Primary flight controls

Question 1

What are the primary flight controlls

Answer 1

Pitch - Elevators
Roll - Aileron (plus roll spoilers)
Yaw - Rudder

Question 2

Means of actuation: (3)

Answer 2

Manual: cables, pulleys, bell cranks

Partially powered: Cables and leavers with actuator assistance

Fully powered: No mechanical connection between pilot’s control and control surfaces

Question 3

Describe reversable controls

Answer 3

Feedback from the control surface to the pilot controls

Question 4

If forces on the aerofoil are felt in the flight controls, it is what kind of control?
Manual / partially powered / fully powered

Answer 4

Manual - it’s connected by cables.
(reversable)

Question 5

What is this describing and is it reversable?

Hydraulic actuator attached in parallel to mechanical linkages. Movements of the pilot’s controls simultaneously move the control surface and a servo, which moves the actuator.

Answer 5

Partially powered system
reversable

Question 6

What is this describing and is it reversable?

The pilot’s controls use mechanical or electrical methods to operate a servo value controlling an actuator which moves the control surface.

Answer 6

Fully powered
non-reversable

Question 7

‘Feel’ or feedback is useful because

Answer 7

Means the pilot is unlikely to overstress the aircraft. Without, it would be easy to go full deflection on the controls at high speed.

Question 8

Fly-by-wire modes?

Answer 8

Normal
Degraded
Direct law

Question 9

Describe Fly-by-wire degraded
aka Airbus Alternative law

Answer 9

Some protections and finessing absent

Question 10

Describe Fly-by-wise Direct law

Answer 10

All computer mediation absent

Question 11

FBW disadvantages are?

Answer 11

Sensor failure renders the system useless

Question 12

Sidestick controller issues (AF447)

Answer 12

One pilot can’t see or feel the other

Question 13

THS stands for?

Answer 13

Trimmable Horizontal Stabiliser

Question 14

FBW system components are:

Answer 14

Actuators - to move controls

Computers - to interpret commands

Control surface position sensors - to provide feedback to computers

Triplicated or quadruplicated control wires running through different parts of the airframe

Question 15

Trimming functions are available on primary controls, what do they do?

Answer 15

Null the loads felt by the pilot.

Question 16

What does a trim tab do?

Answer 16

Creates a balancing load at the control surface

Question 17

THS, trimmable horizontal stabiliser is very powerful, give an example of this going wrong

Answer 17

Runaway stab
or
MAXs

Question 18

What do control locks do?

Answer 18

Protect reversable controls from banging against stops in gusty conditions.

Question 19

Check for what being removed before flight (to do with controls)?

Answer 19

Control locks

Question 20

Rudder limiter / ratio changer does what and why?

Answer 20

Limits the rudder travel at high speeds.
Leaves full deflection at low speed for asymmetric thrust in climb conditions

Question 21

The difference between Boeing and Airbus FBW systems is:

Answer 21

Hard law - Airbus
Soft law - Boeing

Question 22

In Boeing - what does ACE stand for and mean

Answer 22

Actuators comprise of 4 Actuator Control Electronic (ACE) units
The ACE is a Electro-hydraulic self-contained unit that has a dedicated hydraulic pump and oil supply and fitted directly to the control surface.