Separate yoke from column

[Rodney]

If anyone has separated the yoke from a column on a real aircraft I have a question or two. 1. Is the inner hub clean or have adhesive?
2. Is it keyed?

I pulled the 4 screws from the shaft, it rotates and comes up out of the column about 3/4". Not high enough to see inside the hub.

Thanks in advance.

[RadarBob]

I haven't actually removed a column from the aircraft, but I have some of the the parts here, so I may be able to help:

The horizontal bearing/bevel gear assy is removed by unscrewing the hex key in the rear of the column top casting (carefully as the hex bolt is made of some light alloy) and tapping out.

The bearing is push fit into the column top casting.

Removing the column top casting from the column outer casing may be more difficult - I think it has to be removed from the bottom of the column.

The one I have here had been cut off about 5" below those 4 screws. If you look up the cut end towards the column top, there is an inner alloy tube that links to the vertical bevel gear. It is fixed with some kind of castellated ring to the vertical bearing/gear.

There is also a larger outer castellated ring that appears to hold the whole vertical bevel gear/bearing assy in place. I cannot get those out of my column top as I don't have the correct wrench, and it has been wet and corroded in.

It doesn't look badly corroded, but enough to seize it anyway.

I thought I would leave it and fix my pot to the inner tube.

It appears that the column top cannot be pulled from the outer column casing
unless the inner tube is first released at the column bottom.

I have seen pictures of the column bottom/cross-linkage, and it looks to me like there is a 90deg bend to the right (in the captains case), and there may be some kind of inspection cover there where it can be released.

APHS had some photo's of this at one time but I don't think they are there now. They do have a picture of the horizontal bevel gear assy on there though.

Hope this is of some use - I would post some pics but I don't have a camera here - Can borrow one though if you think it would help.

Best Regards,

Rob

[RadarBob]

Looking at your photo more carefully Rodney, I can see that you have removed the hex bolt and the nut so it looks to me as if the yoke itself should just pull/tap off the splines in the hub assy now.

Rob

[Rodney]

Thanks Rob! Got them off. Now to clean and powder coat.

[RadarBob]

Good news - Glad it worked out ok !

How did it all come apart in the end, and did you manage to get the column
out complete ?

Rob

[Rodney]

The FO shaft was corroded. So I tried the Capt side and it slid right off. Used a rubber mallet on the FO side. Tried a puller but it would not hold long enough to start it to move. I don't think I'll take the columns out, rather just paint in place.

[RadarBob]

I guess there is a lot of work involved in removing it - So as you say, probably best to paint it in situ if you can.

Look forward to hearing how it all progresses.

All the Best,

Rob

[Michael Carter]

Nick at APHS has a source that re-dips these yokes after bead blasting off the old finish. I don't know the price, but it probably isn't cheap.

IF you can get him to answer his e-mail he might be able to steer you to the guy.

He still has not answered two more e-mails I've sent to the address listed on the site.

[Rodney]

Thanks Michael! I have an evening this week at friends house with a bead-blasting cabinet. There are a couple of places in town that do powder coating, seen work from one. I am just amazed at some of the depth of nicks in these. Like they were used as foot rests. Oh and not to mention that some of the FO's were slobs. Food particles all over the column and foot area's.

[Michael Carter]

Well, they're not originally powder coated. They are dipped in urethane and left to dry. Similar to a bowling ball.

[Gsey]

The way that I found easiest to remove the original coating was to put them in an oven on low heat and use the heat to soften the material before scraping it off with a sharp razor. Then hit with sandblaster before powdercoating.

I tried using a sandbalster first but it took ages to make any impact on the coating so tried the oven and it seemed to work.

Gary

[LH784]

Hi Rodney,

there is a wealth of information on this link including drawings in the downloads section (7x7 old style):

http://www.project777.com/?mid=2042

Greetings, Florian

[Rodney]

Thanks Florian. Some good info on that site. Nice to see some pdf's on components too.

[capt_tom]

Hello,

i want to come up with this thread. I have a similar problem. So I want the change the side of the control column so that the F/O Column can be used of the Capt side. Nick from APHS told my that after removing the 4 phillips screws of the top the head part can be turn 180 °.

Did anyone have experiences with that procedure? Are there some issue to have a special look on? Did somebody have pictures or docs according the inner structure of the column in addition to the informations form projet777?

Hopefully somebody can help me!

Thank you

[capt_tom]

Guys, I did it for myself. It is relativly easy. The different steps are:

1. Removing the 4 phillips screws at the top of the column.

http://s7.directupload.net/images/120423/3gv4bqy3.jpg

2. Yanking out the inner shaft from the bottom side.

http://s14.directupload.net/images/120423/gek56e4f.jpg

The disassmbled assy looks as follows:

http://s7.directupload.net/images/120423/zxm4khk5.jpg

Important note: Do not turn the head before completly removed. The inner thread inserts can be damaged by the inner wire channel.

See the next picture for the inner thread inserts within the head part.

http://s14.directupload.net/images/120423/kl5finsf.jpg

For changing form F/O to CPT or vice versa the head part needs to be mounted in the column turnd by 180 °. Additionally the inner wire channel (shown in the next picture) needs to the mounted of the opposite side of the column.

http://s7.directupload.net/images/120423/5v4yuhsr.jpg

[bas_v]

Kudos to you for sharing the answer after you found the solution.