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routing Ray Allen Trim servo wires

simatos

Well Known Member
what is a safe way to get the servo wires from the elevator to the Horizontal stab??? Thanks Gary
 
I used D-sub pins and sockets staggered to make the trim servo removable.
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Cover the now connected wiring with some expandable sleeving and heat shrink.
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The hole on the elevator spar that the wiring goes through also conflicts with the threaded rod that sticks out on the servo. I drilled a smaller hole above that large hole big enough for a small snap bushing sized for the sleeved wiring. I made the new hole close enough to the existing hole so I could cut a small slot between the two holes so that the servo wire could be slipped into the new hole from the existing larger hole.

Picture this (rotated 90 degrees):

o=O

(crude ASCII drawing representation of big hole and small hole connected by a small slot)

Simply slit the small snap bushing with a utility knife so you can install it over the servo wire then snap it into place in the new smaller hole you drilled. The snap bushing fills the new hole and the slot is small enough to not affect the stability of the snap bushing to stay in the wiring hole.

Once you get the servo installed in the elevator, you can pull the wiring back into the fuselage and make a service loop there for the excess wire.
 
Bruce Thanks, So it is normal for the jack screw to go thru the elevator spar?
I have the Ray Allen servo T3-12A form Vans. I was starting to wonder if it might be too big, it travel is 1.2 inches. Plans refer to servo "ES-MSTS-BA" Right now i have the servo way too close to the spar and it is even difficult to fish the wires thru there with out squashing them and of course there is no room for the jack screw to go to the end of its forward travel as it hits the spar.
 
If you are using Van's electric trim install kit, the position of the Ray Allen Servo should be fine. I don't think the jack screw moves fore and aft, it just rotates in the unit and moves the linkage to the trim tab. It shouldn't be hitting any part of the elevator.
 
Actually it does screw out the one end of the servo box over an inch. The servo neeeds to go back the same one inch to allow full range of travel. I like the way you prepared the wires to go back to the tail cone. Thanks G
 
Wires

Hello Bruce,

I am a young homebuilder and electricity is very new for me. Can you tell me which D sub pins you used and the socket staggered too ? if you have a link to by them?
In advance thank you

Sylvain
 
I would recommend cannon plugs instead of D-subs. The best source I have found is Mouser. Here is the data sheet for Amphenol connectors, which has a bewildering array of info: http://www.mouser.com/ds/2/18/inhouse_Amphenol_DTL-5015_connectors-183710.pdf. In my RV-10 I use straight connectors in the 14-5 insert arrangement. They also have what they call 'box mount', which I have always referred to as 'bulkhead', connectors, which I am using for my wing-to-fuselage connections and on my firewall, obviously with a larger number of insert connections. But you might find a use for them in the tail.

I prefer cannon plugs for several reasons. More secure connection, the inserts often seal better against contamination, and the bulkhead connectors make one-handed connections easier in hard to reach places. Nothing against D-subs except I swear at them every time I have to get a screwdriver into a hard to reach place. In fact, they are cheap and reliable.
 
Sylvain,

What Gil said! I got my milspec D-sub pins and sockets from Steinair. Very easy to install and crimp onto the wires, then put some heat shrink tubing over the connections to hold them in place. No need to have any connector body taking up space in this spot.
 
Mark: Agreed: Powered up the servo while installed in the elevator and extension of jack screw bangs up against the spar so to make it work it work, the screw needs to go thru the spar or the servo must be mounted about one inch further away from spar. Thats where I am now, considering the reposition of the servo further away and see if that position works the trim tab ok. While there is a hole in the spar where you can route the wires, it is not in line with the jack screw as I have it all built. You need to run the servo thru its entire range to make sure there is no jack screw conflict, other wise I think you could
"SCREW" up the screw and servo big time, Thanks for your help, Cheers G
 
The hole on the elevator spar that the wiring goes through also conflicts with the threaded rod that sticks out on the servo. I drilled a smaller hole above that large hole big enough for a small snap bushing sized for the sleeved wiring. I made the new hole close enough to the existing hole so I could cut a small slot between the two holes so that the servo wire could be slipped into the new hole from the existing larger hole.

Picture this (rotated 90 degrees):

o=O

(crude ASCII drawing representation of big hole and small hole connected by a small slot)

Simply slit the small snap bushing with a utility knife so you can install it over the servo wire then snap it into place in the new smaller hole you drilled. The snap bushing fills the new hole and the slot is small enough to not affect the stability of the snap bushing to stay in the wiring hole.

Once you get the servo installed in the elevator, you can pull the wiring back into the fuselage and make a service loop there for the excess wire.

Is Bruce's solution still the most accepted way of making this modification? There's no way I'm comfortable with the Jack screw and wire running through the same hole like the standard drawings suggest. Does anyone know Vans take on this mod?
Tom.
 
I just did exactly what Bruce suggested. It looks like it will work great and Bruce isn't having any issues and he is flying the pants off his plane.
 
I did the same as Bruce, following AeroElectric guidelines. Be sure to use a good heat shrink that won't allow the pins to be pulled out after shrinking.
 
Wire routing feedback from Van's

I wrote to Vans on this figure eight hole and received a response from them this morning regarding it and a number of other wire routing holes. They (Scott and Sterling) were not happy with the figure 8 type hole configuration in the elevator spar, but were satisfied with drilling another completely separate 3/8" hole approximately halfway between the edge of the existing hole and the top of the spar so that you don't have to route the cable through the same hole as the jack screw. This would mean terminating the cables in a plug after they had been routed, or possibly using small staggered bullet type joiners you could feed through one at a time (someone elses post addresses this on the forum). I'm not here to tell anyone they can't use the figure 8 hole in this location, I'm just saying that two of Van's tech guys were saying it was unacceptable, so I would think that if you are insistent to use it, perform your own fatigue and stress analysis. Regarding the rest of the routing of the trim cable, I had proposed feeding this along the front of the elevator torque tube per the plans, then down through a hole and corresponding snap bushing in the F-714 aft deck just in front of the elevator torque tube. The cable would then feed into conduit centered on the webs of F-711 and F-710. This hole would be 9/16" in size for the conduit I am using. From here the conduit would feed forward all the way to just aft of the main spar carry through. If necessary, a standoff with adel clamp would be riveted to the left side skin to hold the cable away from the elevator horn after it passes through the F-714 and into the conduit. My postings on the conduit may be found below.
Although my setup is relatively simple (only an electric elevator trim and rudder tail light) hopefully this helps others with similar wire routing questions.
Tom.

Fuselage Conduit Thread:
http://www.vansairforce.com/community/showthread.php?p=1120336#post1120336

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Simple solution

http://www.vansairforce.com/community/showthread.php?t=114651
FP04012013A000MN.jpg

The solution in the link above seems far more elegant than the one I ran past Van's. I can't believe I didn't find it earlier. It keeps the wiring well away from the screw jack and makes the hole in an already reinforce location on the elevator. The routing up and over the spar also means you do not have the risk of water running down the cable into your connector as I did. The only thing I don't like is the fact that you've got to remove the HS bolt to remove the plug. I've reamed my bolt holes to a relatively tight tolerance in this location, so it's not something I'll want to be pulling out. I'll think of some way around this.

Tom.
 
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Ray Allen Trim Servo wires

Please click on the links below for a view of the system I have used. I joined the short wires exiting from the elevator initially with D-Subs and then used a 9 pin connector to enable easy removal of the elevator.

The wiring length after the P-Clamps allows sufficient movement without the wire contacting against any part of the aircraft.

Hint: In the initial joining of the harnesses use differing lengths so that the joins are not all at the same location to minimise wiring thickness at the join location.

https://www.flickr.com/photos/141779426@N07/36778987024

https://www.flickr.com/photos/141779426@N07/37488428081
 
servo wiring

The wiring length after the P-Clamps allows sufficient movement without the wire contacting against any part of the aircraft.
That's pretty clever. I've already done mine differently, but since I'm in the middle of the hstab SB, I might reconsider.
 
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