Changes Due To Aligning Engine to Cowl?

[Jim Meade]

On 11/21/2022 at 10:33 AM, Tom Baker said:

There are consequences to shimming the lower part of the motor mount. When you move the lower mount out it loosens the rudder cables. By adding shims on the right side to move the spinner to the left you reduced the right rudder cable tension. This would make the airplane pull to the left, and require right rudder trim. if you didn't, you will need to adjust the steering rod to re-tension the rudder cables. Especially on the right side.

Just a word of caution. If you make big adjustments with shims you can loosen the cables enough that the rudder could be loose enough that flutter is possible on a test flight.

Where and how do you measure cable tension?

It occurs to me that one can check engine mount correctness including rubber washer by checking cable tension.  If the cable was initially correct and is now out of the tension spec and there were no changes to the tension adjustment mechanism, the engine must have moved, maybe due to rubber washer deterioration, and needs to be brought back into spec.

So, my question goes back to how and where do you measure rudder cable tension?

[Tom Baker]

First off, the engine rubbers will not effect cable tension. It is adjustment of the "T" frame that will cause the change. Besides cable stretch, only changing the shims or possible bending the "T" frame will cause a change. While not ideal there is a short stretch of bare rudder cable in the forward tunnel where you can check with a cable tensiometer. There are a couple quick things you can check. First feel the trailing edge of the rudder for movement. It is a quick check that will tell you if the cables are to loose. Second is when attaching the steering rods after maintenance where they were disconnected. When attaching the second rod you will have to stretch the cable by pushing on the rudder pedal while holding the nose wheel. To tight and you will have trouble getting the bolt through the rod end lined up. To loose and it will be to easy. With practice you will develop a feel for how much force it will take, but of course verify with the tensiometer. 

Roger says you can measure the cable tension at the trailing edge of the rudder, but I have never heard that method explained. 

[Jim Meade]

Thanks, Tom

[Roger Lee]

"Roger says you can measure the cable tension at the trailing edge of the rudder, but I have never heard that method explained. "

This is in the CTSW manual on how to measure the cable tension with the rudder. I've done it maybe 6 times. If the cables are too lose then the rudder gets easily moved in flight by crosswinds.

[FredG]

Not sure I understand how the rudder (of an airplane in flight) gets moved by "crosswinds".  

[Tom Baker]

3 hours ago, Roger Lee said:

"Roger says you can measure the cable tension at the trailing edge of the rudder, but I have never heard that method explained. "

This is in the CTSW manual on how to measure the cable tension with the rudder. I've done it maybe 6 times. If the cables are too lose then the rudder gets easily moved in flight by crosswinds.

Do you have a page or paragraph number, or manual version? I don't recall seeing it, and I looked through it again today.

[Anticept]

I swear I have seen that method somewhere too. Basically, you have to pull until it reaches a certain degree of deflection and read the value from the pull scale. But I can't find it in the maintenance manual either. Maybe it was a repair instruction.

[Jim Meade]

CTSW MM 4.3.3.5 refers to 4.3.3.4.3.  The discussion is about the rudder return system.  I mentions an effect of excessive tension, but I don't see it as a way to verify cable tension.