6.10 control cables Flashcards
Where are cables used?
Smaller aircraft’s to transmit force to flight controls
What the advantages of cables?
ightweight
Flexible
Strong
High mechanical efficiency
What can cables transmit power without gaining?
Backlash
Why must tension be adjusted frequently?
Because the cables stretch over a period of timed
What disadvantage are cables prone to?
Prone to wear
What can cause tension to vary?
Temperature change
When cables stretch, do they become deformed?
No
Does vibration effect control cables?
no
Why are failures of in control cables rare?
Because of the amount of wires in a cable
All aircraft control cables are what in terms of manufacturing?
Preformed
What is the basic element of the control cable?
A strand
What is a strand?
A number of wires braided together
What do strands bundled together form?
A cable
When does wires and strands’ tendency to uncoil reduce?
When the wires and strands are twisted in the opposite direction, but the cables are wrapped in the same direction
What is the opposite direction twist also called?
A regular lay
If the strands are twisted around a central core, what is it called?
Lang lay
How are cables designated?
To the number of strands
What do aircraft cables diameter vary to?
1.6mm and 9.53mm
What does 1X7 mean?
One strand compromised of 7 different wires
What is involved in non flexible wires?
1 X 7
1 X 19
Where are non flexible wires used?
Straight runs where the cables don’t pass over pulleys
What is involved in flexible wires?
7 X 7
Where are flexible cables used?
Straight runs and where large pulleys are being used
What does extra flexible cables involve?
7 x 19
Where are extra flexible cables used?
Trim and flight controls (Areas that require a change in direction)
Terminal fitting are usually of what type?
The swage type
What are threaded end, fork end and eye ends used for?
To connect to turnbuckles and other linkage
What are ball terminals used for?
Attaching cables to quadrants, and other connections where space is limited
Where are single shank ball ends located?
On the end of a a cable
Where are double shank ball ends used?
Either on the ends of a cable, or in the centre
Where are thimble and bushing fitting used?
Terminal fittings where supplies are limited but the repair is needed
How can you help a cable compensate for temperature change?
By fitting cable tension regulators
What do cable tension regulators do?
Extension or compression of springs to adjust to cable quadrant positionings
What is dangerous about disconnecting cables?
They can spring back becsuse of the tension
What must aircraft cable regulators be in accordance with?
The AMM
Where are turnbuckles used?
Where tension is required
What must you do to a turnbuckle when you’re done with it?
It must be safetied or locked
What else is used to secure turnbuckles?
Single or double wrap method which used lock wire
What is a turnbuckle assembly?
A mechanical screw device consisting of two threaded terminals and a threaded barrel
What are turnbuckles used for?
To make minor adjustments and adjust cable tension
What is important when screwing a turnbuckle?
How many threads can be exposed?
Turn both turnbuckles an equal amount of turned into the barrel until no more than 3 threads are exposed
How can the end of the barrel with left hand threads be identified?
By a groove or knurl around the end of the barrel
How are lock clad cables produced?
By swaging aluminium onto galvanised or stainless aircraft cable
What is the code for lock clad cables?
7 X 7
7 X 19
Why was lock clad developed?
To eliminate sagging and wear in long aircraft cables
Why is lock clad used?
Stress is reduced
Sag is eliminated
Vibration is reduced
Aluminium tubing stops abrasion of outer wires
What are pulleys used for?
To guide cables and change the direction of cable movement
What is the state of pulley bearings before use?
Pre lubricated and sealed
What is used to support the pulley?
A bracket
How are cables passing over the pulleys kept in place?
By a guard
What is the guard pin?
A Clevis pin held in place by a split pin and washer to prevent damage
What are guards used for?
To prevent slipping or jamming
When is a fair lead or grommet used?
When there is possibility or the aircraft contacting the structure
What are push rods used for?
As links in the flight control system to give push pull motion
Where can push rods be adjusted from?
Both ends or one end
What does a push rod consist of?
A tube with threaded rod ends
What permits attachment of the tube to flight control system parts?
The rod end or clevis
What prevents the rod end or coves from unloosening?
A check it
How can control rods on bearings be prevented from loosening?
The flange of the rod end is interposed between the ball race and the anchored end
What are bell cranks and quadrants be made out of?
Heat treated aluminium
Where are ball cranks and quadrants used?
In push pull tubing systems to change direction of travel and mechanical advantage
What can cause a delay in response?
Wear where connection is
Why are torque tubes installed?
When an angular or twisting motion is required
What are aircraft cables only capable of in terms of forces?
Pulling
When a two directional force is needed, the use of what is needed?
When a two directional force is needed, the use of what is needed?
What does cable control consist of?
A single cable passing through a covering (conduit)
Why is straightening of a conduit prevented even though a pull force will try to bend it back into place?
Because the end fittings are fixed
What is a Bowden cable?
An inner steel cable which moves linearly and is free to slide
What do small aircraft use the Bowden cables for?
Throttle or fuel mixture control
When do Bowden cables fail to function smoothly?
When water or contaminants enter
What are teleflex controls used for?
To operate components
How do teleflex transmit force?
Through a push and pull motion
If the teleflex is not long enough, what can be used for connection?
Rigid cables or linkages
What else may be used as a thread?
A helix winding
Are cables interchangeable with each other on aircraft?
No
What way does DS 23/2 (No.2) turn?
Left no helix
What is DS 23/2 made out of?
steel
What way does DS 380 turn?
Right
What does DS 380 not have?
Compression wire
What is different about the diameter in DS 380?
Greater diameter than the core
Where is DS 169330 used?
Hot areas (it’s made of stainless steel)
What is the transmitting end of a control usually fitted with?
A wheel consisting of a hand operating gear
When can a push pull operating handle be used?
Where the loading is light and straight
What are swivel joints used for?
To take up angular movements
In a single entry unit, what is the rotary travel limited to?
270 degrees
When is a double entry used?
When greater travel is required
In double entry, what is the cable degree?
90 degrees 120 degrees 180 degrees
What is the short cable that comes out from the back of the conduit known as?
A spent travel tube
What is a straight lead unit?
The cable passes straight through the unit and engages on a few teeth on the wheel
What are straight lead units not suitable for?
Heavy loads
What are junction box units used for?
To reverse direction or to branch a run of cables
What does anti torsion tubes do?
Not allow the cable to turn in the conduit so doesn’t change the relative adjustments
Where can swivel joints be installed?
Where rotary movement of the control does not exceed 90 degrees
What do swivel joints consist of?
A ball and a socket
When are sliding end fittings used?
When it’s not necessary to convert the push pull motion into rotary
What do slide fittings comprise of?
Guide tube and end fittings
What are quick break units?
Facilitate removal of components without disturbing the control
What do conduit connectors have?
Nipples
What are conduit connectors similar in construction to?
All metal pipe couplings
What is a torsion drive?
The final linear movement of the control is converted to a rotary action using the distributor box
What is the torsion drive similar to?
The normal flexible drive
What is the distributor box similar to?
A receiver unit
In a distributor box, how can you convert the rotary motion of the torsion drive to the linear movement of a trmiming tab?
A sprocket driven screw jack
How is the left hand thread on a turnbuckle identified?
By a groove at the end of a barrel
Which type of cable is used in aircraft control and trim systems?
Extra flexible wires
