Jam nut required on strut rod end?

[C5Engineer 1170]

I have been dealing with a heavy left wing for a long time with my plane. It's not bad but during these perfectly smooth winter fly days we have been having lately you start to notice any and all flaws with rigging. About a year ago I messed with the rod end and got it down to just a tiny slight roll to the left. I ran out of adjustment on the rod end though when it hit the jam nut. With one more turn I think it would be almost perfect. Is the jam nut really required? With the bushings and bolt it's not going anywhere. Maybe machine the nut down in half? I ask as it's obviously a critical part on the plane. For those that have never messed with their Rod ends 1 to 1 and 1/2 turns is pretty significant. 

[EDMO 1078]

I think Leni and I both said some time ago that you don't need the nut on the rod end of the strut.  EDMO

[Av8r3400 1179]

I agree the nut isn't necessary for strength in the rod end bearing.  It's there to prevent rotation and self adjustment.

The lift strut obviously won't turn.

The rod end bearing itself could turn slightly without being locked.   It will be able to move nearly a quarter turn with the rotation of the ball end.  If you need another full turn, is there enough meat in the nut to machine it down?  That would be my preference over a lock tight material to hold the bearing. 

Edited 9 Feb 2016 by Av8r3400

[EDMO 1078]

Joey,  Would a shear nut be thinner than the one you have on the rod end?  I still don't think you need the nut or Loctite, except maybe to keep moisture out of your strut.

1/8 turn either way wont affect your flying, but if the threads are tight it probably wont even turn without a nut.

EDMO

Edited 9 Feb 2016 by EDMO

[tcj 150]

I would keep the jam nuts.  They preload the threads holding the strut to the rod end to keep the parts from working or vibrating and weakening them.

[Avid90 12]

If you are now using an AN 315  for a jam nut, try changing itto an AN 316 like Ed suggested.

[MarkD 53]

I agree with keeping some type of jam nut on the strut as tcj indicated, it keeps a preload on the rod end.  Without that preload the rod end fitting could eventually cause wear on the threads both internally on the rod end and on the stud and may even lead to a failure.  If you need only one more thread maybe you could run a die down and get one more thread on the stud. A standard threading die has a front side with tapered starting threads and a back side with very little chamfer.  If you turn the die around and run it down backside first you may be able cut an additional thread very close to the weld.

MarkD

[EDMO 1078]

I agree with keeping some type of jam nut on the strut as tcj indicated, it keeps a preload on the rod end.  Without that preload the rod end fitting could eventually cause wear on the threads both internally on the rod end and on the stud and may even lead to a failure.  If you need only one more thread maybe you could run a die down and get one more thread on the stud. A standard threading die has a front side with tapered starting threads and a back side with very little chamfer.  If you turn the die around and run it down backside first you may be able cut an additional thread very close to the weld.

MarkD

Most AN approved threaded aircraft bolts, nuts, etc. have ROLLED and not CUT threads.  Most general purpose taps and dies CUT the threads, which, along with removing the coating, might weaken or cause the rod end to crack in use.  I would not recommend doing that.

EDMO

[TJay 1041]

Im Not sure if it is needed or not but first I would take it off and go fly it to see if it helps at all, if it does then figure out what you can do, If not put the nut back on and fly it like you always have.

[Guest]

I agree that preload of the jam nut is essential. Can you shorten the rod end just a bit or find a shorter rod end? Since nearly all threads are engaged, shortening a bit should not compromise strength.

[dav8or 20]

Joey, let us know if you find a solution. My Model C speedwing is the same way. I have it adjusted all the way with the jamb nut and still have a slightly heavy left wing. I have seen one Avid that corrected a heavy right wing with shock cord to the controls set to counter the heavy wing as a trim of sorts. I would prefer to have the rigging corrected if possible. I have never flown mine with the right wing tank full and that might be enough for hands off flight but I would rarely if ever carry that much fuel since I do not do 4 hours of flight time with it in a day and I drain unused fuel from the fiberglass tank at the end of the day. I keep the aluminum tank full to prevent condensation. I usually make the longer flights in my Grumman Yankee.

Dan

[EDMO 1078]

I would suggest spending a dime, (or a dollar?), for a shear nut (AN316) to compare with the nut that is on the rod end before you take the strut loose to remove the old nut.   Possibly, the nut already on there is a shear nut?  

For what this nut does, I don't think it would be critical to get an AN nut - something thin bought locally would work.

Medium Thread locker/sealer is always good too.

EDMO

Edited 11 Feb 2016 by EDMO

[1avidflyer 1983]

It's probably been mentioned before, but perhaps a small trim tab on a flaperon would balance things out.  Jim Chuk

[EDMO 1078]

It's probably been mentioned before, but perhaps a small trim tab on a flaperon would balance things out.  Jim Chuk

Isn't there an adjustment on the individual  flaperon controls in an Avid?   EDMO

[C5Engineer 1170]

There is Ed but the will always center themselves. By messing with the individual adjustments you just end up with a crooked stick. I've messed with my rigging in those multiple times and they always end in the same place.