Flight Controls - STAB & RUDDER

Question 1

Flight Controls

At approximately which ground speed does the rudder become aerodynamically effective during take off ?

Answer 1

60 kts

Question 2

Flight Controls

Which automatic pitch compensation are lost in secondary and direct modes ?

Answer 2

• flap and speedbrake configuration changes
• gear configuration changes
• thrust changes
• turns to 30° bank angle
• turbulence

Question 3

Flight Controls

How is the stabilizer moved ?

Answer 3

Using an electric control unit powered by the L2 and R2 AC buses

Question 4

Flight Controls

When is the stabilizer position indication removed from EICAS ?

Answer 4

• gear up for 10 seconds
• or 60 seconds after liftoff
  (Same as rudder indication)

Question 5

Flight Controls

After landing, when is the stabilizer position indication automatically displayed on the EICAS ?

Answer 5

• any pair of pitch trim switches are used (primary or alternate)
• or ground speed is less than 40 kts

Question 6

Flight Controls

Take off trim range :
What is the default green band range ?

Answer 6

A default green band is displayed from 4 to 9 units prior to performance data being entered into the FMC.

Question 7

Flight Controls

When is the EICAS advisory message STAB GREENBAND displayed ?

Answer 7

• Computed green band disagrees with pressure transducer data, or
• The two transducer values are not within the set tolerance, or
• Either transducer has failed.

Question 8

Flight Controls

What do the stabilizer cutout switches do ?

Answer 8

They cut out the electric power to their respective stabilizer channels L2 or R2.

Question 9

Flight Controls

If the stabilizer has failed or is shutdown while in normal mode, is pitch trim still available ?

Answer 9

YES, through the elevators.

Question 10

Flight Controls

What does the column cutout function do ?

Answer 10

It is designed to stop the effects of uncommended pitch trim input from jammed or failed pitch trim switches.

Question 11

Flight Controls

How does the column cutout function work ?

Answer 11

Pitch trim command from either primary or alternate trim switches is opposed by either control column for more than two seconds ➔ the column cutout function disables the specific pitch trim switch commands until the switch input indicates no trim input.
If that function remains active for more than 20 seconds :
- the flight control system reverts to direct mode
- the uncommanded input is removed by system shutdown
- The STABILIZER L2/R2 EICAS advisory is displayed.

Question 12

Flight Controls

Is the Pitch Control cutout function ever deactivated ?

Answer 12

YES, on the ground to allow trimming nose down stabilizer with aft column input during a touch and go.

Question 13

Flight Controls

Are the Primary pitch trim switches ever inhibited ?

Answer 13

YES : when the auto pilot is engaged.

Question 14

Flight Controls

In normal mode, how do the Primary pitch trim switches operate on the ground ?

Answer 14

They move the stabilizer directly.

Alternate pitch trim switches operate the same way

Question 15

Flight Controls

In normal mode, how do the Primary pitch trim switches operate in flight ?

Answer 15

They command the PFCs to change the trim reference speed.
They first move the elevators to achieve the trim change before moving to stabilizer to streamline the elevator.
(Alternate pitch trim switches operate the same way)

Question 16

Flight Controls

In the secondary or direct modes how do the Primary pitch trim switches operate ?

Answer 16

They operate the same on the ground and in-flight, by directly moving the stabilizer.
(Alternate pitch trim switches operate the same way)

Question 17

Flight Controls

Who has priority between Alternate and Primary pitch trim switches ?

Answer 17

Alternate pitch trim commands have priority over Primary pitch trim commands in all flight control modes.

Question 18

Flight Controls

What does pitch envelope protection include ?

Answer 18

• Overspeed protection

- Stall protection

Question 19

Flight Controls

Is tail strike protection activation apparent ?

Answer 19

NO, activation of tailstrike protection does not provide feedback to the control column.

Question 20

Flight Controls

If tail strike protection is activated, will take off performance be affected ?

Answer 20

NO

Question 21

Flight Controls

In normal mode, do the rudder pedals position the rudder directly ?

Answer 21

No, they command a sideslip maneuver with the sideslip angle dependent on pedal displacement.
The flight control system will then position the rudder to generate the commanded maneuver.

Question 22

Flight Controls

What automatically reduces the side-slip command, for a given pedal input, as airspeed increases ?

Answer 22

The rudder ratio changer.

Question 23

Flight Controls

In secondary and direct modes, do the rudder pedals position to rudder directly ?

Answer 23

Yes, the rudder pedals command a proportional rudder deflection, with different response from pedal inputs when flaps are up or not.
(less response when flaps are up)

Question 24

Flight Controls

Which flight control modes allow manual rudder trim operations ?

Answer 24

All three

Question 25

Flight Controls

When is manual rudder trim inhibited ?

Answer 25

• With the auto pilot yaw (LAND3) engaged on approach,

* Above 30 kts during take-off roll until airborne.

Question 26

Flight Controls

When does rudder position on EICAS normally blank ?

Answer 26

• Gear up for 10 seconds

- Or 60 seconds after liftoff

Question 27

Flight Controls

How is STALL protection provided?

Answer 27

Nose-UP TRIM is inhibited.