Heavy ailerons when temp goes below freezing, both on ground and in the air

[ao.frog]

Hi gang.

Winter-temps are slowly getting to Norway these days, and I've run into a strange problem: when temps are dropping towards freezing and below, (from approx +5*C) the ailerons are becoming more heavy with lower temps.

Today, it was -5*C so it wasn't far below freezing, but the ailerons where definetely harder to move than the elevator.
They are not "sticky", they are just harder to move.

No problem to move either the ailerons or controlstick, it's just that there's a difference in stickforce when temps are dropping.

It's the same force needed to move the aileron both in the air and on the ground.

I've checked the tightness on the nuts and bolts connecting the ailerons to the wing, and no excess tightness there.

Next step is to disconnect all the linkages from each other and check one by one.

But before I'm starting to remove inspection hatches and cockpit-floors, I'm wondering if any of you have a suggestion as to which part to check first?

It's cold to crawl around on the hangarfloor these days, so it'd be nice to be able to go straight for the faulty part.

So any suggestions anyone?

[BillL]

I have no direct experience, but with temps two things come to mind, lubricants, and thermal expansion differences.

Thermal expansion - I can not think of aluminum around steel that would result ing tightening. If it were, sticktion would be expected.

Lubricants - this would be my first thought, are the rod ends lubed with grease or oil? What are there, 10 rod eyes, and bell crank or 3?

Last thought - autopilot servo - - hmmmm - - that might be the first place to remove a link. I wonder what the factory specs are for free torque vs temperature for the servo? Do you have a servo? Hair dryer to warm it up and check as opposed to removal and re-torquing in the cold?

[Webb]

Check bushing length in aileron bell crank housing. If the steel sleeve is too short for the bushing, it can act like a friction lock. If there isn't adequate clearance, the sleeve can be ground shorter. I had this problem on one of mine.

[sblack]

Aluminum has 3 times the thermal expansion of steel so after disconnecting the servo this would drive my trouble shooting. The aileron attachments and bellcranks bith have a combination of both materials so it should be easy to isolate. Failing that, move to Florida

[Larco]

I like Bill’s idea. A heat gun or hair drier directed at control connections or attachments one at a time? It might eliminate a lot of disassembly going in??? Then you will know what to fix.

Larry

[Carl Froehlich]

I'd pull both bell cranks, clean out the bearing and re-grease. As already pointed out make sure the bearing is captured by the retaining bolt such that there is no relative motion between the bearing and the bolt - all motion needs to be between the bearing and the bell crank steel tubing.

Carl

[n5lp]

I guess I don't worry enough. Mine has always done this and I just figured it was natural that when the bearing lubricant gets cold the viscosity increases.

[ao.frog]

... for the inputs guys! To heat up one connection at the time with a hair dryer or heatgun is a GREAT idea!
I had never thought of that myself, so thanks alot!

I'll start with one aileron bell-crank at the time, and if that doesn't do anything, I'll check the stick-connections the same way.

Regarding to worry too much: my first -7 didn't have this problem at all. All controls where nice and light all year around. And since I really enjoy the fingertip-feel and the light controlforces of the RV, I want to have that all through the year, not only in the few Norwegian summer months.

Besides; since this is the control-system, I want to find out the cause...

I'll report back after I've checked things out.

BTW: to disconnect my autopilot-servo was a good idea too, but most of the time, she's not hard to move at all, so I think I'll leave her as she is... at least for now...

[Vlad]

I first experienced that aileron stiffness couple days ago at 12,500 feet. Now I know why.