Control Cable Question (Cessna 150C)

[Mark Horak]

When I taxi my C150 I often hear what sounds like a control cable knocking against the fuselage. So I looked back in there today. The attached picture is not 3D and does not make this as clear as I would like, but as far as I can see there is only one cable in position to hit the fuselage and cause the sound I am hearing. It is the rudder cable noted in the photo with an arrow. The curious thing is that this seem to be by design.

Note that the other rudder cable is routed through an intentional guide hole, which I have circled. So one rudder cable goes through a guide hole, and the other rubs on the fuselage, by design. Can anyone venture an explanation for this design?

I'm not worried about the cable breaking because I don't use the rudder. :-) But I would like to understand this.

[Tom Charlton]

When I taxi my C150 I often hear what sounds like a control cable knocking against the fuselage. So I looked back in there today. The attached picture is not 3D and does not make this as clear as I would like, but as far as I can see there is only one cable in position to hit the fuselage and cause the sound I am hearing. It is the rudder cable noted in the photo with an arrow. The curious thing is that this seem to be by design.

Note that the other rudder cable is routed through an intentional guide hole, which I have circled. So one rudder cable goes through a guide hole, and the other rubs on the fuselage, by design. Can anyone venture an explanation for this design?

I'm not worried about the cable breaking because I don't use the rudder. :-) But I would like to understand this.

Hi Mark,
Don’t recall how the C-150 is rigged but with some aircraft, like my old Piper Cub, the rudder cable tension is maintained via springs and/or foot pressure on the pedals. If/when the springs get old/weak the rudder cables will . . . ah . . . sag.

Regards,
Tom Charlton

[kmccutcheon]

Tom hit the nail on the head. Springs attached to the rudder pedal torque tubes, pull the pedals forward and maintain a slight tension on the rudder cables. The springs aren't very big and I think I remember hearing this in new aircraft, back when I flew new C150s. Keep you feet on the pedals, or turn up the radio...

[Mark Horak]

Thanks, and sorry for the delayed response. I will just continue assuming this is normal slack, especially in a 55 year old airplane. I will also mention that looking closely at the simplicity and insubstantiality of the overall cabling mechanisms is rather provocative, considering that it could take, say, just a single broken cotter pin to end me. Life on the edge. :-)