Powered Flying Controls

Question 1

Powered flight controls are operated by

Answer 1

Hydraulic actuators or powered flying controlled units

Each actuator is operated by a servo controlled valve

Have 2 or 3 actuators per fling control

Question 2

Disconnect levers

Answer 2

Protects against jamming of controls

Reduces roll rate

Each pilot in control of their side

Question 3

Shear rivets

Answer 3

Protect against control jamming - shear at a designated load - allows the remaining aileron to be used

Rudder centring may be lost when this is used

Question 4

Power assisted control operation

Answer 4

Stick is connected to the valve and the hydraulic jack

When moved - hydraulic lock is unlocked in the power control unit/ hydraulic servo unit - moves the

High loads will get feedback - reversible - not artificial feel req

Question 5

Fully powered control operation

Answer 5

Stick only operates the servo valve actuator or if fly by wire - cables and levers

Irreversible- needs artificial feel

Control is lost if hydraulic pressure is locked

Question 6

Artificial feel systems are fitted

Answer 6

In parallel and duplicated

Senses dynamic pressure and control deflection - reduces the chances of over stressing the a/c

Question 7

Artificial feel Q feel operation

Answer 7

Q pot - senses dynamic pressure by having a feed from pitot and static pressure

Diaphragm moves up and down depending on airspeed - as it moves upwards (more IAS) - allows more hydraulic pressure to go into the piston = harder to move the control column

Question 8

The a/c may need to be trimmed in flight as a result of

Answer 8

Changes of speed and power

Varying CG posn

Trimming reduced the control loads to zero - either a control wheel or a selection of switches

Question 9

Methods of trimming

Answer 9

The trim tab - moves in the opposite direction of the control surface

Variable incidence tailplane

CG adjustment - moving fuel around

Adjustment of the artificial feel unit - feel trim unit - combination of artificial and trim unit

Question 10

Disadv of a trim tab

Answer 10

Reduces control authority in the direction of the trimming

Also increases drag

Question 11

Fixed tabs

Answer 11

Not adjustable in flight

A/c has a permanent out of trim posn

Adjusted on the ground

Question 12

Horizontal stabiliser trim is operated by

Answer 12

Older a/c - hydraulically

New a/c = electric

Both move a screw jack

Question 13

If the variable incidence tailplane is not in the t/o posn for t/o

Answer 13

Intermittent horn will sound in the f/d

Question 14

Variable incidence tailplane can be operated by

Answer 14

Trim wheel
Or
Switches that operate in pairs - one controls the power and another does the direction - prevents trim r/y - must be moved together

Question 15

Adv of variable incidence tailplane

Answer 15

Drag is less

Trimming does not reduce the control authority

Question 16

Mach trim purpose and operation

Answer 16

C or p moves rearwards at high airspeed - large nose down pitch moment - this prevents it

System will kick in at a datum speed - will move trim/fuel to prevent tuck under

Question 17

2 systems and diff in operation to prevent excessive rudder deflection at high airspeeds

Answer 17

Rudder ratio changer - Boeing - rudder pedals move through their full range - rudder deflection reduces with increasing IAS - not proportional

Variable stop systems - airbus - movement of the rudder is proportional to rudder travel - range of movement is reduced for both of them - starts to reduce at around 165kts

Question 18

Fly by wire

Answer 18

Mechanical input converted into an electrical output

Question 19

Adv of fly by wire

Answer 19

Relax the natural stability of the a/c - reduce the size of the tailplane - do not need to de ice as much - increases fuel efficiency - reduces weight

Reduces flight crew workloads

Question 20

Flight envelope protection takes into account

Answer 20

Pitch attitude protection
Load factor protection
Bank angle protection
AoA protection

Question 21

Control locks

Answer 21

A/c with reversible commands - when parked wind can damage the control surfaces - control locks manage this