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PHCarter(at)aol.com
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 Posted: Sat Jul 15, 2006 4:23 pm Post subject: Yak52 fuel tank leaks |
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A year ago, flying back from OSH, I developed a fuel leak in my right wing tank. Repaired it easy enough (crack across one of the reinforcing beads along the bottom). Now a year later, I have developed another leak (also the right tank). Have not jumped into repairing it yet, but here is the question: Could I have a vent problem that is allowing the tank to pressurize with summer heat, or as I fly, and cause these cracks? In the summer, I leave my tank caps lose so pressure does not build up (still waiting for a hanger, so outside 24/7), so I don't think pressure is a problem. My tanks appear to vent properly and my Aux tank pumps into my wing tanks properly, so I don't recognize any other problem other then frequency tank cracks/leaks.
Are leaks like this common? (1 a year on average) How do I test that my fuel vent is clear and open? Is there another source of this problem I don't know about? As always, thanks for whatever insight you can provide.
Preston Carter
Yak52 N6209F
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cjpilot710(at)aol.com
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| Posted: Sat Jul 15, 2006 7:48 pm Post subject: Yak52 fuel tank leaks |
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Preston,
I don't think you have a pressure problem. Most likely your tank may have built in structural stresses that when subjugated to vibration of operation, cause the welded seams to crack. Also the tank will expand and contract with heat of the ambient air. If the welded seams are under tension (maybe happened during construction or repair ) than they can crack. Also the weld it self could have small imperfection bought on by the welder or materials used.
Pressure problems in a fuel system would almost show up as fuel feed problems to the engine before they would ever get to the point where it would crack tank metal.
Leaks are not common but not unknown in either the Yak nor CJs.
Jim "Papppy" Goolsby
A year ago, flying back from OSH, I developed a fuel leak in my right wing tank. Repaired it easy enough (crack across one of the reinforcing beads along the bottom). Now a year later, I have developed another leak (also the right tank). Have not jumped into repairing it yet, but here is the question: Could I have a vent problem that is allowing the tank to pressurize with summer heat, or as I fly, and cause these cracks? In the summer, I leave my tank caps lose so pressure does not build up (still waiting for a hanger, so outside 24/7), so I don't think pressure is a problem. My tanks appear to vent properly and my Aux tank pumps into my wing tanks properly, so I don't recognize any other problem other then frequency tank cracks/leaks.
Are leaks like this common? (1 a year on average) How do I test that my fuel vent is clear and open? Is there another source of this problem I don't know about? As always, thanks for whatever insight you can provide.
Preston Carter
Yak52 N6209F
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dsavarese(at)elmore.rr.co
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| Posted: Sun Jul 16, 2006 5:09 am Post subject: Yak52 fuel tank leaks |
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Preston,
Leaks like the one you are describing are not common in the Yak 52. Although I have seen a couple of leaking fuel tanks, all leaks were at a seam. Your venting procedure is precisely the same procedure that most all Yak 52 owners have learned to use. Except for the '90 models and up (could be the '89 model and up too), which have a double vent line (one for each tank) with 2 vent tubes protruding underneath the fuselage instead of one, Yak 52's with 35-40 liters of fuel in both tanks sitting in the sun will "puke" fuel overboard through the single vent tube. It's just a poorly designed vent system which as I said, was redesigned and greatly improved with the '90 model and up.
My thought is you simply have a second crack in one of the seams. You may want to have all the seams rewelded when you pull the tank out for repair.
Dennis
[quote] ---
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wade154(at)frontiernet.ne
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| Posted: Sun Jul 16, 2006 7:19 am Post subject: Yak52 fuel tank leaks |
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Preston
I've had two leaks from what I would call oil canning cracks and repaired both with a two part epoxy from loctite 9460 Hysol and fiberglass cloth and the repairs have held for a couple years now. I think the reason for my cracks are I do a lot of acro and pull 4-4.5 on most outings or 0 lbs. at the top of a loop to 312 at the bottom and straight and level 78 lbs, so I can see why it would oil can. The leaks that I have repaired were found just after such an outing and in the center bottom of the tank. My Yak is 1985 vintage it has two straps holding each fuel tank in place I've seen newer models with three straps holding the fuel tank in, which would really help stop the oil canning in the center where my leaks were repaired. Its quite possible that the older Yaks that were stressed to 5 gs had two straps and when the 7 g spar mod came out and the boys and girls started pulling 7+ gs the factory found that another strap solved the problem.
Bill Wade
N4450Y
[quote] ---
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netmaster15(at)juno.com
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| Posted: Mon Jul 17, 2006 12:28 am Post subject: Yak52 fuel tank leaks |
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Hi Bill,
I found your post of Sunday, 16 July potentially helpful to my problem. You wrote"....repaired both with a two part epoxy from Locktite 9460
Hysol and fiberglass cloth...". I'm not familiar with these materials ( specifically the Locktite 9460 and the two part epoxy} and I want to repair a fuel seepage leak on the side of a fiberglass tip tank in my A 36 Bonanza. Would you please print out for me the procedure you employ to prepare and apply the materials used to make your fix? I also own and fly a YAK 50 and although this Bonanza thing is a bit off topic I hope to cure that problem using your method. Thankyou for your assistance.
Cliff Umscheid
On Sun, 16 Jul 2006 11:16:04 -0400 "the wades" <wade154(at)frontiernet.net (wade154(at)frontiernet.net)> writes:
[quote] Preston
I've had two leaks from what I would call oil canning cracks and repaired both with a two part epoxy from loctite 9460 Hysol and fiberglass cloth and the repairs have held for a couple years now. I think the reason for my cracks are I do a lot of acro and pull 4-4.5 on most outings or 0 lbs. at the top of a loop to 312 at the bottom and straight and level 78 lbs, so I can see why it would oil can. The leaks that I have repaired were found just after such an outing and in the center bottom of the tank. My Yak is 1985 vintage it has two straps holding each fuel tank in place I've seen newer models with three straps holding the fuel tank in, which would really help stop the oil canning in the center where my leaks were repaired. Its quite possible that the older Yaks that were stressed to 5 gs had two straps and when the 7 g spar mod came out and the boys and girls started pulling 7+ gs the factory found that another strap solved the problem.
Bill Wade
N4450Y
[quote] ---
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wade154(at)frontiernet.ne
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| Posted: Mon Jul 17, 2006 7:15 am Post subject: Yak52 fuel tank leaks |
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Cliff
I found this stuff by purchasing a Kitfox (small homebuilt airplane) and found the epoxy used to secure the wood ribs to the front and rear aluminum spar's originally was a 3M product that worked really well at bonding to just about anything, when I wanted some more and contacted them they informed me that they stopped using the 3M product and are currently using the Loctite product. I then found my closest Loctite distributor and ordered a quart each of epoxy and hardener. This stuff gets really hard after curing and bonds to anything, if you could get inside the tank I would use pro seal that stays a little rubbery after curing and is made to work with 100LL. I probably didn't have to add the fiberglass but thought it would help as on my repair I covered the whole bottom with a thin layer of epoxy and fiberglass cloth (not matt) be sure that the epoxy wicks up through the fiberglass, and another thin layer on top of the fiberglass. Remove the tank clean the surface thoroughly and ruff it up with a wire brush, it sets in about an hour and takes about 24 hours to cure. If your doing a small job I've seen Hysol in small tubes at our local auto parts store. Again the product is Loctite Hysol 9460.
[quote] ---
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wade154(at)frontiernet.ne
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| Posted: Tue Jul 18, 2006 4:17 am Post subject: Yak52 fuel tank leaks |
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Cliff
Now the disclaimer if you plan on using it on your FAA certified aircraft please look at the manufactures maintenance manual and consult an A&P mechanic before using the product procidure..
[quote] ---
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netmaster15(at)juno.com
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| Posted: Tue Jul 18, 2006 10:36 pm Post subject: Yak52 fuel tank leaks |
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Bill,
Re Disclaimer, Not to worry; I'm the IA on my aircraft and I'm not planning to fill out any 337s when not necessary. Again, thanks for your help.
Regards,
Cliff
On Tue, 18 Jul 2006 08:14:24 -0400 "the wades" <wade154(at)frontiernet.net (wade154(at)frontiernet.net)> writes:
[quote] Cliff
Now the disclaimer if you plan on using it on your FAA certified aircraft please look at the manufactures maintenance manual and consult an A&P mechanic before using the product procidure..
[quote] ---
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