you'll be chasing different leaks or worse, you'll have debris in the tanks which is a safety hazard.

 

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[LANCECASPER]

The search feature on Mooneyspace is your friend

 

http://www.monroyaero.com/lrupgad.pdf

etc, etc, etc . . .