Loose elevator bellcrank Assy?

During the conditional inspection on my Harmon Rocket the elevator bellcrank assy seemed loose with alot of sideways movement. I was looking at the plans on a RV8, it shows two 5702-95-30 washers and two an960-416 washers. Do any rocket builders know if this is the same for the Rocket? Thanks a lot. Video of elevator bell crank. http://youtu.be/HqdAozjL0pI

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The center race of the bearing needs to be clamped between the two supports with spacers or washers to prevent it from rotating, if it's not, then the inner race will rotate around the bolt instead of the bearing rotating.

Loose bellcrank

Thanks Walt for the information. I have read many of your post in this issue with the elevator and stab. I appreciate the education.

Missing spacers and the bolts look like they fit sloppy.

Great camera work!

Nice shot!

Shim the bearing so that the two angle supports are not displaced when you tighten the pivot bolt. Regular washers are fine as shims in this case, as this assy does not rotate side-to-side as a rod end does.

The special washers you mention would be applied at the lower rod end where it attaches to the bellcrank, tho I recall a -060 part number?

BTW the bolt can use a nylock washer, as the bolt does not (should not!) rotate in service. Makes life a bit easier too.

Carry on!
Mark

Someone did not have a set of washer wrenches to install the correct amount of washers in this application...

Loose bellcrank

I went out today and removed the bolt to install some washers. It looked like the bellcrank did not have a bearing for the AN4-13a to go thru. It looked more like a bushing! There was no rotation at all. I was told that this Rocket was built from a old RV4 kit. Does any know if the old RV4's used bushings for the elevator bellcrank instead of bearings? Thanks alot.

floridawing said:

I went out today and removed the bolt to install some washers. It looked like the bellcrank did not have a bearing for the AN4-13a to go thru. It looked more like a bushing! There was no rotation at all. I was told that this Rocket was built from a old RV4 kit. Does any know if the old RV4's used bushings for the elevator bellcrank instead of bearings? Thanks alot.

Click to expand...

So far as I know, RV-4s used BC4W9, BC4W10, or similar 1/4" bore AN218-style bellcrank ball bearings just like the later RVs. That bellcrank is central to the operation of the pitch control system, and the loads on it are such that it really should pivot on a ball bearing.

Looking at the video, it seems to me that there is a lot more play than I've ever seen in any AN218 bellcrank bearing. So I have to wonder if the bearing is full-on knackered, or if maybe the original builder low-bucked it and used a lathe to make a pivot bushing in the shape of an AN218.

Regardless, I think that the solution is the same in any case: Disassemble the bellcrank and install a new BC4W10 bellcrank bearing. They're like $20 from Aircraft Spruce, and probably about the same from Vans:

http://aircraft-spruce.com/menus/ap/bearings_bellcrank.html

Thanks, Bob K.

Loose bellcrank

Thankyou everyone for your inputs. I will remove the elevator bellcrank from the aircraft where I can take a better look at it and find out if it is a bushing or damaged bearing.

REALLY old!!

floridawing said:

I went out today and removed the bolt to install some washers. It looked like the bellcrank did not have a bearing for the AN4-13a to go thru. It looked more like a bushing! There was no rotation at all. I was told that this Rocket was built from a old RV4 kit. Does any know if the old RV4's used bushings for the elevator bellcrank instead of bearings? Thanks alot.

Click to expand...

Yes, you are correct. Get thee a modern bearing to replace this bushing. You might think of getting the parts for a new bellcrank too, just to make sure you have the right parts on hand for assembly.

Carry on!
Mark

Loose Bellcrank

Hello, I ordered a new F-635A elevator bellcrank and VA-146 bearing from Vans for a RV4, I hope that this is the bellcrank used in the HR2. Thankyou for the help!

Can you please post photos of the original bearing or bushing once you get it out? I'd like to see what was actually going on there.

Thanks, Bob K.