streamline strut repair

[Guest]

Hi all,

Has anyone seen, made, heard of a streamline wing strut splice using the inside sleeve method?

AC43.13-1B allows only outside sleeve repairs for lift struts.

But I am thinking that someone must have done and gotten approval for an inside sleeve splice especially perhaps a factory since its a nice way to use portions of tube that may be too short.

Any clues if such a thing has been done?


Dave

p.s. I am referring to AC43.13;1B paragraph 4-95 when I refer to inside sleeve splices.

found here=> http://rgl.faa.gov/Regulatory_and_Guida ... r%2004.pdf

[barnstmr]

Re: streamline strut repair

AC43.13-1B allows only outside sleeve repairs for lift struts.

Dave,
I have seen this done on wing lift struts.

(1) First, the AC43.13-1B is advisory material. It is not regulatory. The FAA has stated that the content of 43.13-1B may be accepted as approved data. It never states that this is the ONLY means of compliance for repairs.

(2) I have read through this and I do not see anywhere where AC 43.13-1B says wing lift struts may only have outside sleeves. It does recommend the outside sleeve figures, but I cannot find where it prohibits inside sleeve repairs.

[barnstmr]

Re: streamline strut repair

Dave,
The key is to use the tables supplied with the figures to ensure that the original strength is retained by proper fitment of the inside and outside tubes. Also strictly adhere to the weld patterns shown without deviation.

[N96337]

Re: streamline strut repair

I've never seen one, but I'm with Terry on this.... I'd get the info together and send it in and see what they say! Outside patches look terrible!! I had a J3 come in one time with a "swelled" strut...about made me panic when I saw it....I thought it had been frozen. When I got to digging in further, it turns out that they'd done an outside patch and then faired it in with body filler! Needless to say, it got stripped off and just painted.
I'd love to see what you come up with!
John

[crispy critter]

Re: streamline strut repair

Personally, The problem I would have with an inside splice/sleve on a strut is the lack of weld surface. You only have a single weld where the two outside pieces join together over the sleve. Then you have to drill and spot weld. The outside splice weld might not look as pretty but I feel like it would be much stronger and more weld/bonding surface. An outside splice done correctly and neatly doesn't look too bad. Of course the best way to repair a bent or broken strut is with a new one,lol.

[Guest]

Re: streamline strut repair

Personally, The problem I would have with an inside splice/sleve on a strut is the lack of weld surface. You only have a single weld where the two outside pieces join together over the sleve. Then you have to drill and spot weld. The outside splice weld might not look as pretty but I feel like it would be much stronger and more weld/bonding surface. An outside splice done correctly and neatly doesn't look too bad. Of course the best way to repair a bent or broken strut is with a new one,lol.

Hi Kevin,

Some things can't be purchased new.

But I would like to know more about what you are thinking about the "red" statements above.

My thinking is that a round tube inside splice has the same issue and yet we accept that. The rosette welds are optional and not required when you have a good fit of the inside sleeve.

4-84. ROSETTE WELDS are generally
employed to fuse an inner reinforcing tube
(liner) with the outer member. Where a rosette
weld is used, drill a hole, (in the outside tube
only) of sufficient size to insure fusion of the
inner tube. A hole diameter of approximately
one-fourth the tube diameter of the outer tube
serves adequately for this purpose. In cases of
tight-fitting sleeves or inner liners, the rosettes
may be omitted.

Dave

[Hank Jarrett]

Re: streamline strut repair

I have seen several struts with an inside doubler (and own a few in the "pile"). A couple were REALLY well done and the only way you could see the repair was to look for the rosettes (which were not all that visible with the paint). Some were "OK" and looked a lot better than the external repaired ones I have in the pile. A few are down right scary.
Years ago I was sand blasting a VERY NICE looking strut (not from a Taylorcraft) when the Bondo in a butt joint area blew out. I didn't even know the strut was repaired before! I didn't see any rosettes so we pulled the strut apart (it wasn't hard). There was a carved piece of WOOD inside the strut! The only thing holding it together was the butt weld and that had been ground down flush and filled with Bondo! I wouldn't have done that on a STATIC DISPLAY! What was scary was the strut had been flying on a plane for years with no problems.

Hank

It does go to show that these struts have a LOT of safety margin in tension, and the wood actually HELPED in bending. I still wouldn't have used it for a tent pole.

If you decide to go with an internal doubler, offer to do a tension test on it for max load (struts are generally sized for BENDING in the middle, not tension, so max tension design load will be no where close to breaking it). With that data the FAA should have no problem, if they know what they are doing (which is NOT guaranteed).

[crispy critter]

Re: streamline strut repair

Dave,
There's nothing wrong with the inner splice, and honestly if I was doing it for myself on my airplane I would probably do it that way. The rosette welds are a must when spliceing a wing or landing strut with an inner splice(IMHO). However I wouldn't trust any inner splice if it were done by someone I didn't know.

The outside splice is not very pretty even when do e neatly, but is much stronger and you have more of a welded seem. It can be done either way, but the outside splice is much easier to inspect and as some above has mentioned, it is much harder to hide. Also the outside splice is the recommended method, so if it is ever questioned I don't have to defend or explain myself.

If I'm doing the splice for an airplane I'm working on or own, I will do which ever I'm in the mood for at that time,lol. If its for someone elses airplane or one I plan to resell I will use the recommended method which is the outside splice. But if done correctly either is fine but I still feel the outside splice is stronger.

[Guest]

Re: streamline strut repair

Has anyone seen an L2 structural repair manual and know if perhaps it describes an internal sleeve splice for lift strut repair?

Dave

[barnstmr]

Re: streamline strut repair

Dave, it only shows an outside repair same as 43.13