5.9 FLIGHT CONTROL

Question 1

What does the normal light mean on tail & wing switches (flight control surfaces)?

Answer 1

The respective flight control surfaces are unlocked.

Question 2

What does the lock amber lights mean on tail & wing switches (flight control surfaces)?

Answer 2

The flight control surface are locked, automatically unlocks when ground speed
exceeds 40 kts

Question 3

When will flight control surfaces FAIL light illuminate?

Answer 3

When a lock switch is in the lock position and any of the associated Surfaces are not
locked.

Question 4

How many flight control mode dose the aircraft have?

Answer 4

Normal , Secondary & Direct.

Question 5

How many flight control computers do B787 have?

Answer 5

3 PFC’s

Question 6

How many actuators control electronics?

Answer 6

4 ACE’s

Question 7

The PFC’s use informations from other airplane system what are they?

Answer 7

o IRU(lnertial reference unit )
o Slats & Flaps position
o ADR (air data reference)
o Radio altitude
o Engine thrust.

Question 8

What will cause the primary flight control to switch to secondary Mode?

Answer 8

When inertial or air data is insufficient to support normal mode or when all slat and flap
position data is unavailable.

Question 9

In the event of loss of all hydraulic power, what flight controls are available?

Answer 9

The electrically actuated stabilizer and 2 spoiler pairs, through the trim switches and
control wheel.

Question 10

If there is a complete loss of flight control signaling, what flight controls are available?

Answer 10

Direct wiring to the stabilizer and 1 spoiler pair, through the alternate pitch trim and
control wheel.

Question 11

What is the Envelope protection?

Answer 11

Stall protection, Overspeed protection, Bank angle protection

Question 12

What are the 3 flaps modes?

Answer 12

Primary, Secondary, Alternate

Question 13

When do the flaps and slats operate in secondary mode?

Answer 13

o When the Center hydraulic system has failed OR
o Control surface travel at less than 50% of the normal hydraulic rate OR
o Flaps or slats disagree is detected OR
o Flaps or slats primary control failure OR
o Primary mode fails to move the flaps and slats to the selected position OR
o Uncommand flaps or slats motion is detected.

Question 14

What is the difference between flaps and slats Primary, Secondary and Alternate
operations?

Answer 14

o Primary: Hydraulic
o Secondary : Electric or Hydraulic
o Alternate: Electric
Electric Operation is considerably slower

Question 15

When is primary pitch trim inhibited?

Answer 15

When autopilot engaged.

Question 16

Which has priority, Primary or Alternate pitch trim?

Answer 16

Alternate pitch trim.

Question 17

On ground, Moving the pitch trim moves which control surface?

Answer 17

Stabilizer.

Question 18

In normal mode, moving the pitch trim does what in flight?

Answer 18

It makes inputs to the PFCs to change the trim reference speed.

Question 19

What are the power sources for the horizontal stabilizer?

Answer 19

L2 & R2 AC buses.

Question 20

During flight, moving the pitch trim while in Secondary or Direct mode moves what
control surface?

Answer 20

The Stabilizer.

Question 21

In which mode is Flight Envelope Protection available?

Answer 21

Normal Mode.

Question 22

Can the crew select secondary mode manually?

Answer 22

No.

Question 23

In Secondary mode, what type of command do the 3 PFCs compute flight control surface
commands? Are the ACE’s fully functional?

Answer 23

The PFC’s use simplified commands and the ACE’s are fully functional

Question 24

What functions are not available in the Secondary and Direct modes?

Answer 24

o Autopilot.
o Auto speedbrakes.
o Flight Envelope Protection.
o Tail strike protection.
o Gust suppression.
o Pitch Compensation.
o Roll/Yaw asymmetry compensation.

Question 25

When will the Flight Control System revert to Direct mode?

Answer 25

When all 3 PFC's have failed or loss of communication between the PFC's and ACE's. It can also be selected by disconnecting the PFC switch to DISC.

Question 26

What functions are still available in Secondary and Direct modes?

Answer 26

Full airplane control is available, All Flight Control Surfaces are operable.

Question 27

In Normal mode, what control surface is moved when the pitch trim is applied?

Answer 27

The Elevator is moved, then the Stabilizer is streamlined with the Elevator.

Question 28

If the Stabilizer is shut down, what does the pitch trim do?

Answer 28

It changes the trim reference speed by utilizing the Elevators.

Question 29

Where and when is the stabilizer postion indecation displayed?

Answer 29

o It is displayed on the EICAS and Flight Control Synoptic . o From power up: until 10 sec after gear up OR 60 sec after liftoff. o After landing : any pair of pitch trim switches are used or ground speed less than 40kts. o On the flight Control Synoptic it’s constantly displayed.

Question 30

When does the STAB GREENBAND EICAS massage appear?

Answer 30

o The computed green band disagrees with the pressure transducer data o The 2-transducer value are not within the set tolerance o Either transducer has failed

Question 31

What does the stabilizer green band compare for the correct stab trim?

Answer 31

It compares the FMC calculated stab trim data and the pressure transducer data.

Question 32

What is the default range of the stab green band?

Answer 32

The green band is shown from 4 to 9 units.

Question 33

How does the stall protection system operate?

Answer 33

The system limits the speed at which the airplane can be trimmed.

Question 34

Does the B787 have asymmetry for loss of thrust?

Answer 34

Yes, the Roll and Yaw asymmetry is controlled by the flight control system. Automatic rudder input is provided, and the rudder pedals move to give feedback to the pilots.

Question 35

In flight, what does movement of the rudder pedals command in normal mode?

Answer 35

It commands a sideslip maneuver, which commands a rudder input.

Question 36

How does the flight control system maintain yaw on ground?

Answer 36

On ground and speed above 60 kts the system commands rudder to counter the yaw due to an engine failure.

Question 37

After initial input, how does the system offload any lateral control input?

Answer 37

The system transfers any steady state lateral control input to the rudder, resulting in a small side slip.

Question 38

What is the wheel to rudder cross-tie and when is it available?

Answer 38

o Its available in secondary and direct mode. o It reduces maximum side slip and fin loads.

Question 39

What provides turn co-ordination and Dutch roll damping in the normal mode?

Answer 39

Roll/Yaw control laws.

Question 40

How many rudder trim rates are available?

Answer 40

2 rates, a low rate, and a high rate.

Question 41

When are any manual rudder trim inputs automatically zeroed?

Answer 41

o During the takeoff roll when ground speed exceeds 30 kts. o During Landing when the airplane transitions from air mode to ground mode.

Question 42

Where is rudder trim displayed?

Answer 42

On the EICAS and on the synoptic page.

Question 43

In secondary mode, rudder pedals sends what command to the rudder?

Answer 43

It commands a rudder deflection instead of a maneuver command.

Question 44

What is the purpose of the Rudder Ratio Changer? What is it based on in Secondary and Direct mode?

Answer 44

o It automatically reduces the sideslip command as airspeed increases, while pedal forces do not change. o In Secondary and Direct mode, the rudder ratio is based on flap position.

Question 45

What is auto drag and when is it used?

Answer 45

o It deflects the ailerons upward and raises the 2 most outboard spoilers, while maintaining airspeed, to assist in glideslope/glidepath capture when the airplane is on or above the vertical path. o Autodrag also functions when the aircraft carries out an approach in V/S or FPA mode. o It is available ONLY in the landing configuration flap 25 or 30 and the thrust levers are at idle . o The deflection is gradually removed below 500' AGL. o Available in normal mode only.

Question 46

Which control surfaces are locked out at high speed?

Answer 46

The ailerons are locked out. Flaps & Slats are also locked out above 260 kts.

Question 47

Are all spoilers hydraulicly controlled?

Answer 47

No, 2 pairs are electrically controlled.

Question 48

When will the speed brake retract automatically ?

Answer 48

o On the ground, when either thrust, levers move to take off range, or o On the ground, if there is transition to in the air, or o In the air, when either thrust lever is beyond 70% full travel

Question 49

When will the speed brakes automatically extend?

Answer 49

o When not ARMED: ▪ On ground, with ground speed above 85 kts and both thrust levers previously in takeoff range, then moved to IDLE range ( rejected Takeoff ). ▪ On ground when both reverse levers are moved to reverse IDLE. o When ARMED: ▪ On landing when main gear trucks untilt and both thrust levers are not in takeoff range.

Question 50

Describe the Cruise Flaps function?

Answer 50

The system is fully automated. It moves the flaps, ailerons, flaperons and spoilers to enhance the wing camber and reduce drag. They are only available in normal mode above 25000' between 0.54 Mach & 0.87 Mach.

Question 51

When will the EICAS advisory massage (Cruise Flaps SYS) display?

Answer 51

If the system fails with the flaps in an increased drag condition.

Question 52

What Hydraulic systems power the Flight Controls?

Answer 52

All 3 Hydraulic systems.

Question 53

When is Flap Load Relief available?

Answer 53

In the primary mode, the Flap load relief system protects the flaps from excessive air loads. If a flap airspeed placard limits are exceeded with flaps in the 15 through 30 position , LOAD RELIEF is dislayed and the flap automatically retract to a safe position appropriate to the airspeed.

Question 54

When is Slat Load Relief available?

Answer 54

It is available in Secondary mode, If airspeed exceeds 240 kts with Slats fully extended, they retract to the MID position. Then return to fully extended when speed is below 240 kts.

Question 55

What is the Slats and Flaps sequence?

Answer 55

o Flaps 1: Slats MID, Flaps 0 o Flaps 5,10,15,17,18 and 20: Slats MID, Flaps to selected position. o Flaps 25: Slats FULL , Flaps do not move. o Flaps 30: Slats FULL, Flaps Landing position.

Question 56

How are the Alternate Flaps/Slats powered? What is the maximum extension available?

Answer 56

By the 3 position Alternate Flap Selector. Slats MID position , Flaps 20.

Question 57

In the slats and flaps alternate mode what kind of protection is lost?

Answer 57

o Asymmetry/skew and un commanded motion protection. o Slat autogap and pregap. o Flaps and slats load relief.

Question 58

What is the difference between slat autogap and slat pregap?

Answer 58

o Autogap: Available in primary mode when the slats are middle position and speed is below 240 knots . At high angle of attack ( AOA ), autogap fully extends the slats to increase the wing camber, thus increasing the lift and margin to stall . The slats return to the middle position after angle of attack decreases. The autogap trip threshold is a function of Angle of attack ( AOA ) , Airspeed and Flap position. o Pregap: In the secondary mode the system is too slow to respond to an autogap request , so a pregap function exists. The slats automatically move to the fully extended position from middle position when the flaps lever is not UP and the speed is less than 240 kts. The slats remain in the extended position until the flap lever is the UP position or airspeed is above 240 KIAS .