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Thread: Stock PA-12 gear, stock fuel tank and strut questions

  1. #1
    txfirefighter628's Avatar
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    Stock PA-12 gear, stock fuel tank and strut questions

    Im looking at buying a PA-12, have one close to me picked out. I've search as much as I could on old threads but still have a few questions.

    1.) It has the stock PA-12 gear legs with the flat steel brace. Not sure if SB93(doesnt apply by serial #) or SB97 have been done, will have to look closer when I go look at the plane again. The left gear flat steel has a slight wrinkle/curve in it. Does this toatlly compromise this gear or can it be repaired? If the streamline tubing from SL 109 is added does it make it PA-14 gear?

    Piper service letter 113 recommends replacing with PA-14 gear, is the only new PA-14 gear availible the $1300 dollar per side univair gear?

    I've read that to convert to PA-18 gear two tabs need to welded on. Can this be done with the fabric on or if some has to be removed is it a easy repair? I plan on repainting the plane in the near future if I get it so a small fabric repair doesnt bother me. To do the 18 gear conversion you need 2 gear legs, the cabane V, 2 weld plates and 2 shock struts, any other parts required?


    2.) It has stock fuel tanks with the sight gauge that sticks out of the bottom of the wing. From what I have read from previous post the stock tanks are horribe, guarented to leak and not worth repairing. The easiet replacment I've seen are wag aero tanks but heard they are low quality too, have these tanks improved in quaility at all recently? Do the wag aero tanks have the stock location for the sight gauge or does it have fittings for the dakota cub stlye gauges.


    3.) The plane has atlee dodge wing lift struts installed and from the information I've found I belive these struts have a 5 or 7 year inspetion required. Is this correct? Also they have 1" fork fittings, to go to sealed lifetime struts with 5/8" fork fittings does anything on the fuselge or wing have to be repaired/replaced or can the 1" fork fittings be put on the sealed struts?

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    algonquin's Avatar
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    I'm building a 12 right now so I'll try to help but take everything I write with a grain of salt.
    First the gear: 12 gear is cheap used because everybody goes to the 18 gear when rebuilding. I left my old 12 gear with Nick Smith formerly smith Cubs , so you could give him a call for used gear. No bends in the gear are allowed. 12 gear is every bit as good as 18 gear for normal flying, it's a few knots faster than 18 gear. The draw backs are; difficult to change to floats, usually end up cutting bungees. There are mods for the 18 gear with STC's to extend 3&6" good thing for skis and long props.
    Second gas tanks: stock tanks are dangerous they need to go away. There have been several discussions about the pros and cons of the after market tanks. The simple way is the wag tanks but they have a rep of leaking. They are the cheapest and I think Mike from MCS was the one that recommended getting them and having the welds checked and repaired before installing them. The biggest thing is the lack of front outlets and fuel starvation on approaches and in turns with the right deck angles. The Dakota 24 gal and the f atlee 30 gal tanks are both good. There is also a mod STC to get rid of the header tanks and new fuel selector with L R & both. Again what range do you need and this is just from reading I'm still in the build stage. Hope this help some what.

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    txfirefighter628's Avatar
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    The plane is stock and flying right now with an O-235 and I will keep that engine and prop on it for a long time. About the only upgrades are pa-18 tail feathers and cleveland wheels and brakes. The plane will never be on floats while I own it, so I dont have to worry about that. I've read lots of bad things about stock 12 gear colapsing so I think 14 gear would be the easiest. I will probaly put 8.00x6 tires on it, nothing to big.

    I like the idea of the dakota cub tanks but I've read its alot of work to install. I dont want to tear it down and turn it into a project, maybe a week at a time down time at the most for inprovments i would do to it. I dont need any improved range, im in central Texas and airports with fuel are pretty easy to find. I will probley do the cub crafters STC to get the rid of the fuel stavation problem and have a L,R, both selector.

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    12Geezer2's Avatar
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    Get a good A&I that knows how to weld---beef up the gear you have----Walking around Oshkosh, I've seen a few of the original strap type gear still flying but most have had the streamline tubing added to give some integrity to side loading---there must be paperwork for this somewhere---12 experts speak up !!!! PLEASE

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    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by 12Geezer2 View Post
    Get a good A&I that knows how to weld---beef up the gear you have----Walking around Oshkosh, I've seen a few of the original strap type gear still flying but most have had the streamline tubing added to give some integrity to side loading---there must be paperwork for this somewhere---12 experts speak up !!!! PLEASE
    yup its easy to split and add the beef up streamlined tubing... helps for side load... not quite cub gear, but WAY better than the will fold up strap....

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    I got a set of Wag tanks for my 12 I did a simple soap and blow test on my tanks with no leaks. I had to weld in the fittings for the wing root sight gauges and the forward fuel drain I went with a Dakota Cub fuel valve and fuel system. When you weld the streamline tubing over the strap you can also add a small piece of tubing from the streamline tubing to the gear leg and that will really strengthen things up for you.

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    txfirefighter628's Avatar
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    Thanks guys, all the positive responses make me feel much better about going ahead with this purchuse. The part number for the streamline tubing in Piper service letter 109 is #11317-00. Is this part still availible somewhere or do you just have to get some streamlined stock and cut to fit?

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    TurboBeaver's Avatar
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    Interesting post, and you may have read to much into some of the "gear collapsed" story, as you have already
    Stated you have no intentions of running big tires, or long props, so there is absolutely no reason to spend
    A ton of money converting the gear over, the boys here are giving you good advise on just beef yours up,
    As far as your old tin tanks are consirned, again before I riped mine out and spend thosands of dollars converting
    Them if you will just spend 2 hrs on them with a big old fashion soldering iron, to go around every seam, so the integrity
    Of all the joins are perfect again, you can save yourself ALOT of money?Last set I did that way lasted dam near 10 years before
    I ever noticed them weaping again..... just saying. Not sure why you feel you need balanced
    Tailfeathers right away, if your not on floats or flying out of deep snow? They are nice to get your tail up quicker in the rough
    Stuff but not sure that is much of an issue flying off a paved runway?? And since your not going to be changing your gear
    Twice a year the only other advantage of 18 gear is out the door. They are a great old bird, buy it and fly it, and first "lounge
    Pilot" that walks by it and says"oh she still has the old gear on it" just smile and tell him , yes it does and still works great after
    Almost 70 years!

  9. #9
    nanook's Avatar
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    I have a problem with 70 year old tubed, enclosed, metal landing gear, What does the inside of it look like? Same question pertaining to the fuselage. Be aware of what the problems are. I hope you have a knowledgable inspector looking at it. Just because someone did something 30-40 years ago and it worked out, doesn't mean the same advice is sound now. These steel-framed structures weren't designed to remain in use for seventy years. Look at the original tin-soup-can fuel tank design....very few are still airworthy now. You end up putting expensive engines, props, avionics and precious friends and relatives in these things. Now is not the time to be a cheap bastard....
    Last edited by nanook; 03-28-2015 at 05:17 AM.

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    skywagon8a's Avatar
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    Quote Originally Posted by txfirefighter628 View Post
    ...The left gear flat steel has a slight wrinkle/curve in it. Does this totally compromise this gear or can it be repaired?
    This "flat steel has a slight wrinkle/curve in it" would prompt me to look further. I would want to know why. This is indicating to me that sometime in it's past there was an extreme side load applied to this gear. There may be some bent tubing or a hidden crack in this gear. At that time were the fuselage gear fittings compromised? Ground loop perhaps? Left wing tip damaged and repaired? Wrinkle in left spar? Left wing replaced? None of which, if properly repaired, is cause for rejecting the purchase. Maybe this gear came from another -12? I have not looked at a lot of -12 gears recently. Perhaps this is normal? Certainly is something to look closely at.

    IF this gear had a side load strong enough to still have a wrinkle in the strap it has to have had a severe enough side load which did not spring back all the way to the original shape. That is unless Piper made some in which the strap was not straight?
    N1PA

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    txfirefighter628's Avatar
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    Quote Originally Posted by skywagon8a View Post
    This "flat steel has a slight wrinkle/curve in it" would prompt me to look further. I would want to know why. This is indicating to me that sometime in it's past there was an extreme side load applied to this gear. There may be some bent tubing or a hidden crack in this gear. At that time were the fuselage gear fittings compromised? Ground loop perhaps? Left wing tip damaged and repaired? Wrinkle in left spar? Left wing replaced? None of which, if properly repaired, is cause for rejecting the purchase. Maybe this gear came from another -12? I have not looked at a lot of -12 gears recently. Perhaps this is normal? Certainly is something to look closely at.

    IF this gear had a side load strong enough to still have a wrinkle in the strap it has to have had a severe enough side load which did not spring back all the way to the original shape. That is unless Piper made some in which the strap was not straight?
    i have the exact same concerns as you about the gear. The seller claims no damage history. I wonder what caused the gear strap to get like that and did it damage any thing else, guess I'll have to wait till the pre buy is done before I'll know.

    Turbo beaver, I don't want to add PA18 tail feathers, it already has them on it., which is nice. I was trying to say the plane is stock except for pa-18 tail feathers and Cleveland wheels and brakes.

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    skywagon8a's Avatar
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    Quote Originally Posted by txfirefighter628 View Post
    ...The seller claims no damage history.
    It is very possible that the gear has been like this for years before the current owner bought it. And that nothing was ever entered into the log books. Ask the person who is doing the prebuy to check the things which I mentioned.
    N1PA

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    Steve Pierce's Avatar
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    Ron, we could add the streamline tubing. Aircraft Spruce has the tubing and I believe I have a set of gear already modified. You might give me a shout and I will go look at it with you if you'd like.
    Steve Pierce

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    Quote Originally Posted by skywagon8a View Post
    This "flat steel has a slight wrinkle/curve in it" would prompt me to look further. I would want to know why. This is indicating to me that sometime in it's past there was an extreme side load applied to this gear. There may be some bent tubing or a hidden crack in this gear. At that time were the fuselage gear fittings compromised? Ground loop perhaps? Left wing tip damaged and repaired? Wrinkle in left spar? Left wing replaced? None of which, if properly repaired, is cause for rejecting the purchase. Maybe this gear came from another -12? I have not looked at a lot of -12 gears recently. Perhaps this is normal? Certainly is something to look closely at.

    IF this gear had a side load strong enough to still have a wrinkle in the strap it has to have had a severe enough side load which did not spring back all the way to the original shape. That is unless Piper made some in which the strap was not straight?
    There is a 12 here that is mostly original. The gear looks fine until the fuselage is lifted off the floor. Then the right gear has a gentle S in the strap while the left stays straight. Apparently it has been that way for over 30 years and lots of hours as the owner never saw it off the floor since he bought it,nobody noticed it when flying, and he swears he never had a wild landing that might have bent it. I don't think it was built that way by Piper. It's due for shock cords and it will get a close look and the streamline reinforcements if the gear passes the tap and poke tests and maybe an ultrasound or Xray if they are iffy.
    As far as buying the tubing- I think Univair might sell it as the P/N but I expect an old strut will provide the same tube for much less $$$. One original fuel tank is a seeper and it will get repaired. The gauges will get cleaned up and new seals and balsa streamlines to stop the right side from vibrating in flight. jrh

    Oh, hey Mike, when you added the streamline tubing, of course it gets welded full length to the back of the strap as the slit needs closed. Question is, do you stitch weld to the front of the strap through the tube or leave it not welded?

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    skywagon8a's Avatar
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    Quote Originally Posted by N86250 View Post
    ...Oh, hey Mike, when you added the streamline tubing, of course it gets welded full length to the back of the strap as the slit needs closed. Question is, do you stitch weld to the front of the strap through the tube or leave it not welded?
    This is Piper SL109 from http://www.univair.com/piper-pa-12-and-pa-14-index/.

    https://store-dtwuls.mybigcommerce.c...PIP_SL0109.pdf

    Looks like the streamline tube has more chord than the width of the strap.

    It is very possible that the slight curve in the strap has been there from the very beginning. Welding does funny things to structures such as minor distortions.
    N1PA

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    Quote Originally Posted by skywagon8a View Post
    This is Piper SL109 from http://www.univair.com/piper-pa-12-and-pa-14-index/.

    https://store-dtwuls.mybigcommerce.c...PIP_SL0109.pdf

    Looks like the streamline tube has more chord than the width of the strap.

    It is very possible that the slight curve in the strap has been there from the very beginning. Welding does funny things to structures such as minor distortions.
    Thank you skywagon. I have that drawing and found it a bit confusing. Section A-A shows the streamline tube attached at the front. Maybe should split the tube at the leading edge? I guess I assumed splitting would be at the trailing edge. I was guessing the drawing was perhaps not done perfectly to scale, and actually I expected to go through old struts until I found one that fit the strap closely front and back. Maybe a rear strut from? Maybe drawing SK-198 refered to in the SL would make it more clear. Or a drawing for p/n 11317 . jrh
    You can't get there from here. You have to go over yonder and start from there.

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    texas fire fighter, the 12 I have been flying for 19 years came with original tanks, old lift struts and original gear with the sleeve welded over the strap. When I recovered the plane 4 years ago I replaced an original tank with a Wagaero tank, the original still wasn't leaking after 70 years, I just did it on principal. I leak tested the wagaero tank before install and it was well built and didn't leak. I did weld in wing root site gauges to eliminate the down tube guage but that's all. Don't worry about the tank until it starts leaking then either replace it with a wag one or solder up the leak. I am putting the Dakota 24 gallon tanks in my current project but only because the wings were already torn down. One nice thing about that smaller engine is the rate at which it sips the fuel, standard tanks will serve you well.

    I've never had a gear issue or concern, as some on this site have said: Mr Piper got a lot right when he built these things 70 years ago.

    The new sealed struts just bolt right on where the old ones came off. Again I upgraded at recover but mostly on principle. My old ones always tested fine, but decided what the heck, while I'm at it....by the way the annual punch test of the lift struts took me about an hour or two under the supervision of my IA. The Atlee struts if I understand it right are sealed but something got lost in the paper mill process and still require some sort of testing, again hardly worth $2200 to replace a perfectly good item.

    I recommend you do what I did 19 years ago, buy it and fly the heck out of it and work on small things as time goes by. You'll never regret it.

  18. #18
    cruiser's Avatar
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    The key to successfully soldering the tanks is finding the correct temperature for the iron, which is trial and error, and using a good flux. I used a product called "Stay Clean" and had no issues. You might take a detailed look at the tanks and see what has been done to them in the past, a previous goop job may be the biggest obstacle to a successful solder repair.
    Last edited by cruiser; 03-28-2015 at 11:15 AM. Reason: Correct spelling

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    skywagon8a's Avatar
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    Quote Originally Posted by N86250 View Post
    Section A-A shows the streamline tube attached at the front. Maybe should split the tube at the leading edge? I guess I assumed splitting would be at the trailing edge.
    Look on the drawing just above the A-A view. It says to "weld trailing edge after installation". The streamline tube is not welded to the strap at all. Actually it is likely that when welding the trailing edge, shrinkage in the weld will curve the streamline tube. Thus it it a good idea not to weld it to the strap.
    N1PA

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    Been flying my 12 for about 15 years now and not had any problems until recently with a tank seeping around the gauge. Lot of discussion here condeming the tanks for some very valid reasons. Still I feel anything that has worked for 68 years without a problem has to have some merit. My fuel gauge appears to have bonked someone in the head or something as it is bent back about 15 degrees and I suspect the leakage is due to the damage incurred by the impact. Will be removing and repairing shortly. Flying partner is installing Dakota tanks in his 12 project, but I think you would only consider that as he is, on a complete rebuild with the cover off. Appears to be a signficant amount of work to install.

    Replaced my stock gear with 18 - 3" extended only because an impact with something on the ice kinked the reinforcing tubing over the flat strap. I think the flat strap was one of the biggest blunders of design Piper made on the 12. Seems to me a junior engineer would have anticipated side loads that would contribute buckling of that component in the lamest of bad landings. I agree with a lot of the comments above about old tubing and how long can they possibly last, but I think a good inspection goes along ways and when there are opportunities for improvement such as new 18 gear it helps to mitigate some of the questionable components integrity by biting the bullet and replacing. Guess that is my 2c.

    Otherwise provide you get a good prebuy inspection and report you will have a lot of fun with a Great Airplane. Good Luck!!!........Rod

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    Quote Originally Posted by skywagon8a View Post
    Look on the drawing just above the A-A view. It says to "weld trailing edge after installation". The streamline tube is not welded to the strap at all. Actually it is likely that when welding the trailing edge, shrinkage in the weld will curve the streamline tube. Thus it it a good idea not to weld it to the strap.
    I was looking so hard for what I wanted to see that I missed what I should have seen. Thank you for pointing it out. All necessary info is right there. Thank you. jrh
    You can't get there from here. You have to go over yonder and start from there.

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    skywagon8a's Avatar
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    Quote Originally Posted by N86250 View Post
    I was looking so hard for what I wanted to see that I missed what I should have seen. Thank you for pointing it out. All necessary info is right there. Thank you. jrh
    That's OK, I missed it too, until you prompted me to look again. My first thought was that the strap was welded to the leading edge cut.
    N1PA

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    txfirefighter628's Avatar
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    Thanks again for all the great info, this thread has a lot more positive things to say about the stock gear and fuel tanks then any of the previous threads that I have searched. Unless I find major damage to the fuselage or wings during the pre buy I think it will be a good deal. The plane I'm looking at is set up for a banner/glider tow hook. If the plane was used for this is there any damage or extra stress points to look for on the fuselage?

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    FWIW, I'd recommend replacing tanks and using 18 gear "just because". I like the 18 gear a lot better than the -12 gear but made a bunch of hard landings on the 12 gear without collapse.....at a minimum would recommend doing the beefup on the gear.

    If memory serves, and it is serving less as I age, there were 3 items that almost rendered my -12 un-airworthy at the initial pre-buy: 1) substantial rust at the tail cluster; 2) more corrosion than I liked at tube connection points near the (right? left?) rear window; and 3) a tailwheel attach bolt that was withing 1/8" of being sheared off. Maybe an Alaska (vs. Texas) thing, but I'd really look closely at the tail cluster of tubes.

    All FWIW.
    Back In Alaska

  25. #25
    TurboBeaver's Avatar
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    Just wondering 12drvr.
    Besides changing the gear????,[which can actually be done in less than a half hour without any special tool whatso ever] what is the thing about 18 gear that you like "a lot better". Assuming you had no problem with the 12 not being rugged enough , as you said , it must have to do with hyrosorbs vs having the bungee on the end of the legs ?????? Assuming one has new bungees on his 12 gear and has no intentions of running big tires or landing a lot in off airport environments , what is so much better for someone like him ???? Having flown PA-12 for years both ways , for normal airport flying I found the standard gear to work very well ???? I liked 18 gear that is "extended" to get more AOA on skiis but found it is certainly slower, And I thought that beefed up 12 gear will take a lot of abuse, So just curious what the "just because" is really coming from???? As if a guy is going to pony up for say $3K to swap it out, he better have a really good reason, and since he isn't flying into rock piles on monster tires, why would he need to do that conversion??? Interesting thread with the different points of view , like if you don't care for 70 year old tubing , what is the fix for that ? Buy a whole new 4130 airframe ? Why change the gear legs, if the fuselarge is going to cave in at the attach points , where do you stop ??? Same with the tanks, do you just throw another $3/4K into fancy tanks, that you probably don't even need, when a few hours with a soldering iron could get you by for many more years???
    I am fully aware that NEW stuff is nice, and some of this thinking is how folks get $150,000 into a Piper Cub as if you want everything brand new that's about where it winds up if you have it all done by someone else.
    Are the day of a guys buying an old PA12 and just beefin the gear up and soldering his tanks up and just flying the heck outta it, having fun and not worrying about trying to pretend he is in Alaska Bush Flying, really gone????, Say your selling the plane in a few years will it really bring the extra $$8 grand you have dumped into it, with no flaps and the small engine???? I sorta doubt that....................

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    mvivion's Avatar
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    Turbo,

    I mostly agree with you on the gear. The tanks, not so much. While those tanks MAY hold gas just fine for many years, if and when they DO leak, they are a major PITA to fix right. Your comment "a few hours with a soldering iron could get you by for many more years" might be true if you get really lucky, and the person doing the soldering really knows what he's doing. But, the down side is, to do that, you have to remove the tanks, which means draining them, then you have to flush them, get all the gas out, etc, etc. Then you have to PROPERLY solder them, which isn't quite as easy or simple as you suggest. In my case, one done by a very well known and expert mechanic leaked almost immediately after the repair.....not in the same spot, mind you......the (very careful) removal and handling and re-installation of the tank created another leak. So, drain the tank, clean it and purge it, solder the whole damn thing.....and there's a LOT of seams there.....etc.

    I wouldn't wish a set of those old terne plate tanks on anyone, frankly. Maybe I just wasn't that lucky.

    MTV

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    Turbo and MTV; like I said, how about the best of both worlds: Fly the old tanks till they leak then pull them out and replace them with new Wagaero, al tanks. That's what I did and it worked great, only got 66 years out of one of the original tanks tho. 4 years so far on the new tank and it too is working great. see post #17.

    This guy appears to be trying to get into flying a pa-12 for a decent price with what seem to me to be a realistic view of what his flying will be like.

    txfirefighter: I saw what I assume was the plane you were looking at on one of the web for sale sites with an 'offer pending' sticker on it. Did you get it? Hope so...

    doug

  28. #28
    180Marty's Avatar
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    There is one thing that I remember about the old original terne tanks that Jim Soares did. He had a punch press that he made stainless slugs about the size of a quarter. In each bay of the tank he drilled a hole through top and bottom of the tank and the slug too. Welding rod was inserted from top to bottom and bent flat on each stainless slug and then soldered. Doing this connected the top with the bottom and stopped the tin canning that caused the cracking.

  29. #29
    12Geezer2's Avatar
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    Kind of agree with MTV on the fuel tank thing. Have a good friend who did a nice rebuild only to have UGLY fuel stain all the way down the fresh fuselage fabric.--only a month or so after rebuild. Kind of agree with turbo on the gear thing. My 12 was a budget rebuild mostly done by me, the owner, under the watchful eye of a couple good A&Is . Have original gear with original style brakes and those expensive little 4x8 Cub tires. Have had more off airport fun than any old geezer should be allowed. NO --I can't land in all those places those fat (expensive) tire guys can--but I really don't have to---I only fly for fun---not interested in competing in all the extremes. Had a fun day just yesterday letting a Citation Pilot have a little tail wheel fun. Says he hasn't flown tail wheel in more than 20 years. I was happy to see he had not forgotten how. He was not fond of my old fashioned heel operated brakes. I was taught by a good Super Cub guy who said you need to NOT rely on brakes too much with the old stock stuff. Do your best to plan ahead so heavy braking is not needed. So Far So Good---HOWEVER I know if I let my guard down I could wad it all up tomorrow. Know your airplane and it's limitations and most of all know your own limitations and don't fly too close to the "edge". just my 2 cents---geezer Dan

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    Pulled my tank I referenced above last week and dropped it on the door step of my IA yesterday morning. It definately had been leaking for some time around the bung that houses the sight gauge. And it appeared the solder joint had seperated from the tank from banging on the bung. My research on Terneplate led me to believe it was some kind of lead plated steel tank. Oddly enough a magnet would not stick so I thought it might be aluminum. However a stamp on the top of the tank had a serial number and build date of January 10 1947 by the Kaiser Cargo Corporation of Bristol PA. Obviously it was original. My IA researched and discovered it was actually fabricated from roofing material of the day that being tin-coated copper. That explains the non magnetic. Anyhow after flushing the tank with hot water and evacuating with a vacumn for an hour he proceeded to resolder with a small flamed torch and had it repaired in no time.Even though it leaked checked ok I will keep my fingers crossed that no new leaks like MTV talks about begin to happen. I guess I am comfortable with the time I have spent and the less than $200 bill from my mechanic to have gone the route I have chosen. Time will tell. Seems like there can be problems either way. My flying partner has a brand new set in the box Wag Aero tanks circa 1960 perhaps (no paperwork) that I could have used but my course seemed to be the path of least resisitance and dollars. Agree with TurboBeaver, MT12 and Dan above. I am in the collision business and I see it all the time that people would like to throw away older things that are either damaged or with issues but in the real world that doesn't happen for most folks. And that is not all bad!..........Rod

  31. #31
    TurboBeaver's Avatar
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    Well looks like we are pretty much getting to the bottom of this, mtv: sorry you had bad luck with your tanks, however I have been mixed up
    In half a dozen of these tank solder jobs and had exactly the opposite results you did, Cruiser has described the procedure correctly and of course pulling the tanks is a job in it self that has to be done regardless of how you are going to fix leaking tanks, so I wasnt counting that. When I did the last set I compleatly resoldered both tanks and added sight gauge fittings easily in a mornings work ,taking my time to release ALL the old joints and resealed ALL of them, so I gotta stick with my story here, on an old fixer upper type cruiser I would solder em up everytime!
    Marty your buddys fix sounds like cool way to solve that problem! Badmdcn that is the best explaination of the actual construction of the old tin tanks I have ever heard, great research there!
    So on it goes we all have different experences and had i have had the same results as Mike has, I would probably be singing a different tune! MT you hit the nail squarely on the head.........

  32. #32

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    Quote Originally Posted by TurboBeaver View Post
    Just wondering 12drvr.
    Besides changing the gear????,[which can actually be done in less than a half hour without any special tool whatso ever] what is the thing about 18 gear that you like "a lot better". Assuming you had no problem with the 12 not being rugged enough , as you said , it must have to do with hyrosorbs vs having the bungee on the end of the legs ?????? Assuming one has new bungees on his 12 gear and has no intentions of running big tires or landing a lot in off airport environments , what is so much better for someone like him ???? Having flown PA-12 for years both ways , for normal airport flying I found the standard gear to work very well ???? I liked 18 gear that is "extended" to get more AOA on skiis but found it is certainly slower, And I thought that beefed up 12 gear will take a lot of abuse, So just curious what the "just because" is really coming from???? As if a guy is going to pony up for say $3K to swap it out, he better have a really good reason, and since he isn't flying into rock piles on monster tires, why would he need to do that conversion??? Interesting thread with the different points of view , like if you don't care for 70 year old tubing , what is the fix for that ? Buy a whole new 4130 airframe ? Why change the gear legs, if the fuselarge is going to cave in at the attach points , where do you stop ??? Same with the tanks, do you just throw another $3/4K into fancy tanks, that you probably don't even need, when a few hours with a soldering iron could get you by for many more years???
    I am fully aware that NEW stuff is nice, and some of this thinking is how folks get $150,000 into a Piper Cub as if you want everything brand new that's about where it winds up if you have it all done by someone else.
    Are the day of a guys buying an old PA12 and just beefin the gear up and soldering his tanks up and just flying the heck outta it, having fun and not worrying about trying to pretend he is in Alaska Bush Flying, really gone????, Say your selling the plane in a few years will it really bring the extra $$8 grand you have dumped into it, with no flaps and the small engine???? I sorta doubt that....................
    I guess this is directed at me....and I don't need to defend my FWIW opinion...so I won't.

    What I'd offer is the following:

    - I spend far too much time in Ewe-stun and get out to central Texas quite a bit...almost exclusively on 4 wheels, infrequently on 2, and even less frequently on 3
    - There's a multitude of airports in central Texas that (at least between October and May when it's not beastly hot) make it the perfect place for the inflation adjusted $150/hamburger...
    - ...and a stock or near stock -12 is darn near the perfect putter-arounder and fun to fly airplane that can be got into for a pretty low price I bought mine for less than $20k back in the day.
    - But there are lots of fields, draws, islands, creek beds, and hilltops in the area as well that (with some investigation of land ownership) might be fun to explore and land upon....meaning something besides stock gear/tires might be slightly beneficial.
    - I liked the -18 gear for the AOSS that I put on mine and for the safety cables and for the extra 3". I saw no sense in keeping stock tanks when I rebuilt the -12 so I put new ones in. If the stock aren't leaking (I'd want to look very closely before reaching that conclusion), by all means, leave the stock tanks in.

    txfirefighter asked questions: there have been knowledgeable replies. I offer FWIW opinion which txfirefighter is free to ignore ...and on general principles (given that Texas is only 2 hours away from Houston), he probably should ignore the opinion of someone stuck in Ewe-stun.
    Back In Alaska

  33. #33

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    I have made a few posts over the years about the PA-12 fuel tanks.
    The original tanks were made of a thin and brittle material I think called turn plate. In an attempt to make the tanks stronger Piper put three span wise channel ridges in both the bottom and top of the tank. These bottom channels tend to block water from flowing aft in the tanks. The incidence angle of the wings cause the water if there is any to run toward the aft end of the tank and wing. The dihedral angle causes the water to run inboard toward the wing root. These ridges or channels will prevent some water from reaching the aft end of the tank. A bank in flight allows the water to pass the channels and reach the fuel pick up. There is also about three and a half inches aft of the quick drain where fuel can sit and not be drained when sumping the aircraft. Making matters worse is that the 12 tanks have no sump. They do have a quick drain but it is located in the flat bottom of a flimsy tank. After years of pushing up on the quick drain against the spring pressure the tank bottom oil cans upward and any water in the fuel sits in a circle around the quick drain which is oil canned higher than the surrounding area. It can leave un-drainable water in the tank. For those of you who think that your loving aircraft never makes water, the fact of the matter is that when the right conditions exist, all of them will make water and often more than you expect.


    To complicate the issue is the service bulletin which requires a gasket around the filler neck to keep fuel overspills from getting into the wing and making a potential volatile situation. Good idea except that it also traps water against the filler neck and if your 12 like most aircraft has had a funnel with a fuel can on it or a high volume fuel hose hanging on it, it probably has cracks at the base where this water pools inside that gasket.


    Most of the Cubs and other high wing aircraft also get the water to the root end of the wing so it can be drained by the angle of dihedral. Especially with flat dihedral wings like the cubs a bungee stretched while turning to park or a little depression or uneven ground will leave the water in a tank flowing to the outboard side of the tank and not available to drain.


    The 12’s while a wonderful plane, I had mine for over 40 years and drove it through the trees because of an engine failure on takeoff due to water in the fuel after having drained all my sumps twice getting clean fuel on all quick drains on both sumpings. Significant time was spent not only on the rebuild but on figuring out what caused the issue and how to prevent it from happening again. The 12 has a very high accident rate resulting from water in the fuel.

    After showing NTSB and the FAA what I had found I was not charged with a pilot error accident but no SB or AD note was made. A
    SB or an AD should have been made years ago when the FAA, NTSB and Piper were advised of these issues.

    The 12 tank is unsafe and should be replace by any means possible.There are other tanks available and regardless of cost, legality or paperwork they should be replaced. I chose to put a sump and boss for a quick drain on the outboard side of the tank as well as the inboard side. This way water can be drained regardless of the rotational attitude of the plane. This rotation of the aircraft around the nose to tail orientation is even more critical one one thinks about the aircraft on floats and the fact that if your standing on the float it is pushed down in the water and the opposite wing is high and the wing on the side you are standing on is low and may have water which would be undeniable since the water would be at the low end of the tank at the outboard end.

    Since an 18 is taken off from the left tank, one can stand on the right side of the aircraft and reach through the aircraft and drain the left wing to get a good drain. With an inboard and outboard drain on each tank, they can be sumped regardless of attitude. A 12 in original configuration cant be drained successfully while standing on a float.



    A quick note about the gear. Cable is great when you want to pull something but its very hard to push something with it. A 12 with the original gear having a flat strap may be nice and original but it is not capable of taking any side loads. The flat strap is fine in tension but it is not so fine when it comes to compression. Perhaps to keep it original one might want to have the flat gear but if your 12 ever has a side load your risking the whole ball game. The splitting a piece of streamline tubing and welding it over the flat strap is fine. So is cub gear.
    Last edited by reliableflyer; 04-12-2015 at 09:59 AM.

  34. #34
    TurboBeaver's Avatar
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    Wow!

  35. #35
    mvivion's Avatar
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    Quote Originally Posted by 12Geezer2 View Post
    Get a good A&I that knows how to weld---beef up the gear you have----Walking around Oshkosh, I've seen a few of the original strap type gear still flying but most have had the streamline tubing added to give some integrity to side loading---there must be paperwork for this somewhere---12 experts speak up !!!! PLEASE
    Was just roaming around through Service Letters and found this one: https://store-dtwuls.mybigcommerce.c...PIP_SL0109.pdf

    Not sure if this constitutes a basis for the modification, but at least it tells you how to go about it.

    MTV

  36. #36
    Gordon Misch's Avatar
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    I thought covering the flat strap with streamline is an AD? But maybe it's just a service bulletin?
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)

  37. #37
    txfirefighter628's Avatar
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    Thanks for all the info. I ended up buying a different PA-12 then the one I originally asked about due to the wealth of information given from the members of this site. It has the streamlined gear service letter done, which is not an AD. It has 1 new wag aero fuel tank and one stock. It has Univair sealed struts. Now I just want to change the stripe color to red/black and put in a new interior in some time down the road. It's a good flier now, picked it up in Michigan and took it home to Texas.
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  38. #38
    mvivion's Avatar
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    Yahoooooo! Congrats!

    MTV

  39. #39
    Bill Rusk's Avatar
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    Congrats. Let the games begin.

    Bill
    Very Blessed.

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    Just a follow up to this post: The tanks on my -12 are also stamped "Kaiser" and, if I remember correctly, were labled "Fleetwings Division". Fleetwings specialised in spot welded stainlees steel and were the makers of the Fleetwings Sea Bird, a single engine amphib. with a stainless steel spot welded fuselage. Fleetwings was, as some point, located in Bristol, PA.

    The tanks in my -12 are stainless steel and are non-magnetic. Terne plate is a lead coated mild steel commonly used for fuel tanks and would be magnetic. The tanks are spot welded with the seams sealed with solder. Like most of these tanks, mine were leaking and I resoldered them back in the '70's. The leaks were at the very corners of the tank at the supporting front and rear flanges. A flux suitable for stainless must be used. The repair has held up so far but keep in mind that I don't fly out of rough strips or on floats.

    I haven't seen enough tanks to know whether PA-12's had just stainless tanks or some stainless and some terne plate tanks. A magnet will easily identify which is which.

    The Fleetwing's tanks are light and it would be interesting to know the weight difference between them and the alum. replacement tanks. Everything is a compromise and, in this case a matter of weight vs. durability.

    A word to the wise: The fuel pick-up from these tanks is in the rear inboard corner and the "usable fuel" is highly dependent on the attitude of the airplane. Fuel can be feeding in cruise on a low tank but when you pitch down for descent the fuel will run towards the tank front and unport. I was warned about this but many years later had to go out prove it inadvertantly for myself. My -12 was a later version without the header tank system.

    Have fun with your PA-12.

    COFlyer

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