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rocknpilot(at)hotmail.com
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 Posted: Fri Aug 15, 2014 1:45 pm Post subject: Fuel Tank Repairs |
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Hi All! I went up for a nice dusk flight Thursday PM. After doing a bit of a zoom climb to a comfortable altitude for a local flight, I noticed an overwhelming aroma of raw fuel wafting into the cockpit. With no visible sign of leakage or pooling, prudence nevertheless dictated a return to home base. Following a normal shutdown, I was rewarded with the wonderful sight of no smoke / fire, but I jumped off the wing to find fuel streaming from my right tank seams. Upon siphoning remaining gas and pulling the fuel tank access panel, I spotted a hairline fracture right on the stiffning bead of the tank - immediately aft of the breather. I took the tank to a few local shops for repair and received a unanimous NO WAY - NOT TOUCHING IT! - partially due to liabilities but mostly due to them being hypersensitive to instantaneous combustion. One guy offered the idea of using a sloshing compound and said motorcycle shops typically carry a good one. I see Aircraft Spruce has quite a few as well. But even then he said I'd need to thoroughly "defume" the tank - which he described a exceedingly difficult to accomplish.
As w/ many aspects of the Yak, this is a new obstacle for me. Before I dive into reinventing the wheel, I believe in asking those in the know....
My questions are:
1) Are Yak fuel tanks a weak point of the aircraft? I can't recall this subject coming up while I've been a "lurker" - but you know how things aren't as interesting until they're happening to YOU, so I may've missed it.
2) Has anyone been down this road (fuel tank ruptures) and what have you found that works / is safe / etc?
As always, I am eager to hear from the experts and ever so grateful for ANY input on this topic - whether you've encountered it personally or simply have a great idea!
Thank you, EVERYONE!
Rico Jaeger
915 S. 11th Ave.
Wausau, WI. 54401
715.529.7426
//
1966 Cessna 150F ^/---//-X
N8558G //
//
1992 Yakovlev Yak 52 ^/---//-X
N21YK //
[quote][b]
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dsavarese0812(at)bellsout
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| Posted: Fri Aug 15, 2014 2:13 pm Post subject: Fuel Tank Repairs |
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Rico,
The Yak 52 fuel tanks have been known to crack. This is due to the constant expansion and contraction due to heating and cooling of the fuel. The existing vent system, unless your airplane is an '89 or later model, contributes to the problem. Eventually, due to the expansion and contraction, the metal cracks. Usually they crack either along a weld seam or just under one of the straps. Mine actually cracked directly below the filler cap, which was not on a seam or strap. It was easy to repair with ProSeal because it was easy to get to. ProSeal is an approved aircraft fuel tank repair material available from Aircraft Spruce. Others sell it as well. Your only real alternative is to have it welded.
You have to find a welder who will weld fuel tanks. And you don't have to tell him it is from an airplane. It's from your Czech-made farm tractor or something.
Save your pennies and upgrade to the Yak 52 fuel bladders. They eliminate this problem forever and you'll get another hour of useable fuel making the airplane a true 2 1/2 hour endurance with 30 minutes reserve. Contact me off-list if you're interested or go to my web site for more info.
Dennis
| Quote: | A. Dennis Savarese
334-285-6263
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1 |
On 8/15/2014 4:43 PM, Rico Jaeger wrote:
[quote] Hi All! I went up for a nice dusk flight Thursday PM. After doing a bit of a zoom climb to a comfortable altitude for a local flight, I noticed an overwhelming aroma of raw fuel wafting into the cockpit. With no visible sign of leakage or pooling, prudence nevertheless dictated a return to home base. Following a normal shutdown, I was rewarded with the wonderful sight of no smoke / fire, but I jumped off the wing to find fuel streaming from my right tank seams. Upon siphoning remaining gas and pulling the fuel tank access panel, I spotted a hairline fracture right on the stiffning bead of the tank - immediately aft of the breather. I took the tank to a few local shops for repair and received a unanimous NO WAY - NOT TOUCHING IT! - partially due to liabilities but mostly due to them being hypersensitive to instantaneous combustion. One guy offered the idea of using a sloshing compound and said motorcycle shops typically carry a good one. I see Aircraft Spruce has quite a few as well. But even then he said I'd need to thoroughly "defume" the tank - which he described a exceedingly difficult to accomplish.
As w/ many aspects of the Yak, this is a new obstacle for me. Before I dive into reinventing the wheel, I believe in asking those in the know....
My questions are:
1) Are Yak fuel tanks a weak point of the aircraft? I can't recall this subject coming up while I've been a "lurker" - but you know how things aren't as interesting until they're happening to YOU, so I may've missed it.
2) Has anyone been down this road (fuel tank ruptures) and what have you found that works / is safe / etc?
As always, I am eager to hear from the experts and ever so grateful for ANY input on this topic - whether you've encountered it personally or simply have a great idea!
Thank you, EVERYONE!
Rico Jaeger
915 S. 11th Ave.
Wausau, WI. 54401
715.529.7426
//
1966 Cessna 150F ^/---//-X
N8558G //
//
1992 Yakovlev Yak 52 ^/---//-X
N21YK //
[b]
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cpayne(at)joimail.com
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| Posted: Sat Aug 16, 2014 2:40 am Post subject: Fuel Tank repairs |
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Rico,
Your best bet is to contact local EAA Chapters or someone at nearby Oshkosh for a home builder who can do this. Down here in Lakeland, everyone goes to a good ole boy living out near the swamp. He works wonders with his TiG setup, installed in a lean-to off his single wide. There might not be any swamp nearby in Wisconsin but I'm sure there's a good ole boy with a TiG setup in his garage nearby. You just have to ask around, car guys know who to go to also, seek out some of them.
Craig Payne
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Dale
Joined: 30 May 2007
Posts: 178
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| Posted: Sat Aug 16, 2014 2:34 pm Post subject: Re: Fuel Tank Repairs |
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Weld it. You will be damn sorry you used sloshing compound down the road.
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rocknpilot(at)hotmail.com
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| Posted: Sun Aug 17, 2014 5:11 pm Post subject: Fuel Tank Repairs |
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Dennis, Craig, Bob and Dale -
Thanks for the replies. I have a miracle welder (DOUBLE-wide, Craig! looking at the tank tomorrow. If that doesn't pan out, I feel confident I can plug this leak safely in an alternative form. I really appreciate the input. I should've mentioned my Yak is a '92 and the crack is immediately below the fill neck on the bottom tank skin.
I plan on posting most of my trials and (hopefully) successful fixes on the List. I figure that's what it's for...to learn. I've put a lot of work and time into N21YK to bring it back functionality, so these "speedbumps" won't hangar me for long!
Again..THANK YOU ALL! Much appreciated!!
Rico Jaeger
915 S. 11th Ave.
Wausau, WI. 54401
715.529.7426
//
1966 Cessna 150F ^/---//-X
N8558G //
//
1992 Yakovlev Yak 52 ^/---//-X
N21YK //
[quote] Subject: Re: Fuel Tank Repairs
From: dale(at)frii.com
Date: Sat, 16 Aug 2014 15:34:49 -0700
To: yak-list(at)matronics.com
--> Yak-List message posted by: "Dale" <dale(at)frii.com>
Weld it. You will be damn sorry you used sloshing compound down the road.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=428580#428580
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dsavarese0812(at)bellsout
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| Posted: Sun Aug 17, 2014 5:27 pm Post subject: Fuel Tank Repairs |
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If you use useUse the ProSeal, you don't have to remove the tank. The crack in your tank is in the exact same location mine was. Very easy to repair with ProSeal and will last indefinitely. Before you purchase some, check with your local A&P as he may have some on the shelf and you certainly don't need much. http://www.aircraftspruce.com/catalog/appages/ps890.php?clickkey=289499
You'll save a lot of time doing the repair this way.
Dennis
| Quote: | A. Dennis Savarese
334-285-6263
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1 |
On 8/17/2014 8:11 PM, Rico Jaeger wrote:
| Quote: | Dennis, Craig, Bob and Dale -
Thanks for the replies. I have a miracle welder (DOUBLE-wide, Craig! looking at the tank tomorrow. If that doesn't pan out, I feel confident I can plug this leak safely in an alternative form. I really appreciate the input. I should've mentioned my Yak is a '92 and the crack is immediately below the fill neck on the bottom tank skin.
I plan on posting most of my trials and (hopefully) successful fixes on the List. I figure that's what it's for...to learn. I've put a lot of work and time into N21YK to bring it back functionality, so these "speedbumps" won't hangar me for long!
Again...THANK YOU ALL! Much appreciated!!
Rico Jaeger
915 S. 11th Ave.
Wausau, WI. 54401
715.529.7426
//
1966 Cessna 150F ^/---//-X
N8558G //
//
1992 Yakovlev Yak 52 ^/---//-X
N21YK //
> Subject: Re: Fuel Tank Repairs
> From: dale(at)frii.com (dale(at)frii.com)
> Date: Sat, 16 Aug 2014 15:34:49 -0700
> To: yak-list(at)matronics.com (yak-list(at)matronics.com)
>
> --> Yak-List message posted by: "Dale" <dale(at)frii.com> (dale(at)frii.com)
>
> Weld it. You will be damn sorry you used sloshing compound down the road.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=428580#428580
>
>
>
>
>
>
>
[/b] |
[b]
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mark.bitterlich(at)navy.m
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| Posted: Mon Aug 18, 2014 7:58 am Post subject: Fuel Tank Repairs |
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Dale,
I do not believe anyone recommended "sloshing compound", which by the way, I would not recommend either.
What was recommended was Pro Seal which is an 8802 MILSPEC based compound which is specifically created (and used extensively in the military) to seal a leak of this exact type. This is an external sealant, and is not put inside the tank. The only caution is to follow the instructions to the letter regarding cleaning and prep of surfaces.
I would NOT recommend "welding it" given the nature and location of this leak for a variety of reasons.
Welding these type of tanks is tricky business and FYI, I have used 8802 sealant on a tank leak in my 50 that has passed muster for 14 years without a problem. I think that kind of speaks for itself, also given that we used the exact same stuff on multiple military aircraft.
Mark
--
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mark.bitterlich(at)navy.m
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| Posted: Mon Aug 18, 2014 8:07 am Post subject: Fuel Tank Repairs |
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Dale,
OK, I take it back... some less than bright person unnamed somewhere along the line did recommend sloshing compound. Ooops. Sorry. I had to go back reading through all of the message strings to get it out of the original message Rico wrote.
Rico,
If you want to weld it, there is an old trick that actually works to prevent tank explosions... basically the proper way to do this is to constantly vent the tank with an inert gas like water pumped nitrogen to displace fuel fumes. If you really want to do it right, there is a compound sold that you put in the tank, fill it full of water and let it sit for about a week. The old time welders trick is to put a hose on the exhaust of a running car, lawn mower, etc., , and put that hose inside of the fuel tank. The carbon monoxide gas will displace and absorb oxygen and a spark will not cause the tank to explode. This actually works, and I have done it myself. Take some brass "you know what" to do it though.
The best fix under the circumstances is ProSeal or any 8802 based compound. Never-the-less, the tank still is going to need to be cleaned down to bare metal and thus using the exhaust fumes into the tank trick is still a good idea even if all you're using on the thing is a wire brush. Whatever you do, do something... even filling it full of water while prepping it. It is real bomb waiting to go off otherwise.
Mark
--
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Viperdoc
Joined: 19 Apr 2014
Posts: 484
Location: 08A
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| Posted: Mon Aug 18, 2014 10:17 am Post subject: Fuel Tank Repairs |
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Ditto. ProSealed my main tank in the 50 5 years ago. Works great. After cleaning the tank down to bar metal, I applied a dye penetrant to re-define the crack. Then sanded the surface with coarse sand paper to rough up the surface real well. I then applied Pro Seal to the external surface ( the part I hand sanded down to bare metal).
Doc
Sent from my iPad
[quote] On Aug 18, 2014, at 10:56 AM, "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil> wrote:
Dale,
I do not believe anyone recommended "sloshing compound", which by the way, I would not recommend either.
What was recommended was Pro Seal which is an 8802 MILSPEC based compound which is specifically created (and used extensively in the military) to seal a leak of this exact type. This is an external sealant, and is not put inside the tank. The only caution is to follow the instructions to the letter regarding cleaning and prep of surfaces.
I would NOT recommend "welding it" given the nature and location of this leak for a variety of reasons.
Welding these type of tanks is tricky business and FYI, I have used 8802 sealant on a tank leak in my 50 that has passed muster for 14 years without a problem. I think that kind of speaks for itself, also given that we used the exact same stuff on multiple military aircraft.
Mark
--
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wlannon(at)shaw.ca
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| Posted: Mon Aug 18, 2014 9:11 pm Post subject: Fuel Tank Repairs |
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Mark;
There are a number of aerospace fuel tank sealants that meet MIL S 8802.
Pro Seal is a PPG product. I believe PPG and the traditional DE-Soto
products (PR 1422, etc.) are now all under the same banner as PRC (Products
Research Corp.)
All that meet MIL S 8802 are intended for internal sealing of integral fuel
tanks.
That is not to say that they cannot be used externally given correct surface
preparation. But sealing of a crack in this manner is questionable in that
they are (and need to be) flexible and in no way will they stop a crack from
progressing if the forces causing the crack are still extant.
I too would not recommend sloshing compounds.
Walt
--
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fish(at)aviation-tech.com
Guest
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| Posted: Mon Aug 18, 2014 10:22 pm Post subject: Fuel Tank Repairs |
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Rico,
I once TIG welded an aluminum top fuel racing fuel tank. I stop drilled the cracks to relieve the stresses. Then filled the tank 3/4 full of water and, purged with carbon dioxide, before TIG welding the crack.
Later in the Air Force, as a fuel system mechanic, I used the 8802 sealants to seal fuel tanks on aircraft. Probably the easiest method for you to use would be the 8802 sealant method. Follow the directions for prepping the area. Attempt to locate the ends of the cracks, and stop drill them to relieve the stress. (Sometimes when you drill what you believe to be the end, you discover the crack continues past your drill point. If so, continue drilling a little bit further until you locate the end), (another procedure I have used welding cast iron, is to use a small disc and open the crack to locate the end).
While we normally used the sealant inside the tanks. but occasionally a field expedient repair was to use it outside to stop the leak. Then when we got more time, we would enter the tank and do leak path analysis and scrap the sealant inside the tank and reseal. One leak on a KC-135, showed up approx 10' away from where the leak was inside the tank.
I believe the sealant will outlive your using the aircraft, and if not it would be simple to redo the repair again.
Good luck
John Fischer
Yak-52, N213YA
BT-13, project
L-5, project (x3)
PT-19, project (x2)
Sent from my iPad
[quote] On Aug 18, 2014, at 10:09 PM, "Walter Lannon" <wlannon(at)shaw.ca> wrote:
Mark;
There are a number of aerospace fuel tank sealants that meet MIL S 8802. Pro Seal is a PPG product. I believe PPG and the traditional DE-Soto products (PR 1422, etc.) are now all under the same banner as PRC (Products Research Corp.)
All that meet MIL S 8802 are intended for internal sealing of integral fuel tanks.
That is not to say that they cannot be used externally given correct surface preparation. But sealing of a crack in this manner is questionable in that they are (and need to be) flexible and in no way will they stop a crack from progressing if the forces causing the crack are still extant.
I too would not recommend sloshing compounds.
Walt
--
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