27-20 Flight Control Laws

Question 1

When is load factor protection active? What are the limits?

Answer 1

Normal and alternate law

+2.5g to -1g clean
+2g to 0g other configurations

Question 2

What does the low speed tape look like in other laws except normal?

Answer 2

VLS in amber
VSW at top of black and red section

Question 3

What protections are reduced in alternate law?

Answer 3

Load factor limitation similar to normal law.

No pitch attitude protection (Amber Xs)

Low speed stability:
- VSW replaces VAprot and VAmax
- 5-10kt above VSW, a gentle nose down signal is introduced
- Pilot can override this
- Alpha floor is inoperative

High speed stability:
- Above VMO/MMO a nose up demand is introduced
- Pilot can override this

No bank angle protection

Question 4

Normal flight envelope, what is max limit for bank angle?

Answer 4

67 degrees

Question 5

Above what angle of bank is aft sidestick pressure required in a turn?

Answer 5

33 degrees

Question 6

When is alpha floor available?

Answer 6

Normal law

From lift-off to 100ft RA before landing

Question 7

Which protection has priority over all others?

Answer 7

High AOA

Question 8

What does the low speed tape look like in normal law?

Answer 8

VLS in amber outline box
VAprot top of amber and black section
VAmax top of red section

Question 9

If angle of attack protection is active, and the pilot maintains full sidestick deflection, what is the maximum bank angle?

Answer 9

45 degrees

Question 10

If high speed protection is operative, what will the bank angle return to if sidestick released?

Answer 10

0 degrees

Question 11

What is alpha floor a function of?

Answer 11

Autothrust

Question 12

Pitch attitude protection limitations?

Answer 12

Nose Up
30º - CONF 0, 1, 2, 3
25º - CONF FULL

Nose Down
-15º

Question 13

Normal flight envelope, what will the bank angle return to if sidestick is released above this angle?

Answer 13

33 degrees

Question 14

Above which pitch and bank angles do flight directors disappear?

Answer 14

25deg NU (returns at 22deg NU)
-13deg ND (returns at -10deg ND)

45deg AOB (AP disconnects above this, returns at 40deg AOB)

Question 15

If high speed protection is active, with full lateral sidestick, what will the maximum angle of bank be?

Answer 15

40 degrees

Question 16

What is the only protection you’ll always have in alternate law, regardless of failure?

Answer 16

Load factor limitation

Question 17

How long does the aircraft take after the pitch attitude increases above 8 degrees nose up for pitch control and lateral control to blend into flight mode on take off?

Answer 17

5 seconds for pitch and 0.5 seconds for lateral

Question 18

What does the sidestick demand in pitch in normal law?

Answer 18

Load factor

Question 19

Describe what happens in flare mode

Answer 19

Passing 50ft RA on landing, the THS is frozen and flare mode provides a direct stick-to-elevator relationship.

The system memorises the attitude at 50ft, and at 30ft introduces a nose down demand to reduce the pitch to -2 degrees nose down over a period of 8 seconds. Subsequently, a gentle nose up action is required by the pilot.

Question 20

What is ground mode?

Answer 20

Ground mode is direct sidestick to elevator relationship. During Take off, max elevator deflection reduces to 20* at 75kts

Question 21

When does ground mode change to flight mode?

What is flight mode?

Answer 21

Flight mode blends in about 5s after lift off when pitch exceeds 8*
Sidestick demands load factor

Question 22

I’m normal law, when does auto trim stop functioning?

Answer 22

When manual trim input
Rad alt below 50ft
Load factors below 0.5g

Question 23

How can you disconnect the AP using flight controls only?

Answer 23

Forcefully moving the flight controls. Pitch attitude protection is inhibited

Question 24

What is lateral ground mode?

Answer 24

Roll is direct relationship to sidestick input
During takeoff max deflection of ailerons and spoilers reduce

Question 25

Max bank angle in normal law?

Answer 25

67*

Question 26

Max roll rate in normal law?

Answer 26

15* per second

Question 27

What changes to the control laws and protections in alternate law? Pitch, roll, landing, protections and speed?

Answer 27

Pitch…unchanged
Roll…direct relationship
Landing…no flare law, landing direct law conf 3
Protections…load factor unaffected, high speed and AoA are downgraded to stabilities, all other protections lost
Speed…max speed 320kts, no Alpha Floor

Question 28

What’s the difference between Alternate Law with/without protections?

Answer 28

Depends on system downgrades
With protections offers high and low speed stabilities

Question 29

Describe high speed stability?

Answer 29

At usual high speed protection activation, a/c pitches up gently but can be overridden by pilot

Question 30

Describe AoA stability?

Answer 30

Approx 10kts above stall warner, a/c produces nose down pitch. Pilot can override this

Question 31

How does PFD annunciation direct law?

Answer 31

Annunciates USE MAN PITCH TRIM in amber

Question 32

What is mechanical back up?

Answer 32

Loss of all FBW computers as a result of total electrical failure.
Meant to be temporary condition until electrics restored
Use pitch trim for pitch and rudders for roll