Sealing the fuselage tubing against internal corrosion (merged)

[Guest]

Bill,
I have owned several t-craft's in the past and had to replace several struts due to rust in the lower 3-12 inchs(primarily in the rear struts of pre-war birds,but some post war too). A couple of them would have never been noticed had I not took the time to punch around on them with an awle(punch/ice pick).The paint looked great but with just a little lite pressure with a sharp object there was a hole were a hole should not be!

Here is my 2 cents worth on everything.....The people who have good original struts that have been careed for properly over the years and hangered most of the time have all the reason in the word to question this AD,or at least some of the testing methods.However they too could be fooled upon inspection therefore once they have them inspected and find nothing wrong then they will be even more upset,BUT,for those who think there struts are fine then find a problem during the inspection are going to be greatful and maybe at least one or two lives saved in the future(that's worth the cost and aggervation to me).

The Piper guys lost a few people before they got an AD....do we want to wait until our planes start falling out of the sky due to a tight wallet or just being stubbern? Some of our birds(no all and not many) have a problem in this area so lets check them all and be safe.

About the Dave Wiley bird,it was a pre-war airplane with lighter steel tubing used to make the fuslage and all ajoinning fittings. The pre-war birds are a little more subject to have rust or cracks around the gear and strut fittings on the fuslage,especially one that has spent the best part of the last 30 years on floats and used for flight training. So here you have a bird that hadn't been apart in many years,spent 90% of it's time outside on the water flying almost daily doing(forgive me if I am wrong about this part) float training which is a little abusive to an airframe to say the least. I have owned one pre-war project that I flew home and after disassembly I found that it had a moderate amount of rust around the strut fittings and the lower longerons. I have had several post war birds and have seen rust problems in almost every place except the strut fittings. I don't think the strut fittings need an AD on the post war airplanes...not yet anyway.

Bill,I didin't mean to direct this at you but it seemed like a good quote to reply too. You ask for proof and I have at least 8 rusty struts in the top of my hanger.If you would like to see them I will try to get some pics sometime next week when I get caught up a little bit.

In short, I think the strut AD is a good thing based on what I have seen in the past. I think you'll find the outside birds,coastal birds,float birds, and pre-war birds are going to be more subject to the good of the AD. As for the possiblity of a strut fitting or longeron AD.I think it should be subject to only those with the lighter steel tubing(pre-war birds) or float equipped birds for now.

As for the guy with the vented tail post.....watch it closely,if it doesn't have rust somewhere in it then it will have eventually unless the airplane has been in Arizona or New Mexico all it's life. Most or all of the t-crafts had a hole in the tail post but was always sealed with a rivit or some type of something to seal it unless it was a factory seaplane(Forrest,please correct me if I'm wrong but I think I'm correct). I think they left it open on the seaplane incase water managed to find a way in.

Now about all the fuss over buying or inspecting. If I was comfortable in thinking my struts were still fine then by all means save money and have them inspected. For those of you who are not sure and you elect to have them inspected remember if you have one,two,three,or all four fail then you will not only have to pay for the inspection and all labor assotiated with it but you will also have to pay for struts too. So,when you have them inspected make sure you are also aware that they might not pass.

As for the Univair verses Factory....most know that I was disappointed once by the factory but at least now they are trying to make parts and no payment until you get what you ordered. There struts priced seperatly are compatible with Univairs price as well. Just remember if you just buy the struts then you will have to make or buy new jury strut clamps also because all the new strut reguardless of who you buy them from are a larger diameter then the originals. As for everyone blaming the factory for this AD....maybe they started the wheels in motion but the FAA has been investigating it for the last couple of years or longer and if they didn't find any reasons for the AD then I'm sure we would not have it now.

I'm not defending or putting down the factory at this time but simply stating that everyone who has ordered anything from them in the last few months have got there parts and nobody has been stiffed! I was shocked about two weeks ago when my father(why him,his number is listed,mine is not) had a message for me on his answering machine from Harry Ingram himself. He had read my post on this forum about Crispy and what I had said about needing a factory jig if I wanted to repair my badly damaged fuslage and offered to let me use the factory jig for FREE!!!!!! . I tried to call the factory number twice but did not get an answer..just a machine and I didn't leave a message. Right now I'm am considering two other options; one is a complete fuslage from a straight project with no papers but haven't gotten a definate answer from the owner yet on price.The second is a good forward section that has a rusty tail section but I haven't looked at it yet. If niether of these work out then I will try a little harder to get up with Harry on his offer and see what the details are.

Now,if you want to buy new struts and don't trust the factory then call Univair. My advice is if the factory has them at a compatable price then give them a try...they will accept COD so you risk nothing but a little extra time if they don't come threw for ya. Plus,as I stated before, they haven't stiffed anyone in a while,they are trying, they accept COD, and if they can get it together and make it work then we will have unlimited new parts. Ya never know,if they can get back on thier feet, then the people who lost parts or money might be able to get it back.

Hi Kevin,

I have the tailpost vent (at the bottom rear). I've owned this plane in NY for 25 years (1982-2007).

Ironically the only period of time where I actually had longeron corrosion issues was during the period from 1984 to 1991 (approx) when I had mistakenly covered the hole with fabric back in 84. It was ok on 84 and bad in 91.

I believe that the vent hole is very helpful because of that experience.

I keep it clean and uncovered now.

My thinking about water and moisture is that you cannot stop it from getting but you must provide a way to get it out.

btw- I assume it will get into the top of the tailpost thru bolt holes and so on at the fin attach, that's just an assumption


Dave

[crispy critter]

Re: Price and availability of wing lift struts

If it gets into the longerons or anything thru the vertical attach fittings then it is a factory seaplane where all the tubes are welded so that moisture can flow out threw evert tube. If it is not a factory seaplane then it can't go any farther then the tail post and can't not pass into the longerons or cross bracing.

As for the hole in the tail post,if you left the hole open the I will assume you either drained all the preservation oil out of the fuslage or did not use any. In either case there is no oil in it and/or no way to let moisture out because the hole was cover with fabric. Now,even with fabric over that hole so water can not escape,that same cover hole will still let humidity in therefore causing a way for moisture to form. If the fuslage was properly treated internally,then sealed with a spot weld or a drive in rivit that will seal tightly enough to seal the holes properly then the corrosion should not have ever been a problem. On another not,if you or anyone else ever has a corrosion problem on certian sections of tubing in bird that has been properly treated and sealed during a rebuild then it is possible that a weld joint has a pin hole around it or a tube has a crack in it somewhere around or near the corroded area letting moisture in and the protective oil out.

[Guest]

Re: Price and availability of wing lift struts

If it gets into the longerons or anything thru the vertical attach fittings then it is a factory seaplane where all the tubes are welded so that moisture can flow out threw evert tube. If it is not a factory seaplane then it can't go any farther then the tail post and can't not pass into the longerons or cross bracing.

As for the hole in the tail post,if you left the hole open the I will assume you either drained all the preservation oil out of the fuslage or did not use any. In either case there is no oil in it and/or no way to let moisture out because the hole was cover with fabric. Now,even with fabric over that hole so water can not escape,that same cover hole will still let humidity in therefore causing a way for moisture to form. If the fuslage was properly treated internally,then sealed with a spot weld or a drive in rivit that will seal tightly enough to seal the holes properly then the corrosion should not have ever been a problem. On another not,if you or anyone else ever has a corrosion problem on certian sections of tubing in bird that has been properly treated and sealed during a rebuild then it is possible that a weld joint has a pin hole around it or a tube has a crack in it somewhere around or near the corroded area letting moisture in and the protective oil out.

Interesting, thanks, I used that tube oil from Poly-Fiber or Stits as I recall and they specify squirt so many cc's per foot of tube in then rotate the frame every so many hours and so on. But there is no draining involved.

I don't recall for sure but probably I would have taped the hole closed when I did it.

Maybe it is a seaplane fuselage based on what you say.

Thanks, Dave

[crispy critter]

Re: Price and availability of wing lift struts

If it was a standard fuslage(not seaplane) then you would not have got very much of the oil in the fuslage thru the small hole in the tail post. A standard fuslage would need holes drilled in the longerone at one end or the other to fill the tubes and the seaplane fuslage should accept quite a bit of oil thru the drain hole as it flows thru the entirity of the fuslage tubing.

[tawadc95]

Re: Price and availability of wing lift struts

Kevin,
You said what I was trying to say yesterday but much more precise and eloquent.....especially these two items
Why wait for planes to start falling and where there is a hole there will be moisture.
Chris

[crispy critter]

Re: Price and availability of wing lift struts

Kevin,
You said what I was trying to say yesterday but much more precise and eloquent.....especially these two items
Why wait for planes to start falling and where there is a hole there will be moisture.
Chris

.....and where there is moisture,eventually there will be rust.

[Forrest Barber]

Re: Price and availability of wing lift struts

This has all been discussed before on the previous threads. AT the old Factory in Alliance, both of them.
A "seaplane" had special treatment if manufacturered as such. During welding each intersection had a hole "popped" through by the welder so each tube was accessible if a solution like hot linseed oil ( Lionoil) was poured down the tail post, I still do it and you can feel the heat going into each tube that gets solution into it , we use about four people. put the nose down and tail on a horse and pour away. Then a cork if used to seal the tail post, the weep holes are sealed at the bottom. & you ahve a treated fuselage.
IF one of thse special fuselages is damaged and welded again then the integrity is lost. Are you all aware of the Aerobatic ships that are sealed and have nitrogen injected into the tubing with a pressure guage showing if a crack develops??? The seaplanes at the factory ahd special precautions done after welding and prior to zinc chromate too, they had a bath in another preservative ( oakite (sp) ) I really have to get back to this AD & SB problem , YES I am in direct contact with the NTSB, FAA, Harry Ingram, and NDT services. bye

[Guest]

Re: Sealing the fuselage against internal tube corrosion

According to service bulliten 78-001 the fuselage vent should not be plugged but rather be kept clean on all F19 planes. I suppose that makes it good for other models too doesn't it?

Also notice the cabane strut vent that should be added to what we might call a sealed cabane/tie strut.

Other drain/vents are mentioned too.

Venting seems to be a good a practice according to this bulletin.

[Robert Lees]

Re: Sealing the fuselage against internal tube corrosion

SB78-001
Page 1
Page 2

does not mention any hole in the fuselage tubing. It mentions "Fuselage Drain" which refers to a drain in the belly fabric adjacent to the tail leaf springs.

[Guest]

Re: Sealing the fuselage against internal tube corrosion

SB78-001
Page 1
Page 2

does not mention any hole in the fuselage tubing. It mentions "Fuselage Drain" which refers to a drain in the belly fabric adjacent to the tail leaf springs.

Interesting- mine has a vent in the metal at the bottom of the tail post directly above the tailspring. So when I read page 2 item #1 I think it refers to that drain in the metal.

But it does not say specifically that it is a hole in the fabric or in the metal.

Items 6 and 9 refer to metal vents, most others appear to refer to fabric vents.

Leaves some ambiguity to item #1 especially since both a metal hole and fabric hole exist in the area described.

Hmm

[Guest]

Re: Sealing the fuselage against internal tube corrosion

Robert-

LOL

now I am perplexed!

The metal drain hole is about 1/4" above the tailspring and at the aft most fuselage position.

The fabric hole is in plane with the tail spring top and forward of the tail post.

So your interpretation fits more nearly the "at bottom" description for item #1 and mine more nearly fits the "aft" description!

Thanks for the references and the new thread, Dave

[Guest]

Re: Price and availability of wing lift struts

Forrest,

I don't follow why anyone would create a weep hole at the factory then seal it at the factory when they plan to pour the oil down the tailpost.

So bottom line tell me this, are saying that the vent hole at the bottom of the tailpost "1/4" above the tailspring should be open or closed?

Thanks, Dave.

[Winston L.]

Re: Price and availability of wing lift struts

The hole in the bottom of the tailpost is open to the longerons. When it is welded you can't see the holes they are to give a passage way for the oil to flow down the tailpost and into the longerons etc.

Is this correct Forrest?

[Guest]

Re: Price and availability of wing lift struts

Winston, thanks but I am not following this part;

"When it is welded you can't see the holes they are to give a passage way for the oil to flow down the tailpost and into the longerons etc."

Does "it" refer to the fuselage or the hole in the bottom of the tailpost?

Do you have this drain hole at the tail post bottom like I do?

Dave

[n6346m]

Re: Sealing the fuselage against internal tube corrosion

When I did an extensive rebuild of my Stinson Floatplane a few years ago, I had to replace all my float fittings. I used the Univair drawings to weld on the new fittings which included the addition of drilling out the aft end plugs of the lower longerons, tapping them and adding a 1/8 pipe plug. You periodically pick up the tail as high as it will go, remove the pipe plugs, fill the longerons with tube-seal or equivalent and let it sit for a while. Put the tail back down, let it drain and replace the plugs. I guess this stuff creeps uphill quite a bit and if you have cracks or pinholes in your welds it will seep out for days (perhaps not if you have a powder coated or heavily painted structure). That stuff can make a helluva mess and good luck trying to get paint or anything else to stick to it if you don't get it all off. The Stinson, when sitting on floats has the lowest point of the fuselage not at the tailpost but at the aft fuselage float fitting. That is where my fuselage rotted away. The person who did the original float fitting had not made the aft plug mod and I'm not even sure that it was even on the drawings at that time.
I am speculating that this mod was made because when welding on the fuselage structure any protective coating inside the tubing will be burned off by the heat transfer of the welding process (I'm sure that's what happened to mine).
I know this is not a Stinson forum, but I just thought I would share this with fellow T-Crafters.

Bob