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

[TurboBeaver]

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.........

 

[pa12drvr]

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. :lol:

 

[reliableflyer]

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.

 

[TurboBeaver]

Wow!

 

[mvivion]

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.com/content/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

 

[Gordon Misch]

I thought covering the flat strap with streamline is an AD? But maybe it's just a service bulletin?

 

[txfirefighter628]

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.

 

[mvivion]

Yahoooooo! Congrats!

MTV

 

[Bill Rusk]

Congrats. Let the games begin.

Bill

 

[COFlyer]

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

 

[skywagon8a]

Here's another example of a stainless steel seaplane built in Pennsylvania. It was mounted on a pedestal in front of the Franklin Institute in Philadelphia for years.

 

[reliableflyer]

The five PA 12 tanks I used during my tests after my water in fuel related accident 30 some odd years ago were all non magnetic, and soldered . My assumption at the time was that they were turne plate but I don't know for sure. They appeared to be silver soldered. All were very flimsy and had the span wise ridges and no sump. A boss for the quick drain was soldered in the aft inboard end of each tank. All were oil canned up around that quick drain boss making the water which I placed in the tanks lie in a circle around the raised area surrounding the quick drain boss. All the 5 test tanks had been blocked to the incidence and dihedral angles which I found by checking numerous PA 12's with a bubble protractor. This water was not available to be drained because of the raised area around the quick drain unless of course the volume of water was considerable. This oil canning appeared to result from years of pressing the quick drain up and therefore pushing against the bottom of the tank at the quick drain and then being returned to the closed position by the spring in the quick drain.

Another significant issue is that if the angle of the aircraft around the nose to tail rotation is greater than the dihedral angle then water in the low tank flows away from the quick drain towards the outboard side of the tank and is not available to be drained. It does not take much rotation to pass the dihedral angle. My calculations at the time showed one axel at (0.62) inches above the other, passes the angle required to have the fuel drain to the outboard side of the lower tank. On floats when one stands on the float to drain the quick drain the float and therefore the aircraft is always pushed down into the water causing the water to flow to the outboard side of the tank.

Some 12's had a header tank forward of the fuel valve by the pilots left knee. All others would be subject to being ported during decent in a low fuel condition.

This was all shown to the NTSB some 30 years ago yet they failed to recommend any corrective action. The FAA was also advise and they also failed to take any corrective action. Even Piper was advised and chose not to act.

At at this point in time when I go to my GADO office to talk with someone I must talk to a receptionist through a remote speaker. Not my idea of a satisfactory working relationship between the FAA and the public.

in my opinion the original tanks are unsafe and should be replaced. There are legal options.

Some of the same issues (low dihedral) which has many advantages, found on other aircraft such as the PA-18 increase likelihood of being unable to adequately be able to drain water from them fuel