Aileron Bellcrank Installation

[longranger]

When I tightened up the pivot bolt to clamp the aileron bellcrank bushing between one set of my aileron brackets, the bellcrank felt like it was binding; not much but enough that I could put the bellcrank in any position and it would stay there. I did grind the bushing to length and I have about 0.020 - 0.025" clearance between the end of the bellcrank pivot and bracket with the pivot bolt tightened.

The instructions say you have to ream the bushing for a slip fit on the bolt. My bushing came with hole already a slip fit on the bolt, but the bushing in the bellcrank is a light tap fit. Should I ream the bellcrank pivot hole, or allow the bushing to "wear in"? I did lubricate the bushing with molybdenum grease before installation.

[bret]

yes, clean up all powdercoat slag on the inside of the bell crank, the bellcrank pivots around the locked in bushing, via the clamp force of the bolt. and your bushing is longer than the bell crank right? .010" - .020"

[longranger]

Originally Posted by bret

yes, clean up all powdercoat slag on the inside of the bell crank, the bellcrank pivots around the locked in bushing, via the clamp force of the bolt. and your bushing is longer than the bell crank right? .010" - .020"

Yes, I've cleaned up the powdercoat on/in the ends of the bellcrank, ground them flat and square on the belt sander, and ground the bushings to length. Measuring by Mark I eyeball, I have 20 -25 mils clearance between the bellcrank and bracket with the bushing clamped down. I'm thinking there might be slight bumps inside the bellcrank pivot hole where the arms are welded on.

[DaAV8R]

I ran into this same issue. The bellcrank ran smooth on the bench but not when installed on the spar.

I removed the brackets from the wing and assembled the brackets, bushing, bellcrank and bolt on the bench. I checked center to center of the bracket holes with the assembly "at rest" and it did not match the hole spacing of the wing spar. When installed on the wing the bolt would pull the bracket ears to the bushing but in doing so it apparently created some side load on the bushing/bolt. This was causing my dragging.

I did a little shimming between the center bushing and the bracket and the problem went away. Smooth as butta

[alpinelakespilot2000]

One thing to try that I needed to do: Tape some sandpaper to a dowel rod. Chuck it into your drill and run it inside the bell crank to smooth out any rough spots.

[longranger]

Originally Posted by alpinelakespilot2000

One thing to try that I needed to do: Tape some sandpaper to a dowel rod. Chuck it into your drill and run it inside the bell crank to smooth out any rough spots.

Thanks Steve, I'll give that a try. I also have a 0.374 reamer if that doesn't work.

[longranger]

Tonight I futzed around some more trying to get the right aileron bellcrank to work better. It operates the same whether the brackets are bolted to the spar or sitting loose on the bench, so I don't think there's an alignment problem. Also, if you look closely in the first photo you can see that the bushing is sufficiently longer than the bellcrank, so it's not binding at the brackets.


Removing the bushing from the bellcrank, I noticed a series of shiny bands on the bushing where I assume the bellcrank is dragging on the bushing. I rigged up a stack of washers and a jam nut on the pivot bolt so I could chuck the bushing in my drill press for polishing without the chuck marking it up. This helped a little, but I never could get the bushing chucked up squarely again for a second round.


I couldn't come up with a dowel of sufficient size to try Steve's suggestion, so ran my 0.374 reamer through the bellcrank, but I couldn't really tell that it made any difference. The bushing measures out right at 0.375, so I didn't really expect a lot.

What did help was turning the bushing around in the bellcrank. I guess that orientation more closely aligns the irregularities on the bushing with the irregularities in the bellcrank. The bellcrank operates MUCH better now, but there's still room for improvement. I think the next thing I'll try (tomorrow) is to clean all the grease off/out of the parts, reassemble them, and spin the bellcrank around the bushing to "remark" the high spots on the bushing, then clamp it crosswise in my vise and use a bit of "shoeshine" action with strips of sanding belt and scotchbrite to work them down. I'll make every effort to go at this easy in an attempt to not make the bushing too sloppy.

[hydroguy2]

Originally Posted by longranger

.......... think the next thing I'll try (tomorrow) is to clean all the grease off/out of the parts, reassemble them, and spin the bellcrank around the bushing to "remark" the high spots on the bushing, then clamp it crosswise in my vise and use a bit of "shoeshine" action with strips of sanding belt and scotchbrite to work them down. I'll make every effort to go at this easy in an attempt to not make the bushing too sloppy.

You're removing material from the wrong component. Your problem lies within the bellcrank. Smooth out that and you'll be golden

[MauiLvrs]

We had a similar issue and Vans had to send us a new aileron bellcrank.

[Arie]

I used a butcher knife sharpner, the round rod type, if you know what I mean. Mine fited the hole in the bellcrank perfectly ,and after a few turns of the sharpner in the hole all the high spots were removed and the bushing slides in like it is oiled. This might help, but I doudt the butcher knife sharpners are an international standard regarding the rod diameter.LOL