The Cessna 120-140 Association Forum

Does anyone have a source for the P/N S15-50 Bushings used at both ends of the elevator trim tab actuator rod? I'm finding them at about $200 each, which seems insane even by aviation standards. It's not like they're going on a Bonanza.

It's been that way for at least 30 years. I ended up making a pair.

Thanks for the info, John. I was afraid of that. Is there something non-standard about the material or dimensions that makes them so pricey? Unobtainium-plated unicorn horn perhaps?

6478 wrote: ↑Mon Aug 03, 2020 8:19 pm Is there something non-standard about the material or dimensions that makes them so pricey?

Nope! Standard steel bushing material. It's a manufacturer's part number, S15-50. I researched it once but don't recall what I found, other than it was off the shelf in 1945. I may have some dimensions around somewhere.

Thank you again John! If the dimensions are easily available that would be great, but don't put much effort into looking. I should be able to measure the current bushings and figure it out.

Question about elevator tab bushing:

Does the elevator tab horn get drilled to accept the outside diameter of the bushing, and the bushing run through the tab and actuator end? My NOS trim tab is drilled for an AN3 bolt, and I'd have to drill it larger to accept the bushing (making the bushing run through tab horn and actuator end). This seems better engineering as there will be no steel-to-aluminum wear on the elevator tab

Alternatively, I would spread the tab's horn a little and fit around the bushing.

But it seems like Cessna would have pre-drilled the horn holes to accept the bushing diameter if they wanted it that way?

Jon

The bushing should be captive so that it does not rotate on the bolt, That way the wear is between the bushing and pushrod, not the aluminum horn. (Same thing with the rudder hinges...)

I just found some play in my trim tab and noticed that instead of an AN3 bolt and bushing, I have an AN4 sans bushing.

Anyone have a length on the bushing? An OD would help too but I'm gonna make a set to match AN4 dimension.

Try calling Univair. I remember getting sticker shock when I saw the price, but when I called Univair, they weren't nearly as expensive.

If the AN-4 bolt fits in there then the holes on the trim tab bracket are enlarged. The purpose of the bushing is to provide a surface that doesn't rotate as it is captured between the two ears of the bracket.

IIRC, the dimensions are 0.510 long and nominally 0.250 diameter. Material is steel. It has to be slightly longer than the width of the control rod fork and the diameter is a loose fit in the holes of the fork.