Fuel Tank 337G

edasmus · #1 03-30-13, 09:05 AM

My left side (pilot side) inboard fuel tank, part number 1516057-1 is cracked. This problem started as a slow leak at some fitting on the tank. I was seeing fuel staining at the wing root. Shop thinks they cracked the tank when they removed the fitting to replace it. They have attempted to weld it and after having the tank in and out four times, it still leaks. Now they want me to find a replacement tank. I have emails into Qwen Bell and Don Neiser. Anyone have a tank or any other ideas?

Thanks, Ed

Airplane is a 1973 C337G

Accidently posted in the "Parts For Sale" section. Didn't mean to do that.

James Bennon · #2 03-30-13, 06:43 PM

Try Preferred Airparts, Kidron, Ohio 1.800.433.0814

edasmus · #3 03-30-13, 09:10 PM

On my list to call Monday. Thanks for the help.

Ed

Mark Hislop · #4 03-31-13, 08:40 PM

Hi Ed.

There is a guy on ebay who is parting out a 337D. I think the tanks are the same. Here is a link to one of his auctions for a different part, but you can find his contact information there.

http://www.ebay.com/itm/Cessna-337D-...17f77f&vxp=mtr

I bought an inboard flap last year off of another seller on ebay who was also parting out a plane. I think the sellers ebay name was baspartsales. You might try to track that down as well.

I am concerned that your shop "thinks" they have cracked a fitting. If it is the inboard tank, between the boom and the fuselage, there are only four 4 tank penetrations, plus the hole for the fuel level sender. Three of those penetrations are only tubes for a hose and clamp, and the fourth is a threaded boss for a compression fitting. If they have the tank out, it should be a simple matter to fill it with water and see if it is leaking or not.

I think I know the shop you are using, and they are good. But if the tank is in fact damaged, I think I would investigate sending it out to a shop that specialized in repairing aluminum fuel tanks. I find it hard to believe that your tank would not be repairable.

I feel your pain. Last year, I had a stain at the wing root. Fuel was leaking around the 40 year old cork gasket at the fuel sender on the inboard tank. I replaced the gasket, and the leak stopped for almost a year. When it started again, I tracked it down to the clamp around the 1 1/2" hose leading from the middle tank to the inboard tank. The fuel hose had shrunk from age. You can't get to the clamp without opening up the whole top of the wing. When I did, I found that most of the cork anti-chafe strips had migrated out from underneath the tanks. So I elected to take out the tanks, replace the cork strips, and replace all of the 40 year old hoses. I'm still working on it. It is the hardest thing I've ever done, but it will be worth it when I'm done. I hope.

edasmus · #5 03-31-13, 09:37 PM

Hey Mark,

Thanks for the info. I will investigate. I had a long talk with your IA last Thursday about your tank situation. He gave me all the details. I am quite aware of the complexity of our fuel system and over the years have considered complete removal, inspection, and repair. My shop (and yes you do know the one) has warned me about the enormity of that job and has convinced me to leave alone unless I see signs of trouble. This leak I have been chasing for a few months now. My right wing was showing trouble a few years back and replacing the cork sender gasket on that side cured that problem. When I started seeing trouble on the left side, the same cork gasket is where we started. We did see obvious signs of leakage there. About three months ago we replaced it but unfortunately that did not solve the problem this time. When we opened up that inboard panel a few weeks ago during the annual, that area was perfectly clean so we knew the leak was coming from somewhere else. The shop traced it to a fitting on the inboard tank between the boom and the wing root. They could clearly see blue staining all over the fitting and all over the bottom of the inside of the wing draining down to the wing root, which is where I was seeing it. The problem really got ugly after four attempts at re-installing the tank after the attempted repair and still leaking. Now they claim it appears to be leaking through a weld joint and they fear they cracked the tank while removing the old fitting. At least that is the story. I will know more in the morning. I actually have not spoken with the shop since the middle of last week. I have just been getting cursory emails from the IA with the bad news.

Stay tuned.

Ed

hharney · #6 03-31-13, 10:09 PM

Ed / Mark

The D model tanks do not have the large interconnect between the mid-main and the inboard aux. The D model has the older style main tank and independent auxiliary tanks. The G model like yours has all tanks interconnected and the D is separate mains and aux's. The D model also has a service port.

The G model is the blue figure attached and the D model is the white figure attached. That should explain the difference. Not sure I understand why the fitting cannot be repaired. I have had to repair a fitting like that on my main tank (inboard, mid) and it was welded with no issues. Sorry to hear the problems.

Gord Tessier · #7 03-31-13, 11:25 PM

I had a fuel leak in my 73 G model. It turned out to be nothing more then the gasket in the fuel cap. With the tanks full, I could see with a bright light the fuel migrating or weeping out around the filler cap and then down the wing root. Cheap fix.

hharney · #8 04-01-13, 09:13 AM

Gord

Very common area for Cessna. Sounds like based on the diagnosis that Ed gave above he has already been there done that. The gaskets on the fuel senders are troublesome critters and if you ever install a new fuel sender or gasket remember do not remove the wires at the terminal screw that has the putty on it. You have to take the wires apart at the butt connection or the unit is void for warranty if needed. Learn the hard way.

SkyMac · #9 04-01-13, 09:36 AM

Hi Herb

Any learnings on fitting the new gaskets, I will be replacing all mine before I close the wings. I have all the new gaskets and those little rubber washers ready to go. Mind you it will be a couple of months before I get to it.

I found two sender units leakering when I pulled the tank covers off, also I have read a few comments on leaking fuel tanks over the last couple of days. Of my 6 tanks and the two little sub tanks I will carry out in total 7 welds on very small splits / pin holes. Each repair is welded then it has another circular disc welded over that, according to the approved engineer who is conducting the repairs, this is a very common issue and he does them all to often.

Anyway I am aiming for a leak free fuel storage and supply

Regards
Dave

Mark Hislop · #10 04-01-13, 10:41 AM

Hi Ed.

If they were able to get the inboard tank in and out without removing the outer tanks, they are a lot smarter than I am. (Not a very high bar, I'm afraid.) I couldn't figure out a way to get new hoses on without removing all of the tanks and putting them in in sequence. For actual professionals with the right tools, I don't think it would be too tough. For an amatuer like me, well...... If you want to see what the outboard tank bay looks like, feel free to stop by my hangar any time. I'm there most evenings. I'm finishing up the left wing, and then starting the right wing.

Mark Hislop · #11 04-01-13, 10:44 AM

Thanks Herb. I didn't know that. Hopefully, Ed can find someone who is parting out a later model with the same tanks. Or get somebody to repair his tank.

hharney · #12 04-01-13, 02:43 PM

There was a G model being parted at the Middletown, Ohio airport. The local A&P there but not sure they have tanks, it would be worth a call

SkyMac · #13 04-01-13, 04:15 PM

The contact details for the 76 337G in Middletown are...

Kurt Yearout
Safe Skies Aviation
513-368-0282 (cell)
513-217-5141 (office)

kurtyearout@yahoo.com

hharney · #14 04-01-13, 10:00 PM

Dave

When replacing the sender gaskets be careful to not over tighten the fasteners as you can warp the tank metal around the opening. It's a little bit of a catch 22 as if you don't tighten enough it may leak but you don't want to bear down on them. Try to tighten in opposite sides from the other rotating around the sender. This will apply even pressure to the tank seal. If it still leaks then Pro Seal is the next step.

Cheers

edasmus · #15 04-02-13, 08:21 AM

Thanks everyone for all the info. Well when I got to the shop yesterday morning when they opened, the shop manager (who also does all the welding) was pulling up in his truck at the same time. He pulled my tank out of his truck and deemed it repaired. They installed it in about an hour and filled with fuel. NO LEAKS!! Apparently last Friday was quite a frustrating day for the shop and my tank but they refused to let the tank beat them. The manager took it home over the weekend and fixed it. The tank looked very good. I really don't know how to judge a weld but all the work he did looked very neat and clean. The tank looked nearly new all the way around. He charged me $300 to fix the leak. Something was leaking before the annual and now it is not (at least as far as I can tell, time will tell for sure). $300 seemed pretty good to me especially since the only quote I received was $3000 for a replacement tank from Owen Bell at Aviation Enterprises in TN.

Mark, when I get a chance, I will stop by. Thanks for your input.

Ed