The Cessna 120-140 Association Forum

I am beginning to rig my 120 and have been following the manual but I can't figure out how to measure the required 40 +/- 10 lbs of tension for the carry thru cable. How is cable tension measured?

scotts97385 wrote: ↑Sat Mar 18, 2023 8:27 amHow is cable tension measured?

With a (ridiculously expensive) device called a tensiometer. Your A&P should have one, or access to one.

40+/- 10 lbs sounds high to me. Where did you find that? Operator's handbook says "about 30 pounds". If you make them to tight the controls will not operate smoothly and the system will wear excessively. The tension varies with temperature, too, so if you set them to 40# at 0*F you might bend something on a 100* day.

Mine are set about 25 on a standard day.

30 pounds tension is equivalent to fastening one end of the cable to the ceiling and hanging a 30 pound weight on the other end.

John is correct.
Page 36 of the Operations Manual for the Cessna 120/140 has the instructions.

Rick