Brainstorming request; repairing a well-rusted cluster.

[DanBrown]

Re: Brainstorming request; repairing a well-rusted cluster.

Well, I think Bill Berle has it right!! The 60 year old fleet is all I can afford to own and fly -- even with replacing the struts the T-craft comes to far less than one of the new LSA ships. Mike, I wish I were in your shoes and have the time, place, skill and energy to undertake a restoration project. More power to you and keep giving the gurus something to noodle on.

[N96337]

Re: Brainstorming request; repairing a well-rusted cluster.

if this plane is for display purposes only use some bondo
I doubt I could ever trust this one out of ground effect
Sorry to be harsh but aviation is more about safety than sparing cost in my opinion.

Why could you never trust this out of ground effect? Do you not realise that ALL of your fuselage and gear were once a pile of tubing? The whole airframe should not be condemned just because some lower cluster has gotten water and rusted.... the affected parts are cut out, new are spliced in and you have a part that is every bit as strong as original..in fact, according to the structural engineers I've talked to in the last 25+ years, it will be a bit stronger. If it was mine, I'd be very tempted to put new lower longerons in as well, so I'd have a couple hundred dollars in tubing and welding material... is this more expensive than buying a different plane? What gaurantees that the other one I buy wont have some corrosion?? I agree that aviation is more about safety than cost, but if you can do a repair safely without buying a whole other plane, what's wrong with that????? I've repaired much worse than this, and they've not failed yet...nor do I ever expect them to...and some are used alot harder than any Tcraft ever will be!
JH

[tawadc95]

Re: Brainstorming request; repairing a well-rusted cluster.

You guys are making an assumption that I am not willing to gamble on......................what makes you think the rust is limited to that part only of the frame and what makes you think the rust is limited to the outside of the frame in other places.
Everything has its time to go,just because an item is old and historical does not necessarily mean it is or should be salvageable. It is the way of life,probably half of us on here are old and unsalvageable by now.
As for my comment on the bondo I did not see anyone elses comment on using bondo and meant it exactly as I said it.
As for cost,yes it has to be considered that is also a way of life but my philosphy with mechanical items is if you can't afford to do it impeccabily you can't afford it or it is not your real priority. I purchased an airplane I could afford to maintain to high standards,not wastefully but to the best degree of safety and RELIABILITY I can attain.
Also I personally would feel real bad if I encouraged someone to go through with a project they ended up hurt or worse in so I am rather cautious about what I lend my encouragement to on here when we don't see the whole of the project.
In short be safe Mike I would rather see a frame retired than see you retired.
And don't take this as meaning to throw it out......just don't make assumptions about what you can't see either.
RESPECTFULLY SUBMITTED,Chris

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

Chris makes an good point concerning the inner condition of tubing we can't see, and it's related to the thread on struts.

Last winter, while removing paint from the fuselage, it was easy to ident areas where I'd find rust beneath the paint - the paint was buckled. Also, if I saw some discoloration in the paint, I'd give it a lick with the wire brush and would find rust. But there were at least two occasions where just for grins, I'd move several inches away and clean off the paint, only to find a rust hole. So it looks like my sandblaster and wire brush will get a workout as all the paint will have to come off.

The Tcraft community's attention is currently on the lower end of our struts. I'm thinking the same problem (no external signs, but worrisome amounts of internal corrosion, not readily apparent) exists with our fuselages.

So, how does one go about evaluating the condition of the fuselage tubing without hi-tech NDT? How did restorers evaluate their tubing five years ago? - MikeH

[N96337]

Re: Brainstorming request; repairing a well-rusted cluster.

Chris makes an good point concerning the inner condition of tubing we can't see, So, how does one go about evaluating the condition of the fuselage tubing without hi-tech NDT? How did restorers evaluate their tubing five years ago? - MikeH

Mike, I've used an automatic center punch to test tubing and always, if there's any doubt in my mind, I'll cut a tube and take a look! I'll also replace a tube or tubes if there's any sign of corrosion. That ties into me saying (agreeing with Dave) to replace the whole longeron on your repair there. That cluster looks intimidating maybe, but it's like a long cross country flight... just a bunch of little hops all added into one.
I'm planning on replacing BOTH my lower longerons this year, from just aft of the main cluster behind the seat back (rear float fitting attach point) as there's already a splice there, and it will give me a good chance to take a look forward to the landing gear and strut attach points from the inside out (I'll use a flexible bore scope) and also to get some positive coating of Polyfiber's Tubeseal in those areas. My plane came on floats from the factory, and has served alot of it's life in the back country, so I think it's time to give it a good look, plus it'll give me an opportunity to get things all square and fresh in the tail.
One of the advantages of a tube and fabric plane is that it can be rebuilt entirely, and brought back to new tolerances fairly easily... unlike a stressed skin aircraft (not that they can't..it's just not as economically feasible).
I've found rust in odd places in tubing, and also cut tubing that I was sure would have internal rust, only to find it nice and shiny inside! My Bellanca longerons had very very small rust spots, maybe 1/16" in diameter and a few inches apart in the bottom of the tube. I replaced both longerons there, from the rear spar back, so it should be good for another 60+ years, especially after they're treated with Tubeseal!
I wish you were closer Mike, I'd be glad to help with your repairs.
JH

[Guest]

Re: Brainstorming request; repairing a well-rusted cluster.

All this strut AD debate has got me wondering why I never bought one those little ultra sonic wall thickness measuring tools to check tubes like longerons etc, struts, tanks...

Maybe next year.

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

splice in a new section of longeron and then do an outside sleeve splice on each cluster tube

Dave - if I do a splice by inner sleeve for the longeron ( I assume that's what you were thinking) and then an outside sleeve splice for each of the tubes joining the cluster, you realize that will make each of these secondary tubes have a larger diameter than the original. Right?

Second; were you thinking of splitting the outer sleeve in half along it's length? I don't see how the outer tube would slip over the original tubing unless there were some 'spring' in the original tubing. - Mike

[Guest]

Re: Brainstorming request; repairing a well-rusted cluster.

Hi Mike,

I was imagining that the custer tubes had enough flex to allow an oversize tube rest on the side of the longeron and slide over the cluster tube. I have done this but yours may be too short or stiff to do the same. The more cluster tube you remove the lesser the flex you need in the remaining cluster tube. There is min length requirement in 43-13 so don't go wild, look up the min.

Do this thought experiment, this will work too;

Jig up the frame so that you can cut out bad pieces of tubing and not lose dimensions (ie position of remaining pieces)

Remove the offending longeron and make a replacement that fits good. Do not weld in place.

Cut out the offending portion of the cluster tube(s)

Prepare an outside sleeve splice tube for the cluster tube(s), make it a couple of inches longer than the minmum. Create initial shape at the end(s) of the cluster splice to fit against the longeron (and other cluster splice if they exist).

Check cluster splice longeron end shape by sliding cluster tube splice in place, put longeron splice in place and clamp longeron into position. Check fit against longeron and trim as required, this is why I say make 2" longer than minimum.

When cluster splice ends are satisfactory slide each one onto its respective tube and weld longeron in place. Then slide each cluster splice into place and weld.

Of course if there is more than one cluster splice make sure they fit together as a group also not merely against the longeron.


Hope this helps,

Dave

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

Before you cut anything apart, make up a jig for it.

Bill - as you can tell from the re-incarnation of this thread I'm thinking seriously about putting more time in before other things distract me (see attached).
I took a good look at the cluster and the tubing of major concern - all lie within the same plane, so a jig is possible with minor work; however, within about a 3 ft radius, everything seems to be held in place so I'm wondering if (except for the longereon) I would even need a jig; I would only be removing about 3" from the ends of the joining tubes. - Mike

[Howard Wilson]

Re: Brainstorming request; repairing a well-rusted cluster.

Get that plane done before they arrive Grandpa!!!

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

Get that plane done before they arrive Grandpa!!!

I'm scaping as fast as I can!

[crispy critter]

Re: Brainstorming request; repairing a well-rusted cluster.

Congrates papaw.......get'er done!

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

Congrates papaw.......get'er done!

not my work! I'm just going to be a granddad! but I was planning on only one at a time! - Mike

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

Oops, too late - Mike

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

First off, thanks to all who helped me brainstorm my cluster problem (see attached). Two events overlapped and I think I have my approach.

I had my AI come by and look at the conditions of my wings, and oh, by the way, could you look at this fuselage and let’s talk about that cluster.

With the wings – I had been doing some repairs, and to this layman I was good to go, but I wanted a pro to point out additional things that might have to be repaired. He didn’t. He looked them over and gave me clearance to cover! Not that I’m ready (some of the wires have rust and I want to remove the wing tank for cleaning and testing), but it’s good to know there are no splits and there is some reasonable certainty they will stay attached to the fuselage.

With the cluster – I’ve been eying it for about a year, mulling over all the suggestions given. About a month ago I looked at the pitted longeron and maybe if I squinted a bit, the pitting wasn’t THAT bad. If I could cut back the three damaged members, I could indeed use an external splice on each. Enter the AI with a punch and hammer. Tap, tap, tap and he gives me the green light! Apparently it looks worse than it is. Additionally, he points out (you can’t see it in the photo) this is where the longeron steps down in size, so there is a second wall of tubing inside that pitted member. He continued his inspection and except for the places I knew needed work, gave his OK. So, unless we get a big surprise when I begin sawing on the damaged members, we’re going to be OK. Of course a lot depend on being able to spring the damaged members enough to slip on an external sleeve.

So, a good afternoon. - Mike