Aileron Rigging/Deflection Adjustment

[whee]

I've been working on my rigging off and on for a few weeks and can't seem to find the solution to a problem we have encountered. Our right aileron has uneven deflection regardless of were we set the neutral (control stick centered) postion. We are getting 17* down and 24* up. So we are still getting the proper 40* total deflection but we can't figure out why it is uneven. The left aileron deflections are correct with no issues.

I thought maybe the bell crank was not centered at the neutral stick position but it is.

Any idea what the cause could be? I'm sure it is something simple but I can't see the forest for the trees.

[Aero_tango]

Hey Whee,
Refer to post #5 below. In my case, both ailerons were at +24 / -20 degre
Short story, differential aileron deflection was designed-in, but still spec’d at +/- 20 on the plan...

[whee]

Thanks Aero-tango!

Now I need to figure out why my left aileron doesn’t have differential deflection. I’m sure it’s something not right at the bellcranks.

[jaredyates]

A good cross check would be to measure the length of the two pushrods. If they are different, then that would point to the bellcranks not being zeroed the same.

[whee]

Your probably on to something there Jared. My rod lengths are different. I had to lengthen the right rod because the rod end bearing was impacting the hinge before getting 20* up deflection. The right side bellcrank is exactly square at neutral but the left one is a smidge off.

[Battson]

Yes, the push-rods connected to the bell cranks have screw-in aurora bearings to adjust this very thing. You can screw them out a few turns at each end and get a lot of adjustment.

If the bell cranks are not both square at the same time, then you have made the primary control cables different lengths from port to starboard. You can adjust that with the turnbuckle at the bellcrank on the primary cable. The turnbuckle at the cross-over / carry-through cable is the one to adjust to control tension in the whole system.

The best process is to adjust the primary turnbuckles so the bellcranks are all square and the tension is right (20 to 30lbs in primary cables, 30 to 40 in the carry through cable), then adjust the pushrod length to get the ailerons in the right place.

That is my understanding, not guaranteeing it is exactly right.

[whee]

Thanks Battson. My understanding is the same as yours.

Something must be amiss in my system. I have reset the rigging so the bellcranks are square. In order to achieve 20* down on the left aileron the right aileron must deflect 24* up. When the pushrod on the right aileron is adjusted so the trailing edge of the aileron is slightly up (1/4”) the rod end bearing just contacts the hinge assembly at full deflection. Also, there isn’t enough adjustment in the rod end on the left aileron to get the trailing edge to be slightly up. I can get it about even with the trailing edge before the end bearings bottom out.

Guess I have some figuring to do. Thanks for the help guys.

[svyolo]

Whee,
Both bell cranks being square will obviously effect this as you have already mentioned, as well as others. The other big variable is distance in the two pieces of plate that form the hinge on the aileron side. The horizontal distance of those holes from the hinge line will affect the differential angle of aileron actuation.

There are two easy ways to mechanically effect differential ailerons. One is with an offset bell crank. The other is with an offset control horn, either at the stick, or the control surface. It looks like Bob did it at the control surface.