Landing gear struts

[MattS]

Hello from Brazil. I've been traveling a lot lately so have only been able to fly about 10 hours on PR-ZJO. I'm back in town for a few weeks so tweaking some things that I've found (fixed a couple oil leaks, installed new tailwheel from Eric, adjusting seatbelts, etc). One thing that has me stumped is that the airplane always sits with the right wing much lower than the left (8 to 10 inches at the wing tip). After visiting with Mark about leveling the airplane, everything seems to be correct including wing dihedral, etc. The issue is that as soon as I "un-level" it, she drops back with the right wing down significantly. The adjustment on the shock strut rod end have the same threads showing. Today I measured how much the cylinders are out of the strut. When the airplane is sitting on level ground, the right cylinder is extended 1.875" while the left is only extended 1.25". This results in the right main having a much wider stance and therefore putting the airplane on an angle. Before I start adjusting the threaded rod end bearings, I wanted to check if anyone has seen this before and what else could be causing the cylinders to be that different.

Thanks!
Matt

[Bdflies]

Hi Matt,
Do you know if the situation you describe has always existed, or is this a recent development?

Bill

[Mark Goldberg]

Matt, you might consider taking apart your shock struts and checking out the heavy die springs. Free, they should each be 8" long. Maybe one has been damaged. Be careful you don't damage the o rings though because sending things to Brazil is not easy as you know. Mark

[MattS]

Bill, It was like that when I bought it, but not sure if they built it like that. Nothing else shows any kind of damage--just the strut is "tired". I guess that is my question for you builders, is it possible to get it that far off during the build process? Mark, thanks I will look at that--- yes, shipping is an issue! Thanks!

[Bdflies]

I may be the wrong one, to respond, since I didn't build my struts, but I've marveled at their construction and am familiar with how they'd be built. Besides, I'm so full of opinions, I can't help but opine...

when you unweight the right gear leg, does the strut retract the .6" over-extension? I'm guessing not. With the right gear un-weighted, can you push the rod into the strut cylinder the additional.6"? The way I'm thinking, if the spring has yielded (relaxed or bent) or broken, then there's going to be free space between the spring and the piston. If that's the case, you should see some movement of the rod in the cylinder. At rest, there's something like 3,000# force, pushing the piston down the cylinder. So, if you can move it in, by hand (indicating a relaxed spring), then there is something badly wrong with the spring.

If the rod is real tight and and you can't move it in/out manually, then I'd guess it's alright. It's a hell of a spring! If your struts are factory, I'd guess tolerances should be pretty good, so a rod difference of .6" should be unusual. Not knowing how the factory makes them, I'd say unusual, but not impossible. If they're made by someone like me, who knows... +- .6" might be pretty good. A marvelous thing about this gear design, is that there's adjustment available, to remedy this very situation. Screw the left rod end out, a bit and screw the right one in (BEING VERY CAREFUL NOT TO PRODUCE INADEQUATE THREAD ENGAGEMENT). Did I mention to be very careful not to compromise thread engagement?

As a point of comparison, the factory built plane, that I sold recently, had about 8" difference, left tip to right tip. The very nice, very expensive, factory built plane, currently in my hangar, has a 5" difference, left tip to right. I measured it today. And I assure you, there is NO way to adjust this. I'd worry about it if the fuel cross-fed and drained out, or if I kept hitting my head on the low wing. Neither happens...

I hope my ramblings are of some help.

Bill