This document discusses the components and systems used in conventional aircraft flight controls. It describes cables, pulleys, turnbuckles, bellcranks, push-pull rods, quadrants, torque tubes, and cable guards that are used to transmit control forces through a cable-and-pulley system. It also discusses modern powered flight control systems that use hydraulics to provide some or all of the control forces, including power-assisted and fully powered controls. Fully powered controls provide all necessary control surface movement through hydraulics without input forces from the pilot. These systems require artificial feel devices to provide feedback to the pilot.

1. TECHNICAL GENERAL CPL
MRS.SOUMYA KUMARI K P/SGI/OFAA

2. CONVENTIONAL SYSTEMS
Components are
• Cables
• Pulleys
• Turnbuckles
• push-pull rods
• Bellcranks
• Quadrants
• torque tubes
• cable guards
• fairleads
MRS.SOUMYA KUMARI K P/SGI/OFAA

3. CABLES
• Aircraft-control cables are generally fabricated from carbon steel
or corrosion-resistant steel wire and may consist of either a
flexible or nonflexible type of construction.
• The flexible construction is generally used for aircraft controls.
•
MRS.SOUMYA KUMARI K P/SGI/OFAA

4. PULLEYS
• Pulleys are used in aircraft-control systems to change the
direction of a cable.
MRS.SOUMYA KUMARI K P/SGI/OFAA

5. TURNBUCKLES
• Turnbuckles are commonly used for adjusting the tension of the
control cables
MRS.SOUMYA KUMARI K P/SGI/OFAA

6. BELLCRANK
• A bellcrank is used to
transmit force and permit
a change in the direction
of the force.
MRS.SOUMYA KUMARI K P/SGI/OFAA

7. PUSH-PULL RODS
• The push-pull rod is used
between bellcranks and from
bellcranks to torque arms
(“horns”) to transmit the force
and motion from one to the
other.
• A pushpull rod connected to
a bellcrank is shown in Fig.
• Push-pull rods are also called
control rods because they are
often used in control systems
MRS.SOUMYA KUMARI K P/SGI/OFAA

8. QUADRANT
• A quadrant serves the same
purpose as a wheel; however,
the quadrant moves through
a relatively small arc, perhaps
as much as 100°.
• often employed at the base of
a control column or control
stick to impart force and
motion to a cable system.
MRS.SOUMYA KUMARI K P/SGI/OFAA

9. TORQUE TUBE
• A torque tube is a hollow
shaft by which the linear
motion of a cable or push-
pull tube is changed to rotary
motion.
• A torque arm, or horn, is
attached to the tube by
welding or bolting and
imparts a twisting motion to
the tube as the arm is moved
back and forth
MRS.SOUMYA KUMARI K P/SGI/OFAA

10. CABLE GUARDS, OR GUARD PINS
• Cable guards, or guard pins, are
installed in the flanges of pulley
brackets to prevent the cable
from jumping out of the pulley,
• The guard must be located so it
does not interfere with the
rotation of the pulley.
• A guard pin can be either a bolt,
a cotter pin, or a clevis pin.
MRS.SOUMYA KUMARI K P/SGI/OFAA

11. FAIRLEAD
• A fairlead serves as a guide to
prevent wear and vibration of
a cable.
• These units must be installed
in such a manner that there is
no contact between the cable
and the aircraft structure.
• The principal functions of
fairleads are to dampen
vibration, maintain cable
alignment, and to seal
MRS.SOUMYA KUMARI K P/SGI/OFAA

12. MODERN FLYING CONTROLS
Powered flying
controls
Power assisted
controls
Power
actuated
systems
MRS.SOUMYA KUMARI K P/SGI/OFAA

13. POWER ASSISTED
CONTROLS
• Only a certain portion of force
required to oppose the hinge
moment is provided by the
pilot, the hydraulic system
provides most of the force
• Although the pilot does not
have to provide all the force
required, the natural ‘feel’ of
the controls is retained
• The stick force increases as the
square of velocity
MRS.SOUMYA KUMARI K P/SGI/OFAA

14. FULLY POWERED
CONTROLS
• In faster/Bigger aircrafts hinge
moments are very high that a
fully powered controls must be
used
• None of the force required to
deflect the control surface is
provided by the pilot
• Only the system friction to
move servo valve is overcome
by the pilot input
MRS.SOUMYA KUMARI K P/SGI/OFAA

15. All the necessary power to move the
control surface is supplied by the
aircraft hydraulic system
Aerodynamic loads on the control
surface is unable to move the cockpit
controls, so powered flying controls
are known as “irreversible” controls
MRS.SOUMYA KUMARI K P/SGI/OFAA

16. ARTIFICIAL
‘Q’ FEEL
• With a fully
powered flying
control, the pilot
is unaware of the
aerodynamic
force on the
controls, so it is
necessary to
incorporate
“Artificial feel” to
prevent aircraft
from being
MRS.SOUMYA KUMARI K P/SGI/OFAA

17. ARTIFICIAL
‘Q’ FEEL
A device, sensitive to dynamic pressure or
Q is used
Pitot pressure is fed to one side of a
chamber and static pressure to the other
It moves the diaphragm under the influence
of changing dynamic pressure
It provides a “resistance” or “feel” on the
pilot input controls, proportional to speed
MRS.SOUMYA KUMARI K P/SGI/OFAA

18. THANK YOU
MRS.SOUMYA KUMARI K P/SGI/OFAA