B757 Flight Control Systems

Front 1

What 2 categories are the flight controls broken into?

Back 1

Primary and Secondary

Front 2

What is required for movement of the flight controls?

Back 2

Hydraulic power.

Front 3

What are the flight control shutoff valves?

Back 3

3 electrically controlled valves used to isolate the aft flight controls for ground testing.

Front 4

What are PCA's?

Back 4

25 linear piston type output hydraulic power control actuators

Front 5

How is longitudinal movement of the A/C controlled?

Back 5

By a pair of conventional ailerons assisted by the roll control function of the spoilers.

Front 6

How many cable sets does the ailerons have?

Back 6

4

Front 7

How is aileron feel achieved?

Back 7

Cams and springs

Front 8

How is aileron trim achived

Back 8

By moving the central position of the cam

Front 9

How many override mechanism does the aileron system have?

Back 9

4

Front 10

How are contrasting control inputs managed?

Back 10

Spring loaded bus bar between the pilots

Front 11

Which spoilers are only used on the ground?

Back 11

4 and 9

Front 12

What conditions must be met for auto speed brake operation?

Back 12

Must be armed, both MLG must be down, both MLG truck tilt pressure switches must read high pressure, both thrust levers must be below 50% of total travel.

Front 13

What are the 6 sub systems of the CSEU?

Back 13

Elevator asymmetry limitor actuators, rudder ratio actuators, stab trim control modules, yaw damper actuators, spoiler actuators L&R

Front 14

Under what condition will the speed brakes always be in the up position?

Back 14

When the thrust reverses are placed in reverse.

Front 15

What position will the spoilers go to given no system input?

Back 15

Down

Front 16

What do the RVDTs provide from the spoiler PCAs?

Back 16

Feed back signals by measuring the change in actuator angle.

Front 17

What controls the spolier PCAs and through what?

Back 17

Spoiler control modules through the Electro Hydraulic servo valves.

Front 18

What inputs control yaw damper summing assembly?

Back 18

Control path, temp compensating rod, yaw damper

Front 19

What is significant about the rudder pedals?

Back 19

Independently adjustable, single cable system.

Front 20

Where are the rudder trim actuators located?

Back 20

Feel centering and trim mechanism.

Front 21

What are the rudder auto pilot servos know as?

Back 21

Rollout guidance servos

Front 22

How does the aileron and rudder trims adjust the trim mechanisms

Back 22

By adjusting the the neutral position of the feel centring mechanism cam and rollers

Front 23

Why would a spring cartridge/ pogo rod be used in the rudder control system?

Back 23

To compensate for slight rigging irregularities.

Front 24

What is the purpose of the rudder ratio changer?

Back 24

Limits the amount of rudder travel as a function of airspeed.

Front 25

What degrees of movement does the rudder ration changer limit the rudder to at high speed and lower speed?

Back 25

High speed 3.5°, low speed 30°.

Front 26

How does the rudder ratio changer control the amount of movement?

Back 26

Through signals received from the ratio changer modules with information provided from the ADC which moves the electronically control hydraulic actuator.

Front 27

Which 2rudder PCAs will be solely in control should left system pressure fail or should the ratio changer fail?

Back 27

Lower (right sys), Upper (centre sys)

Front 28

What is the purpose of the yaw damper?

Back 28

To keep the aircraft stable about the vertical axis and to ensure co-ordinate handling.

Front 29

How much can the electro hydraulic servos deflect the rudder?

Back 29

3° left and right of centre

Front 30

What displays rudder position?

Back 30

Transmitter located on the lower PCA sends signals to EICAS

Front 31

What is significat about the elevator control surfaces?

Back 31

They are independent and not mechanical to allow limited asymmetric operation

Front 32

At what force do the elevator control columns overide to allow independent movement?

Back 32

65lbs

Front 33

What do the elevator cable systems incorporate?

Back 33

Tension regulators

Front 34

What makes up the aft quadrant assembly?

Back 34

Dual feed centring mechanism, mechanical link with override, asymmetry limiter, neutral shift device, and autopilot pitch controls

Front 35

How is elevator feel achieved?

Back 35

Through the use of a Feel computer and Feel actuator.

Front 36

What inluts a feel computer?

Back 36

Pitot static and centring cam

Front 37

How does a feel unit achieve elevator feel?

Back 37

Hyd input from the right and centre systems is controlled pitot pressure through bellows transmitted to a dual tandem hyd actuator connected to a centring cam out to the elevator quadrants

Front 38

What is neutral shift?

Back 38

Is the automatic centring of the elevator control system to achieve trim through a direct link to the Hori stab position of 0-4 nose up. This keeps the 2 surfaces in tune in high nose up settings.

Front 39

What are SAM'S?

Back 39

Elevator asymmetry Modules.

Front 40

Describe the elevator asymmetry limiter.

Back 40

A electronically controlled actuator that limits the movement between the elevator aft control quadrants for 24° at low speed to 8° at high speed through information provided by the SAM module and position sensors.

Front 41

Where does the Asymmetry limiter receive speed information from?

Back 41

The air data computers through the SAM modules

Front 42

What pressures do the elevator PCAs run at normally?

Back 42

2250psi.

Front 43

What condition must be met for the eleveator PCAs to run at full pressure?

Back 43

Right system failure.

Front 44

What 4 ways can the hori stab pitch trim system be operated?

Back 44

Pilots switches, alternate switch (left of thrust reverser), autopilot, by MACH/Speed trim system

Front 45

What is the difference between MACH trim and Speed trim?

Back 45

Speed trim is determined by having flaps down while MACH is with flups up.

Front 46

How can the pilot override trim settings for the alternate switch?

Back 46

By simply operating the column controls, triggering cam switches deactivating trim inputs from all sources?

Front 47

What gives stabilizer trim airspeed information?

Back 47

Elevator feel computer.

Front 48

What signal dictates the rate control valve in the Stabilizer trim control module?

Back 48

Airspeed via hyd signals from the elevator feel computer.

Front 49

What would happen if only one hyb motor pump were working on the stabilizer trim actuator?

Back 49

Power output would be halved.

Front 50

What 3 components make up the stabilizer position indicating system?

Back 50

3 stabilizer trim limit switches and position transmitter modules, travel limit switches

Front 51

What does the stabilizer position indicating system do?

Back 51

Limits stabilizer movement.

Front 52

What feedback signals does the stabilizer position indicating system give to?

Back 52

Autopilot, SAM's, position indicators