Throttle cable interference

[Bruce Fenstermacher]

I received this question in a private email. I'm posting it here with my answer to see if others have this problem and what if anything was done about it.

Bill and I noticed a problem with an interference between the throttle cable and the vertical tube section of the control yoke on Bills '52 B model. When the yoke is pulled fully aft, the vertical tube touches the throttle cable housing. The problem seems to stem from the placement of the throttle control almost directly in line with the vertical tube. In Bill's plane, an attempt had been made to minimize the problem by using tie-wraps to pull the throttle cable hard to one side.
Is this a design issue with the C170, or is there some way to adjust things to prevent the yoke from brushing the throttle cable housing. Bending the throttle cable hard to one side just behind the instrument panel seems to put a lot of stress on the non-flexible part of the throttle control.

Thanks
Charles

Charles
I'm assuming the throttle is located in the original position as well as the exit through the firewall.

While I haven't looked at mine recently I seem to remember very much the same situation with mine. I seem to remember that I reached a compromise between running the cable as straight as possible and hitting the yoke. I fiddled around with the cable but the best I could do was to only have the cable hit the yoke at the extreme back position. This position is rarely if ever used in flight or on the ground so the cable rarely will actually hit the yoke. Again it was a compromise and not an ideal solution. I protected the cable with a plastic sheath as well.

[dacker]

I have the same situation with mine (notice that I didn't call it a problem). Though not ideal, Bruce has the same thinking that I do, it only touches when the yoke is in the extreme aft location. generall only used when flaring. I just replaced my throttle cable recently, the old one only had very minor scuffing from where it rubbed, and I believe it was the original with around 4000 hours. The aileron cables have never shown any signs of being worn. This is something that I put on my inspection list for annuals. The sheath sound like a good idea, but only if it is such that it won't create any edges to catch on.
David

[Jr.CubBuilder]

My 52B has the same issue. If I have it long enough the panel will be rebuilt, and the throttle cable will be moved over to the right to clear the yoke. I really don't like the way it is now, but it's been that way for half a century and as you guys noted in the above posts it only hits when you pull the yoke all the way back.

[n3833v]

I think I remember that the problem on mine and another that I saw had wedge washers to cant it to the side to clear. I"m not sure how mine is now that I have redone the panel.

John

[cessna170bdriver]

I've never noticed this problem on my '55, but it may be that the throttle is mounted slightly further to the right than earlier models. Mine also has the wedge washer, but that seems to be used to account for the slightly forward angle of the panel the throttle is mounted on.

Miles

[GAHorn]

"Angle" adaptors were used on aircraft subsequent to sn 25372 to divert the throttle cable away from the yoke. SN's 25373-26038 used it to divert the throttle to the right (handle actually points slightly toward the pilot), while later SN's diverted it slightly upward. Earlier aircraft (prior to 25373) seems to have used both a special washer in lieu of adaptor, and a bracket attached behind the glove box to reposition and hold the throttle cable away from the yoke. Fig 37, item 70 applies.

[KMac]

I have the same situation with mine as does at least one other based at my field. I had to cut a nylon bushing at an angle to act as a wedge washer. The aileron cable still touches the throttle cable when pulled full aft/up. I spoke to McFarlane (where my new throttle cable came from) and they make wedge washers to angle the cable through the panel. I bought some but my nylon one works better - I think. Hope that helps.
Kevin

[Metal Master]

" Earlier aircraft (prior to 25373) seems to have used both a special washer in lieu of adaptor, and a bracket attached behind the glove box to reposition and hold the throttle cable away from the yoke. Fig 37, item 70 applies.

I got curious about this issue because My 170 A SN# 19762 has the same issue. My throttle cable hits rubs on the control column vertical part when it is pulled back and forth. This was easy to view when the firewall was removed for replacement). I have not addressed it yet because I have not finished the right wing and so final assembly is still a few months away. Looking at the parts catalog for the 170 A Item #105 figure 35 part number 0413116-5 is no longer installed in my aircraft probably removed in the past. I am curious what the spacer part number 0413150 listed as a component part of the throttle item # 91 looks like. It is not shown on the drawing and is noted as being on the (back side of the instrument panel) and an AN960A816L washer listed as being installed on the (front side of the instrument panel). Of course an AN thin washer such as this is is not tapered. I will probably just make a tapered bushing for the installation when it comes down to it.

[GAHorn]

Just as a little note... The AN960A-816L desgination is an "untreated Aluminum" washer. It's not a thin, steel, cad-plated washer like an ordinary AN960-816L would be.
That's an old designation no longer found very easily. You might substitute a AN960D-816L washer for it as a close-substitute. (The "D" is an anti-corrosion chemical-treated aluminum washer.)