11.9 System Operation

Question 1

Manually operated systems include a combination of?

Answer 1

chains, control cables, turnbuckles, tension regulators, pulleys, fairleads, quadrants, torque arms, cable drums, jackscrews, bell cranks, and push-pull control tubes

Question 1

when was mechanical systems used?

Answer 1

on early aircraft and is still currently used in smaller aircraft where aerodynamic forces acting on the control surfaces are not excessive

Question 2

who controls these mechanical operated systems?

Answer 2

manually operated by the flight crew

Question 3

what is the usual configuration of cables used on aircraft and what material are they made out of?

Answer 3

7x7 and 7x19 flexible steel wires

Question 4

do flexible cables give a pushing force a pulling force or both?

Answer 4

a pulling force

Question 5

what system is implemented so you can pull both ways?

Answer 5

a closed loop providing a two way pulling action

Question 6

how can you identify cables on a bigger aircraft?

Answer 6

through a labelling/naming system so engineers can identify the function

Question 6

how can you change the direction of the cables?

Answer 6

pulleys

Question 7

what lubrication do pulleys need?

Answer 7

other than the lubrication at the factory none is needed

Question 8

how are cables kept in place when passing over pulleys?

Answer 8

they are kept in place by guards

Question 8

what support the pulleys?

Answer 8

brackets fastened to the aircraft

Question 9

what are fairleads used for?

Answer 9

fairleads are used to guide control cables along their length

Question 10

what are fairleads generally made from?

Answer 10

generally made from plastic, phenolic, resin or nylon

Question 11

what are fairleads primary functions?

Answer 11

their primary purpose is to dampen cable vibration, seal apertures in bulkheads and maintain cable alignment

Question 12

when a cable is going from a pressurised area to a non pressurised area what is needed?

Answer 12

seals are needed to prevent loss of cabin pressure

Question 13

what are tensiometers used for?

Answer 13

making sure the cable tension is correct

Question 14

what can improper cable tension cause?

Answer 14

can cause loss of control travel or damage to components

Question 15

when properly maintained how accurate is a tensiometer?

Answer 15

98%

Question 16

How is cable tension determined?

Answer 16

by measuring the amount of force needed to make an offset in the cable between two hardened steel blocks called anvils

Question 17

what is a riser used for?

Answer 17

to press against the cable to form the offset

Question 18

How do you operate a tensiometer

Answer 18

1)Raise the trigger and place the cable to be tested under the two anvils.
2)Close the trigger (move it down). The movement of the trigger pushes up the riser, which pushes the cable at right angles to the two clamping points under the anvils.
3)The force that is required to do this is indicated by the dial pointer.

Question 19

how do you read the tension on a tensiometer?

Answer 19

the dial on the front

Question 20

why is a tension regulator used?

Answer 20

Due to the expansion and contraction of the aircraft structure with changes in temperatures, some aircraft use cable tension regulators to maintain proper cable tension

Question 21

What is a cable tension regulator?

Answer 21

A cable tension regulator is a mechanical device that when fitted in a cable system, allows the cable under all conditions of temperature change and structural deflections to be taken in and let out equally on each side of the circuit, helping to maintain a uniform tension

Question 22

in what direction can push pull rods be used pull, push or both?

Answer 22

Both

Question 23

what are some disadvantage of using a push-pull rod system?

Answer 23

have a higher weight and cannot be routed easily through the aircraft structure without complicating the control system

Question 24

where are bell cranks often used?

Answer 24

in conjunction with control rods

Question 25

how are bell cranks constructed?

Answer 25

a series of levers can receive an input signal and deliver an output

Question 26

when is a torque tube used?

Answer 26

when an angular or twisting motion is needed

Question 27

what are screw jacks used for?

Answer 27

they are used for moving surfaces that experience extreme aerodynamic loads, such as horizontal stabilisers and trailing or leading edge flaps