control column length/ AVION instrument panel

simatos · Post by **simatos** » Mon Nov 28, 2005 8:01 pm

I saw some recent discussion on the Avion instrument panel which allows placement of avionics in the center of the panel. I have this in my plane and with the control yokes/columns in place they seem to stick out from the panel quite a bit farther than I would have expected. The travel is not quite as far forward either. I seem to recall the stock control column assemble came very near thew firewall in the full forward position while my set up in full forward position is a good 4 inches from the firewall with the elevator in the full down position if you can follow what i am saying. Well since ther are at least a couple of you Avion panel guys out there I wonder if you encountered this situation also. I will lookforward to your comments , Gary.

blueldr · Post by **blueldr** » Mon Nov 28, 2005 9:46 pm

All stock C-170 series airplanes have a "T" yoke as built. This yoke precludes center stacking the radios due to the shape of the yoke behind the panel. To modify the airplane requires the removal of the "T" yoke and installation of a "U" yoke from an early C-172 or a modified "U" yoke from some other Cessna model. This used to be done on a 337 with a field approval, but with the present attitude of the FAA this may no longer be possible. I do not know if there is a STC available foir this modification. You might check with Del-Air in Porterville, CA.

simatos · Post by **simatos** » Tue Nov 29, 2005 2:10 am

My new AVION set up have the 'U' shaped yoke opening up the central area behind the pannel for radios, just seems to me the position of the control columns is further back than with the original stock set up as described above. I wonder if the Avion set up needs to have shortewr columns to work// I will consult the documentation and get back to ya thanks G

Post by **GAHorn** » Tue Nov 29, 2005 2:46 am

Gary, is it possible that your cables are not properly adjusted? (Or that incorrect cables of insufficient length are installed?) In other words, if your cables are adjusted such that the elevator is down against the stops, yet the control column is not travelling sufficiently forward (behind the panel), ...then perhaps the total amount of travel of that control column is not being reached. This might explain why the column strikes the radios (and/or why the radios are mounted to protrude into the cabin...so the column can travel further aft.)
I don't have direct experience with this setup, but I can imagine the situation such that total travel of the column is limited because of incorrect cableing.

c170b53 · Post by **c170b53** » Tue Nov 29, 2005 4:41 am

The U control column is shorter than the T, which means it doesn't have to travel as far for the cables to hit the stops on the elevator bellcrank. And in being shorter in some cases allows the instruments to be placed in a standard "T".

simatos · Post by **simatos** » Tue Nov 29, 2005 4:55 am

Thanks you guys, I have a hangar day tomorrow and will check it all out. The U shaped yolk give lots of room for radios, there is no conflict with anything under the panel. Thanks g

lcranton · Post by **lcranton** » Thu Dec 01, 2005 2:57 am

Gary, I have done a couple DELAIR center stack panels however I am not familiar with the Avion setup. The DELAIR uses splices the upper portion of a donor C172 U column to the bottom 5 inches of the stock C170 column. This allows the portion of the column from the pivot point to the elevator push rod to be the correct length. The later C172 column has a bend in the vertical tubing and thus moves the upper control shaft universal joints/sprockets to a different position in the longitudinal axis. When installing this mod the rigging of the elevator system is important in order to obtain proper elevator travel (contacting the elevator stops with the aft bellcrank without contacting the panel/instruments, firewall or the fwd bellcrank/tunnel structure first). You may want to check your elevator up/down angles and verify they meet the TCDS travel specifications. As George mentioned the elevator cables need to be installed in the correct positions (Up/Down cables) and it may be necessary to walk the up/down cable turnbuckle adjustment to optimize the clearance from the panel, firewall and bellcranks. At least this is what I have observed with the installations I have been involved with.

Larry

johneeb · Post by **johneeb** » Thu Dec 01, 2005 4:21 am

Before:

After:

I found every thing that George and Larry said to be true. A lot of Finesse goes on here to make this work out, but hay if I can do it, it can't be rocket science.

c170b53 · Post by **c170b53** » Thu Dec 01, 2005 5:12 am

I've said it before, I'd go with Harry's setup, if I could do it all over again. I did the Avion when Avion said that they were seeking an STC approval for the 170.
In my case I used 172 "M" shafts with the U control yoke and it worked like a charm. I also used 172 direct cables to avoid using splices in the aileron system. Elevator travel and control column throw is determined by the stops at the aft bulkhead, or in other words if your control column is hitting instruments, you gotta move the instruments.

simatos · Post by **simatos** » Fri Dec 02, 2005 3:19 am

You guys Thanks for this additional info. The Delair set up looks very much like my Avion set up. Avion also asked for the lower part of my stock "T" yoke and then welded a "U" shaped assembly which is tilted forward as opposed to the straight stock yoke. I didn't get to the hangar today but hope to on the weekend. The elevator travel angles have been checked by my AME, adjusted and landing ok on the stops in the tail. My actual control columns it seems to me would be in a better position if they were 3 inches or so shorter. I will look it all over on sat and get back to you Thanks again Gary