Bellcrank bracket attachment

odlee · #1 02-12-2007, 07:51 AM

On one side of my -7, the bellcrank bracket binds whenever the AN4-32A bolt is torqued to spec, both the high and low values. The bracket and brass bushing are both burr free and everything moves freely until the last bit of torque has been applied. Appears to be either a slight deformation of the bracket or the brass bushing hole may be slightly off center. In lieu of reordering bracket and bushing, does any one see a problem with going to a drilled AN4-32 bolt and using a castellated nut with cotter pin. The bushing will be held firmly enough to allow the bellcrank bracket to move freely on the brass bushing as per Van's design. I intend to run this by Van's tech group also.
Thanks, David

IowaRV9Dreamer · #2 02-12-2007, 09:12 AM

I haven't yet attached my bellcrank but it is coming soon, maybe some experts can help me?

It looks like the design is such that the bushing is to be trimmed so that it is slightly longer than the bellcrank, so that when the bolt is tightened the bushing is captured between the brackets. This would leave the bellcrank free to rotate on the bushing. The bushing doesn't rotate, right?

I have to ream out the inside of the bushing for the bolt (1/4 inch??). What is the best way to do this? I have a 0.250 inch reamer that I could put in the drill press but how to I hold the bushing? I saw someone wrapped it in duct tape and held it with pliers.

Also, what is the best way to trim / cleanup the bushing?

Thanks in advance,

cjensen · #3 02-12-2007, 09:36 AM

The bushing should stick out just slightly from the bellcrank, and you're correct, it does rotate about the bushing. The bushing does need to be reemed to 1/4" for the AN4 bolt. I put the bushing in a vice (with appropriate padding), and drilled. The bushing needs to be secure for a straight hole. I sure couldn't do it with a pair or pliers holding it.

Then I put the bushing in my drill press to smooth the OD with scotchbrite.

cytoxin · #4 02-12-2007, 09:39 AM

i would uses a castelated nut with a fiber lock insert as a secondary safety.
http://www.aircraftspruce.com/catalo...es/ms17825.php
but dont let the bolt turn in the hole when in use.

MS17825 Self-Locking Castle Nuts

Manufactured to standard castle or shear nut specifications with a nylon insert added for positive safety. Use it throughout the control system. Should the cotter pin used with castle nuts be over looked you will still have a safety...

cytoxin · #5 02-12-2007, 11:00 AM

inside this weldment the tube has bumps from the welding on of the levers. this is what hangs on the brass bushing. polish this out before changing methods. or you'll likely end up with the same result.

IowaRV9Dreamer · #6 02-12-2007, 11:02 AM

Quote:

Originally Posted by cjensen

I put the bushing in a vice (with appropriate padding), and drilled. The bushing needs to be secure for a straight hole. I sure couldn't do it with a pair or pliers holding it.

Then I put the bushing in my drill press to smooth the OD with scotchbrite.

Did you just use a hand drill with a reamer or did you try to align the vice under the drill?

Thanks for your help - I think I'm obsessing about this bushing!!

dave

odlee · #7 02-12-2007, 11:43 AM

Thanks guys,

I have about decided to continue with the emery cloth/dowel method I was using on the bellcrank tube. I do not want to do any more to the brass bushing. In discussing with Van's tech support. Ken (Don't know which one.) stated the tube moves during the welding process(obviously) and almost always causes some disstortion in the tube. Either a reamer or other methods such as my emery cloth/dowel will open it up enough to allow the the bracket to rotate. The bracket does not have to move 180 degrees so even binding may be present without affecting control movement. Probably need to obsess more after the aileron is attached rather than before. As long as the bracket rotates on the bushing, not the bushing on the bolt everything should be ok.

cjensen · #8 02-12-2007, 12:43 PM

Quote:

Originally Posted by IowaRV9Dreamer

Did you just use a hand drill with a reamer or did you try to align the vice under the drill?

Thanks for your help - I think I'm obsessing about this bushing!!

dave

Yup, a hand drill with the bushing in the vise. I obsessed about it at first too. After the first one, it's no biggie. Much easier than I thought it was going to be. Once it is started square, it really has no place to go but straight in to the bushing. Just make sure to get it going square to begin with.

Get used to it...there are several more that need to be done in the fuse kit.

flydjd · #9 02-13-2007, 02:58 AM

Quote:

Originally Posted by IowaRV9Dreamer

I haven't yet attached my bellcrank but it is coming soon, maybe some experts can help me?

I have to ream out the inside of the bushing for the bolt (1/4 inch??). What is the best way to do this? I have a 0.250 inch reamer that I could put in the drill press but how to I hold the bushing? I saw someone wrapped it in duct tape and held it with pliers.

Hi Dave,

I am FAR from being an expert ...but after clamping my bushing in the vice on my upright drill and trying to do this by eye ( and ordering a new bushing from Vans

) I ended up getting a metal rod from the local hardware store which matched the " before " I.D.
I fitted this in the drill and used it to line everything up in the vise and then replaced it with the 1/4" drill ....... worked OK for me...

But why can't Vans just source these bushings with the correct 1/4" I.D. ???? They must be enough numbers involved OR maybe drilling these out just tips all builders over the 51 %.......

RVbySDI · #10 02-13-2007, 07:34 AM

Quote:

Originally Posted by flydjd

maybe drilling these out just tips all builders over the 51 %.......

This would be a far stretch for me to believe. There is far more building to these RV's than I ever even came close to on my previous built experimental aircraft.

My understanding of the rule is that it is not about the idea that we have to build 51% of everything that has to be done to build an airplane. It refers to the fact that the builder does 51% of the tasks. In other words, if you have to construct 50 ribs for the wings, if you build one of the ribs and then have the factory build the rest you have proven that you have worked on that one task of building a rib. As long as you do so with all the other tasks up to and exceeding 51% of the needed tasks then you comply with the rule.