11.9 System Operation Flashcards
Manually operated systems include a combination of?
chains, control cables, turnbuckles, tension regulators, pulleys, fairleads, quadrants, torque arms, cable drums, jackscrews, bell cranks, and push-pull control tubes
when was mechanical systems used?
on early aircraft and is still currently used in smaller aircraft where aerodynamic forces acting on the control surfaces are not excessive
who controls these mechanical operated systems?
manually operated by the flight crew
what is the usual configuration of cables used on aircraft and what material are they made out of?
7x7 and 7x19 flexible steel wires
do flexible cables give a pushing force a pulling force or both?
a pulling force
what system is implemented so you can pull both ways?
a closed loop providing a two way pulling action
how can you identify cables on a bigger aircraft?
through a labelling/naming system so engineers can identify the function
how can you change the direction of the cables?
pulleys
what lubrication do pulleys need?
other than the lubrication at the factory none is needed
how are cables kept in place when passing over pulleys?
they are kept in place by guards
what support the pulleys?
brackets fastened to the aircraft
what are fairleads used for?
fairleads are used to guide control cables along their length
what are fairleads generally made from?
generally made from plastic, phenolic, resin or nylon
what are fairleads primary functions?
their primary purpose is to dampen cable vibration, seal apertures in bulkheads and maintain cable alignment
when a cable is going from a pressurised area to a non pressurised area what is needed?
seals are needed to prevent loss of cabin pressure
what are tensiometers used for?
making sure the cable tension is correct
what can improper cable tension cause?
can cause loss of control travel or damage to components
when properly maintained how accurate is a tensiometer?
98%
How is cable tension determined?
by measuring the amount of force needed to make an offset in the cable between two hardened steel blocks called anvils
what is a riser used for?
to press against the cable to form the offset
How do you operate a tensiometer
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.
how do you read the tension on a tensiometer?
the dial on the front
why is a tension regulator used?
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
What is a cable tension regulator?
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
in what direction can push pull rods be used pull, push or both?
Both
what are some disadvantage of using a push-pull rod system?
have a higher weight and cannot be routed easily through the aircraft structure without complicating the control system
where are bell cranks often used?
in conjunction with control rods
how are bell cranks constructed?
a series of levers can receive an input signal and deliver an output
when is a torque tube used?
when an angular or twisting motion is needed
what are screw jacks used for?
they are used for moving surfaces that experience extreme aerodynamic loads, such as horizontal stabilisers and trailing or leading edge flaps
