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Can lift struts be straightened?

supercub

MEMBER
Let me check my GPS, gee how'd we ever navigate w
I have a a front and rear sealed lift strut for a J-3 Cub that have slight bows in them, absolutely NO crease at all. Can these be straightened? If so, is there someone that specializes in doing this, or how does one go about doing it. I haven' measured them yet, but I'm think there's only about an inch or so off set from one end to the other. Thanks
 
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They will straighten pretty easy, this is not a huge force type of job. If it was mine, I would lay them on flat table/floor with the bow up. Find highest part of bow and put tape to make it. Most bows are not in center of the strut, so measure out from the tape to the closest end. Now put a 1-2 inch padded block under one end and another at the same distance from the tape under the strut. Very push down at the center of the bow it should bend back pretty easy. Take your time and check your progress several times, you will have to go past straight due to spring back that is the reason for the blocks. Pretty easy to make a single bow into a S bend if you get in a hurry. Two experienced guys and a saw horse can do it in a few min. The trick is to find the apex of the bow and support equal distance form that as you straighten. Others may have different advice mine is worth what ya paid for it.
DENNY
 
If the bow is slight, and centered, the jury struts are enough. If it is not centered, that may mean metal has been stretched. That is more of a problem, structurally.
 
depending on WHERE the bend is on struts, you may need to check forks for damage, and or STRAITEN the strut attach fitting on fuselage(they get bent) big crescent wrench.... it will bow struts if misaligned
 
Are these struts bowed fore and aft or up and down?

If fore and aft the bend may have been caused by improperly pushing the airplane. Pushing the plane by grabbing the middle of the struts is a no-no. I know, it is done all the time. Sometimes it can be done safely, other times watch out.

If up and down someone may have lifted the plane with the struts or perhaps the fuselage attach fitting has somehow become bent in which case the forks are being subject to improper forces.
 
I have seen bowed struts with no kinks and just a slight bow. The struts are mild steel. Support eack end and push in the middle and see what happens, you got nothing to loose. I tried it, didn't kink but looked like a wet noodle with the bow going both up and down. It now lays in the scrap heep beside my hanger.
 
Years ago while glider towing in a PA-18A-150, glider released and I did my “normal” left turn continuing into a split S. On the recovery, I hit one hell of a bump, and the jury strut clamp slid up the rear strut a ways, leaving a big bow in that strut. Needless to say the rest of the flight was very docile with gentle turns and low airspeed. On the ground, careful inspection of the strut fork, move the clamp back into position which straightened the strut. Investigate why the clamp moved and made appropriate corrections. The airplane is still happily towing gliders today with the same struts installed some 30 or 40 years later.


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I also have a mild bow in my rear lift struts. Plane flies straight as an arrow. Any problem with leaving this or need to try and straighten?
 
I also have a mild bow in my rear lift struts. Plane flies straight as an arrow. Any problem with leaving this or need to try and straighten?

Is it a bow in strut or A BOW CAUSED BY BENT LOWER ATTACH FITTING??? Big crescent wrench will correct the fitting angle.

Where is the bow? Above or below jury struts??

Are jury struts and clamps incorrect position??

Jury struts are 2 different lengths per side....


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I’ll have my IA look at it on inspection. He maintained several cubs for the state of Utah and will know the cause. Sounds like the answer is not to just leave them.
 
Windy, we’ve met a long time ago. You know my dad’s friend Claude.
 
Rigging of the struts has you adjust the jury struts so the wing struts are straight. Had a customer ask me why his jury struts weren't aligned once and showed him it was to make the wing lift struts straight.
 
The short answer is that yes, you can straighten struts. It's done all the time by laying them on a set of sawhorses and gently pushing down against the bow to get them straight.

Like others have said though if the bow was induced by something in your rigging, that should be addressed.
 
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