11.9 Flight Controls Flashcards
What are the primary flight controls?
Ailerons
Elevators
Rudder
What do ailerons give?
Longitudinal control
What control do elevators give?
Lateral
Unlike the other what is the direction of movement of an anti balance/servo trim?
Same direction of movement.
Where is lateral trim controlled from?
Switch on the centre console, electrically controlled through the FCU.
What are SPMs?
Stabiliser position modules.
What two active aeroelastic control techniques are there?
Manoeuvre Load Control
Gust Load Alleviation
What can active load alleviation systems be based on?
Feedback loop (wing tip acceleration) or feed-forward channel (angle of attack)
What is the aim of Manoeuvre Load Control?
To use wing control surfaces to move the lift inboard during manoeuvres so that wing bending is reduced.
What is the aim of Gust load allieviation?
Fly by wire aircraft that reduces the effect of gust loads by deflecting control surfaces.
What is the typical flap extension for takeoff?
5 to 15 degrees
What is the typical flap extension for landing?
25 to 40 degrees
What are the lift dump spoilers?
Flight roll spoilers
What cables are commonly used in aviation?
7x7 and 7x19
In the UK how are control cables classed?
Minimum breaking load in hundred weight force (cwtf)
What are cables often made from?
Linear reinforced phenolic resin or aluminium alloy.
When do pulley bearings need lubing?
They don’t after manufacture.
How accurate is a tensiometer?
98%
Where are bell cranks used?
In conjunction with control rods
What do bell cranks allow?
A change of direction.
When are torque tubes used?
When an angular or twisting motion is needed.
What type of thread do screw jacks have?
Coarse
In damping mode what happens to the servo unit in a hydraulic pump?
Depressurised.
What is a servo control unit divided into?
Power
Distribution
What are the main components in a servos power unit?
Cylinder
Piston
Rod
What are the main components in a servos distribution section?
Control valve
Bypass valve
What two main operating modes does a servo control unit have?
Control/active
Damping
In a power assisted flight control system does the pilot have feedback?
Yes
In a full power flight control system does the pilot have feedback?
No
What are pneumatic control systems used for?
Backup on systems such as landing gear and emergency brake.
When three channels on fly by wire are being used what is it known as?
Triplex
What is normal law in a fly by wire system?
Pre-set characters for the aircraft depending on the stage of flight.
What are the three flight control modes in fbw?
Ground
Flight
Flare
What happens in fbw ground mode?
Auto-trim is turned off and there is direct input into the flight controls. Horizontal stab is 4 degrees up.
How long is the transition time between ground to flight mode?
5 seconds
What 5 protections does flight mode offer?
Pitch attitude
Load factor limits
High speed
High AOA
Bank angle
When does flight mode cut out on landing?
100 feet
What is ALT1 mode?
Combines normal law lateral mode with the load factor.
When may ALT1 be entered?
If there are faults in the horizontal stabiliser, an elevator, yaw-damper actuation, slat or flap sensor, or a single air data reference fault.
What is ALT2 mode?
Protection for high angle of attack and speed.
When is ALT2 entered?
When two engines flame out faults in two inertial or air-data references, with the autopilot being lost.. This mode may also be entered with an all-spoilers fault, certain aileron’s fault, or pedal transducer’s fault.
What happens in direct law?
All protections are lost and all flying controls are manual input.
When is direct law entered?
Failure of three inertial reference units or the primary flight computers, faults in two elevators, or flame-out in two engine.
What is a feel unit?
Gives the pilot an artificial feeling of the aerodynamic loading.
What is a q pot feel system?
A very large simple piston feel unit.
When does mach tuck happen?
When aircraft transition through the transonic region.
How is mach tuck avoided?
Mach trim, keeps the nose up.
What is a gust lock?
Method of locking out flight controls.
What is static balancing?
The tendency of an object to stay still when balanced.
What are the two ways in which something is statically balanced?
Underbalance (+)
Overbalance (-)
What indicates overbalance?
Upward movement of the trailing edge.
What is dynamic balance?
All the rotating forces are balanced within themselves.
How is the neutral position determined before balancing?
Using a bubble protractor.
What is the advantage of the calculation method for balancing?
The surface doesn’t need removing from the aircraft.
What is aircraft rigging?
The adjustment and travel of the moveable flight control surfaces.
What is surface throw?
The correct prescribed arc of a flying control.
What is a stick nudger?
Designed to avoid stall.
What angle of attack gives maximum lift?
14 degrees
What is an alpha lock?
Prevents the slats from being retracted at high angles of attack, as when they get retracted the angle of attack is increased leading to flow separation.
