Flight Control Cables

Question 1

What are some of the advantages to using cable over mechanical linkage of push-pull rods?

Answer 1

Flexible without setting (permanent deformation), routed easily around obstacles by use of pulleys, installed over long distances without great degree of sagging, cable failure is never abrupt due to large number of wires used, lightweight, controlled systems respond quickly and accurately to cockpit movements with no loss of motion.

Question 2

What type of cable is commonly used in CG aviation? and what sizes does it come in?

Answer 2

Type 1 Mil Spec Mil-C 18375. 3x7, 7x7, 7x19, and 6x19

Question 3

What is a cable terminal?

Answer 3

Devices attached to the cable to make up a cable assembly, used to adjust and connect control cables to various components.

Question 4

What is the definition of swaging? List some commonly swaged terminal fittings.

Answer 4

A squeezing process by which the metal of the terminal is cold-flowed (shaped) onto the cable. Double-shank ball, single-shank ball, threaded, eye end, fork end terminals

Question 5

What is a turn buckle assembly?

Answer 5

A screw-adjusting device used to adjust cable tension, consists of a center barrel and two end terminals swaged to the cable.

Question 6

What do sectors and quadrants do?

Answer 6

Change the lateral motion of the cables to a rotation motion and gain mechanical advantage by means of leverage.

Question 7

What are pulleys designed to do?

Answer 7

Change cable direction while producing a minimum of friction and wear.

Question 8

If you set a cable in hot weather and then the aircraft transfers to a colder climate, what will happen?

Answer 8

Airframe will contract in the cold, causing loosening of the cable. (and vise versa)

Question 9

What are critical fatigue areas?

Answer 9

When a cable contacts a pulley, fairlead, or any other component or structure and within 12 inches of a swaged fitting.

Question 10

What is the preferred method when checking for broken wires?

Answer 10

Rag inspection

Question 11

How many broken wires is cause for cable replacement in critical areas? non critical areas?

Answer 11

Critical- 1, Non critical-3

Question 12

What two things should never be used to clean cables and why?

Answer 12

Metallic wool- will imbed dissimilar metal particles in the cable and cause corrosion. Solvents- will remove internal cable lubrication.

Question 13

What happens when internal corrosion is suspected?

Answer 13

Cable replacement is required.

Question 14

What percent of cable wear is acceptable and within limits?

Answer 14

30%

Question 15

What percent of cable wear should be written up in EAL and replaced at the next convenient time?

Answer 15

40-50

Question 16

At what percent wear will cables require immediate replacement?

Answer 16

50% and up

Question 17

What is one consideration that must be made when testing cable tension?

Answer 17

Airframe temperature, due to different rates of expansion.

Question 18

The SN on the cable tensiometer and cable tensiometer have to match prior to reading the chart. Why?

Answer 18

The chart is calibrated to the tensiometer and is accurate only for that tensiometer.

Question 19

Fairleads must not deflect the run of a cable how much?

Answer 19

More than 3 degrees from a straight line.