Elevator Trim Tabs

[ten4teg]

I need some technical help. I installed the trim servo in the
empennage to test it out. I followed all the directions in section
11-9 and 11-10. I ran the servo to the full "nose up" position as
stated and set the trim tabs down deflection for 35 degrees.
However, when I ran the servo to the full "nose down" position there was
hardly any trim tab up delection. The right side had some up deflection,
but the left side had none. It appears there is not enough travel in the
servo and related cables. Also, because of the F-1095B Bellcrank
(one cable ahead of the other) when you run the servo to the full "nose
down" position, the left cable stops advancing when it gets close to
the F-1095A Trim Mount Bracket and actually starts to shorten
when it goes below the F-1095A Trim Mount Bracket while the right side
cable keeps advancing. So, you end up with the two trim tabs in different
positions. It looks like the servo should be limited in the nose down
direction so the two cables always advance the same. What
should the trim tab up deflection be? It is not stated in the manual. Looking for help from anybody that can explain this. Thanks, Tom

[Mel]

The anomoly you are seeing is normal. I've inspected quite a few -10s and each one is slightly different, but the anomoly is always there. The separate trim tabs on the -10 were originally intended to operate individually. One tab was to be for normal trim and the other was to be attached to the flaps for automatic compensation. This system did not work out the way Van intended so it was abandoned. At least this is the way I understand it. As long as the tabs don't contradict each other (one up and the other down), you should be ok.

[cstanley]

Mel:

You have no idea how much your post calmed my nerves. I saw the same problem, made a note and figured I'd deal w/ it during re-assembly. You saved me a number of frustrating hours that would have come to no good anyway.

Thanks.

[dmaib]

We wrestled with our elevator trim assembly all day today and when it was installed, we could only get the clevis adjusted to provide 30 degrees of down tab on the right and about 25 degrees on the left. What have we done wrong here? Followed the 11-9 and 11-10 instructions very carefully.
The only thing I can think to do at this point is to adjust the MW-3M rod end bearings so the cable is threaded further into the rod ends. Does that make sense?
I don't look forward to threading those cables back into the stabilizer once or twice more!
I am also concerned about the oval shaped hole where the trim cable first enters the stabilizer. I see no mention of any kind of bushing type material to keep from wearing the cable. What are people doing about that?

[hsdexo]

I pulled my system back off the airplane and made sure every thing was fabricated correctly then re-installed it.
You can get the 35 degree nose up trim by adjusting the length of the cables through the nut welded to the cover plate.
Nose down trim, only the starboard trim tab will rotate up the port side stops just above the neutral position.
This is all proper installation.
After I intalled the one on my RV10 the second time I called Vans and they confirmed it was correct.
I did tell them they needed to add a note to the construction manual to advise this as proper rigging.

Harry

[John K]

Hole bushing material - I used MS-21266 available from Avery per the AC 43.13-1B & 2A.

[Mike S]

Just in case you may have missed it, there was a problem with the cable end mounts a while back.

Vans issued a SB, http://www.vansaircraft.com/pdf/sb06-9-20.pdf on this.

In addition, there is a guy making a really nice replacement part, at http://www.rivethead-aero.com/rv10_005.htm

Mike