View Full Version : TT roll servo installation

09-26-2006, 06:35 PM
Got my TT servo today and started the installation in my 9A. Have a few questions:

1. No instruction on use of the hardware that came with the mounting bracket, i.e., where to put which washers (there are different sizes including two large ones). Any photos of the installation (I did right wing at bellcrank) would be appreciated. I have seen the TT figures.

2. Having installed the servo when I move the bellcrank there is a resistance that I note due to the TT. Is this normal? Is it perceived when flying with the AP disengaged?

3. I realize that safety wires are necessary. The bolts that attach the servo to the spar have holes drilled in the hex heads for safety wire. Any other locations advised? Any photos of safety wire installation (no instructions provided by TT for doing this).

4. What are folks using for wiring? Buying harnesses (kind of pricey at $75)?
DIY? If so any photos from folks who have done this?

As usual, any input will be appreciated. Thanks.

Peter Katz
Charlotte, NC

09-26-2006, 07:35 PM
The servo is a step motor, and you'll feel the resistance as though it's in tiny increments (steps). Once there are airloads on the surface, you won't feel the difference between a servo & no servo.

There are numerous installation pics on these boards, I'm sure someone will have direct links ---- soon!

09-27-2006, 08:12 AM
The slight resistence is normal. When you get the ailerons on and everything ready you won't notice anything.

I wired my own. I'm not a wiring kind of guy, but it was easy. I used the the 5 wire trim wire and a #18 for power and ground. Very simple.

FYI, I mounted my roll servo in the fuselage. Also simple.

09-27-2006, 08:53 AM
SteinAir has servo wire - a pre twisted set of colored wires of the right size which is very convenient (and less expensive than buying individual wires). Crimp on D-Sub pins and stick them in the connector (once the wire is run of course).
The big washers go on the outside of the control rods - the side away from the arm. The idea is that if the bushing fails, the big washer keeps the rod from falling off (the rod end is captured between the control arm and the washer) . I don't have a picture handy.
You get to figure out how you want to do the safety wiring :rolleyes: I haven't yet decided if it is easier to run the wire from bolt to bolt, or drill a hole in the mount for each bolt.

09-27-2006, 10:44 AM
I don't have the roll servo installed yet, but here's my pitch servo:


The safety wire was easy compared to some spots on the engine. It's a good place to practice.

Jim P
09-27-2006, 11:57 AM
Darwin, do you have any pics of the fuelage mount for your roll servo?


09-28-2006, 08:09 AM
Hi Jim,

I'll see if I can find them.

10-23-2006, 11:24 AM
Just to complete the story, here's a picture of my wing servo install:

I assembled (almost) everything on the bench, and then installed it in the wing after riveting the bottom skins.

Doing the safety wire for the servo mount bolts would have been much easier on the bench.

I used the alignment jig for the bellcrank to adjust the length of the servo pushrod until the servo arm was at 90 degrees.

12-09-2006, 09:31 AM
I got my TT Roll Servo bracket for Rt wing and was confused until I discovered they had sent me the bracket for the LEFT wing...

Does anyone have pics of their installation in the rt wing of a -9? Also, is it correct that you are supposed to use the WD421-L bellcrank assembly for the Right wing?

12-09-2006, 11:38 AM
Would somebody please post a list of the bolt sizes required for the TruTrak wing leveler.

12-09-2006, 03:39 PM
My install, I did not use the large washer on the pushrod as others.

12-11-2006, 06:54 AM
Would somebody please post a list of the bolt sizes required for the TruTrak wing leveler.

This is the packaging list as supplied by TT. It had a couple of slightly longer bolts than those supplied by Vans.

Here is how my bracket install looks...minus the support bracket.