Struts

[Dan Michaels]

Re: Struts

9/1946 BC12D

I started all the wanting to build new struts as owner manufactured until I talked to the FAA. Even if I built the new struts to new specs they still want the AD enforced unless I have an AMC. Very stupid and I am not even sure they are right.

As it stands now I think if I have my struts checked (This week or next) and they come back good. I then think I can heat and run the oil through them, then seal them. Do the paperwork for AMC and get by without ever having to mess with it again. I have to talk to a DAR first for some input on why this will work as well as the factory new set. I think that with enough info and data it will go through.

Dan

[Forrest Barber]

Re: Struts

Keep us informed. AMC ? AMOC ? Tell me about this "sealing" old struts. That is the thought of many.

[Dan Michaels]

Re: Struts

Keep us informed. AMC ? AMOC ? Tell me about this "sealing" old struts. That is the thought of many.

Yes Alternative Method of Complience.

I was thinking a rivet would do the trick, Fill with hot oil, drain and plug the holes with two rivets.

Dan

[Forrest Barber]

Re: Struts

That is how we do the fuselages. it is called a paralkalon (sp) drive screw. i imagine the FAA of today would want a permanent seal.
If a fuselage integrity is not compromised then the last weld uses up the oxygen inside thus no rust. If there are no weep holes. I believe that has been the problem . How do you intend to seal the struts? They have open tops plus the "drain hole" at the bottom. The numerous sizes of approved strut sections can be a problem too.

[Dan Michaels]

Re: Struts

Keep us informed. AMC ? AMOC ? Tell me about this "sealing" old struts. That is the thought of many.

Forrest,

Talked to H.G. Frautschy today (He says Hi). He said you already have a DER that you have been talking to. He also said that what I am trying to do should work. If it is easier for you to talk to the DER why don't you ask him about it, price and if it will work. If you would rather I did it if you could get me some contact info.

Basically if you take the struts off and have the whole strut ultrasound. Fill the strut with boiling linseed oil then drain. Seal the strut by any method he suggests. Set a time factor of say 20 or 30 years or unlimited. What this does is gives an alternative method of complience. If you posted the projected cost of the DER to the group or was able to send a letter to all Taylorcraft owners and get a "Willingnes to split the bill" type of thing it may not cost that much in the end. There really is not much engineering to do and we may be able to just submit it without a DER. I do not think one is required although I thought it would have a better chance of passing.

Dan

[Forrest Barber]

Re: Struts

e-mail me direct, there is a lot to do to "seal" the struts. imagine the welding at the tops, new bushings etc.... I am sorry but a lot of the welding done by some shops including the present factory does not hold up to any standards that I am aware of in Aviation. [email protected]
My project at the moment will be spars.

[Hank Jarrett]

Re: Struts

A strut is a complex weldment with some fairly critical loads going through it. Not something you want to make a mistake on. I wanted to do the same thing (make an old strut meet the new, sealed strut standard through inspection, cleaning, treatment and welded modifications).
It CAN be done, and I would still like to do it, BUT, to make it cost effective we need to set up a line and do a bunch of them all at once and establish proper procedures, inspections and tests. It WON'T be cheap and it might be less expensive (I HATE the word "cheaper") to build new ones from scratch.
My old struts are in perfect condition, but are stored in the workshop in my hangar. Darned if I will throw them away. They will be perfect for a homebuilt project (that will not carry the re-inspection requirement - except the one I will do each year because that is what we SHOULD do every year).
I am hoping the FAA will modify the inspection requirement to something reasonable so I can put my nice original struts back on my plane.
Hank

[Dan Michaels]

Re: Struts

A strut is a complex weldment with some fairly critical loads going through it. Not something you want to make a mistake on. I wanted to do the same thing (make an old strut meet the new, sealed strut standard through inspection, cleaning, treatment and welded modifications).
It CAN be done, and I would still like to do it, BUT, to make it cost effective we need to set up a line and do a bunch of them all at once and establish proper procedures, inspections and tests. It WON'T be cheap and it might be less expensive (I HATE the word "cheaper") to build new ones from scratch.
My old struts are in perfect condition, but are stored in the workshop in my hangar. Darned if I will throw them away. They will be perfect for a homebuilt project (that will not carry the re-inspection requirement - except the one I will do each year because that is what we SHOULD do every year).
I am hoping the FAA will modify the inspection requirement to something reasonable so I can put my nice original struts back on my plane.
Hank

First homebuilders manufacture struts all the time and for planes with a lot more critical load than the Taylorcraft sees. It is not more important to weld a strut right than it is to weld a fuselage repair. I am not saying to just go out in the garage and weld one up. It has to be done right. A&P's weld on the fuselage all the time. At this point I think just getting an AM of C will be much easier.

That being said I have mine off now and have looked at them. I also have the section from the AC 43.13-1B that shows how to fix the problem. Since this is from a FAA control it should be no problem to get it through.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2006.pdf

6-42 Tube interiors

All that I can see that is needed is to have the inside of the tube inspected, then seal the tube from air or moisture as described in the section 6-42. It would be hard for the FAA to say that, that is not enough if they themselves say that it is an acceptable method.

I also see from removing my struts that one could use a Fiber optic scope to look inside the tube. This is about the same as the other AD on the Fitting attachment. It could be done each 4 year annual at not much of a cost. Just lower the top of the struts and send the scope down.

Dan

[Hank Jarrett]

Re: Struts

It's not the "making" of the strut that is the problem, it's the FAA acceptance of your method. That isn't as hard for a homebuilt as a certified aircraft. They don't need a rational reason to say no to your process. ALL weld repairs to critical load path structures are critical. Please understand, I WANT you to be successful. I want my original struts back home on my 41, NOT on a homebuilt. I have plenty of beat up struts to cut up for a homebuilt.
You don't just have to seal the tube from air or moisture as described in section 6-42, you have to do it so the FAA will accept your process, and they DON'T have to be reasonable. I really hope they are, because as long as the strut is sealed, you have met the intent, but the FAA is famous for being unreasonable if there is ANY risk the guy making the decision can be held accountable if something goes wrong. There are LOTS of great people in the FAA, but they are VERY conservative (which is usually very good, but sometimes a pain).
I have worked with the FAA on GA projects and would love to help any way I can, but i don't want you to be "bummed out" when you do everything "right" and they turn your method down anyway. It DOES happen more often than not.
Hank

[Dan Michaels]

Re: Struts

It's not the "making" of the strut that is the problem, it's the FAA acceptance of your method. That isn't as hard for a homebuilt as a certified aircraft. They don't need a rational reason to say no to your process. Hank

No it is not. It is no more than a log book entry. "Owner manufactured part" I already called the FAA. Nothing more than a log book entry.

As far as sealing the tube goes it is their method they cannot disput it they print it. This is the reason the new struts do not have to comply with the AD.

So just for argument lets say you take a strut off and have it inspected. It comes back with a clean bill of health. The strut is now airworthy. The AC says that if you seal the tube from air and moisture it will not be subject to corrosion. Everything right from the FAA documents. How are they going to say that it will not stand up? I would go back to them and say "So I cannot believe everything in the AC then".

I think you have a different opinion of the FAA than I do. I think that if you just whine at them they are not going to listen. If on the other hand you get all the facts to back up your claim you have a better chance. If you get all the information from their AC you have an even better chance. What are they going to say, "well we really did not know what we were talking about when we wrote that.

The AD spells it out, you have five ways I think it said to comply. One of those ways was AMOC. If they did not want you to do it any other way they would not have put that in there. They would have said there is one way and one way only.

I am really talking about two differnet things here. The alternative method of checking for corrosion would be a bore scope through the adjusting hole.

The sealing of the tubes would be a request to eliminate the AD. This could be done no matter what way you checked for corrosion.

Dan

[Hank Jarrett]

Re: Struts

Dan,
I'm not trying to discourage you. In fact I WANT you to get this to work.
All I'm trying to do is warn you there are some pot holes in the road you should be ready for. I have been down this road and there are people in the FAA who will try and stop you.
There is a little more to it than a simple log entry. Whoever told you that was all that is needed at the FAA is probably going to be over-ridden. That is just the paperwork part for the logs. You still need to prove you have eliminated the hazard and sealed the strut by the approved (or an equivalent) method. I haven’t seen an approved method to seal an old strut and I also haven’t seen the detail drawing of the new struts to see how they seal both ends in manufacture (do you have either of those?). They can be different, but you must prove your method is equivalent to the manufacturers. That is going to require some engineering analysis be submitted to the FAA and accepted (one of the three requirements for acceptance of an owner approved part, an accepted design, a quality plan or your manufacture of the part to the original specs). Even if you use the same method as the factory, you have to prove you did it to the same design they used and the same quality standards. I have done MANY owner produced parts and they ALL had to be approved. Usually it is at the FAA local level and is no problem. Do you have someone who is willing, and qualified, to accept your modification?
As for the sealing being their process (that they cannot dispute), yes they can. They can dispute anything they want to. YOU have to prove you did it to the TC holder’s requirement (that was previously accepted by the FAA). The FAA didn’t write the sealing process, the factory did. Have they shared their drawings with you? If they did, PLEASE post them! I am an Aero engineer (as I suspect you may be also) and I would be happy to help make this work. I am NOT trying to throw stones or stop you. ALL of my comments are provided to help you succeed!
I may have missed it in all the junk from the FAA but I never saw in the AC that sealing an old tube was an acceptable practice to comply with elimination of this inspection by individuals. NEW MANUFACTURED struts, yes, but I didn’t see that it applied to old ones. It may say it isn’t subject to moisture or corrosion if sealed, but that doesn’t mean they will accept it as an alternate compliance. Just be ready. One of the ultra conservative types can still say no, and they don’t seem to need a reason (look how long it took to get them to take out Eddy Current as an inspection method for corrosion, and that was an obvious mistake). As to believing everything in the AC, no, you can’t. They have proven it repeatedly. It’s not fair, but that is the way it is. They can change their mind or say it doesn’t apply in this case anytime they want to.
You need to understand I’m not just one of the whiners who wrings his hands in the face of adversity from the FAA. I’m a problem solver and have cooperated with the Small Aircraft Directorate in Kansas City on MANY projects. They are GREAT guys and 90% of them want to help us get our planes back up safely and for the least money. The 10% on the other side are as much problem for the good guys at the FAA as they are to us. You ARE right that they don’t have a lot of patience for those who just whine about the problem. Neither do I (I’m a bit on the crotchety side myself). You are absolutely right that if you get your facts from the AC and have your ducks in a row you have a reasonable chance of success (not guaranteed, but reasonable).
I like your idea of using a Borescope for inspection, but having seen the inside of a strut, be prepared. There is a TON of slag, old oil and contamination in there and it will be really hard to inspect it visually, especially at the bottom end, where the corrosion would be the worst. I actually designed a bead blast extension that could be used to blast the ID of long tubes years ago that worked pretty well. They wore out really fast at the 90º bend at the end but gave us some beautiful surfaces to inspect. I would feel much safer with a strut that was Borescoped than one that was X-rayed.
Finally, please remember, I AM on your side. I have fought these battles before and I don’t want you to give up and get discouraged. I just have to focus my efforts on getting the rest of my plane back together now. I hope when the wings go back on you will have had complete success and I can put my original struts back on.
Let me know if I can help.
Hank

[Dan Michaels]

Re: Struts

Hank,

First you misunderstood some of what I said.

FAA said that owner produced part does not have to have an approval just a log book entry.

This does not get rid of the AD according to the person I talked to at the FAA. "I think he is wrong" on that part.

I never contended that you could eliminate the AD without approval.

I also know that you need approval to do an AMOC which still does nothing to the continued AD. Unless I think that you show them with their own data that it will stop any corrosion from happening in the future. Two things on my side there. One; it is in their publication. Two; they gave approval to the new struts based on sealing.

I am continuing to respond to this to let all know that I am serious about resolving this and I do need help as I have never filed for an AMOC. I have mine handled, but I would like to help others with this problem. I do not think that it is that big of a deal. If we could get a DER onboard it would be even easier.

If anyone has an old set of struts that are not any good it would be a big help if I had the two ends that attach to the wing. one of the bottom parts would also help. No more than one foot of each.

By the way each time someone tells me I cannot do something FAA or other it just motivates me more. Let them tell me no, it will just motivate me all the more.

Dan

[Hank Jarrett]

Re: Struts

Dan,
I really think we may be saying the same thing different ways and are probably in violent agreement.
The real question here is how do we do it and how do we get what we did accepted. Let’s drop the semantics discussion and look at what needs to be done.
As I see it we need the following;
First thing needed are drawings of the original and sealed strut construction. Do you have any drawings of either one (or does anyone?).
Second we need to see if we can design a mod to an open strut to seal it at least as well as a new sealed strut without compromising the integrity of the strut. I should be able to help if you need it.
Third, if we can modify a strut we need a procedure to inspect the strut beforehand to insure it is corrosion free to a level acceptable to the FAA.
Fourth, we need a way to insure there is no future corrosion through exclusion of moisture or oxygen from the interior.
Lastly we need to make sure all of this is acceptable to the Feds so we haven’t wasted our time.
Along the way it would be nice if we can do the whole process for less money than we can buy a new strut.
I’m ready and would like to see the tribe take this on. Who has drawings?

Hank

[Dan Michaels]

Re: Struts

We only need a drawing if we are going to manufacture an owner manufactured strut. The Original strut is an approved strut as long as it is airworthy. Sealing the strut should get rid of the AD as it does on the new strut. Sealing it with epoxy is a minor change and would need nothing more than a log book entry.

I have a call into a company in MN that does non-destructive testing. If I have the strut inspected and it comes back within the specs outlined in the AD it is airworthy, now all that need to be done is keep it in that condition. they may be able to give me a report on how close to original the old strut is. also I think a picture of the strut will help. It has been done by H.G. over at EAA I think. Along with this report a list of all the tests that have been done so far on this list would help.

I plan on sealing the strut with epoxy unless you have another product that is already approved. This is why I need the old struts. If I were to use the epoxy on them and send them along as an example it would go along way I think in explaining the process.

I have a call into Andrew at the FAA who is responsible for approving Taylorcraft AMOC for this AD.

One other thing I am looking into is a way to do a borescope inspection on the spar that does not have the adjusting screw. Just getting the borescope approved would be a big help as most IA's have a borescope or should have.

Dan

[Robert Lees]

Re: Struts

The struts are ten feet long. You'd need a five foot borescope to see it all from both ends. Since you can only gain access from one end (and that's the rear adjustable strut), you need a ten foot borescope.

How to get any borescope inside a front strut to the original design beats me.

Good luck, but I think you're flogging a dead horse.

AD's are a pain, but it's part of flying. Pay the $2000 and have done with it.