Stiff (very) Elevator

[BRS]

Today during preflight I thought the elevator seemed a bit stiff. After a short flight I decided it's actually quite stiff and terminated the flight. Upon instigation I found that the 'horn' between the push tubes (photo below) was so stiff I could hardly move it. Although the plane has been hangared it's been quite warm and humid. I'm guessing the shaft decided to rust. So much so that I was not even able to remove it - yet. The shaft seems frozen in the horn but the shaft moves in the airframe. The bubbles in the photo are penetrating oil.

Has anyone seen this happen before?

[User GDS]

It looks like your bellcrank is pivoting on a piece of steel tubing, I'm pretty sure mine pivots on an AN bolt. I don't remember if there is a bushing or not, but the cadmium plating on the bolt will inhibit corrosion.

[jak]

Query this forum and you'll find where I posted quite some time ago this bushing you have should have been replaced with a an6-40 bolt. This is a part you should remove and inspect and regrease each annual. Jak

[SheepdogRD]

Here's a link to the thread Jak referenced: http://www.wingsforum.com/viewtopic.php?f=218&t=18267.

[BRS]

Thanks for the input! I knew I could get good info here.
Yes, as soon as I saw (I'm the second owner) 4130 tube in 4130 tube it was easy to see that something was going to eventually happen.

On another note. This bell-crank looks rather labor intensive to build. Seems it would be much easier to fabricate from square tubing just larger than the round tubing for the shaft. This would eliminate the welds on the ends. Just drill the square tube, slide in the round tube and weld. The notch the ends.

[Trilander Ted]

I drill out the correct A/N bolt on the lathe down (length wise) then put an exit hole (cross wise) and tap a grease zerk thread on the hex end of bolt. Naturaly, the exit hole should be located close to the center of the bellcrank. That way, all you need for condition inspection is a shop towel and a hand grease gun plus a light. That's one of the things I would add to the kit, or at least recommend it. I found it difficult to reach through my trap door and disassemble then reassemble serious parts while on my hands and knees. Hope this helps. Ted

[Johnny C!]

Great idea!

John

I drill out the correct A/N bolt on the lathe down (length wise) then put an exit hole (cross wise) and tap a grease zerk thread on the hex end of bolt. Naturaly, the exit hole should be located close to the center of the bellcrank. That way, all you need for condition inspection is a shop towel and a hand grease gun plus a light. That's one of the things I would add to the kit, or at least recommend it. I found it difficult to reach through my trap door and disassemble then reassemble serious parts while on my hands and knees. Hope this helps. Ted

[Doug Baird]

Here is the reference to a post I did in 2009 addressing this issue.
Fri Sep 25, 2009 7:03 am

I have made a modification as indicated above to the bellcrank bushing.
The first photo shows the installation of the bushing before drilling and riveting.
I was concerned that there was no lubrication on this and, as can be seen from the photo, the bellcrank had a quarter inch of sideways play.

The second photo shows a modified bushing with 1/16" weep holes drilled, the ends tapped with a cap in one end and a zerk fitting in the other plus two .0125" nylon washers punched to the size of the bushing.

Photo three shows the bushing (with a 90 degree zerk fitting) and washers installed.

Image

Image

Image

[alan]

Ted,

Thank you very much for the idea of the grease zerk fitted bolt. I made one the other day and installed it today. This is a great idea and it should work well for the life of the airplane.

Alan

[Johnny C!]

What are you going to sell
those for?

John

Ted,

Thank you very much for the idea of the grease zerk fitted bolt. I made one the other day and installed it today. This is a great idea and it should work well for the life of the airplane.

Alan

[Clark in AZ]

Old thread, looking for some pics. Anyone have pics of how to install this grease zerk mod? Unfortunately, some of the pics in the thread have disappeared.

This sounds like a worthwhile mod and I'm at the perfect point in my build to do it.

Thanks,
Clark

[GreggC]

I drill out the correct A/N bolt on the lathe down (length wise) then put an exit hole (cross wise) and tap a grease zerk thread on the hex end of bolt. Naturaly, the exit hole should be located close to the center of the bellcrank. That way, all you need for condition inspection is a shop towel and a hand grease gun plus a light. That's one of the things I would add to the kit, or at least recommend it. I found it difficult to reach through my trap door and disassemble then reassemble serious parts while on my hands and knees. Hope this helps. Ted

Any concern that drilling the center of the bolt will weaken it ??
Brilliant idea, just wondering about strength.

[SheepdogRD]

Unfortunately, some of the pics in the thread have disappeared.

Luckily, I saved Doug Baird's pictures back when they were first published.

Elevator Bushing - Doug Baird 1.JPG

Elevator Bushing - Doug Baird 2.JPG

Elevator Bushing - Doug Baird 3.JPG

[Clark in AZ]

Excellent! Thanks much, I now have them saved as well...

Clark