27-20 Flight Control Laws Flashcards
When is load factor protection active? What are the limits?
Normal and alternate law
+2.5g to -1g clean
+2g to 0g other configurations
What does the low speed tape look like in other laws except normal?
VLS in amber
VSW at top of black and red section
What protections are reduced in alternate law?
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
Normal flight envelope, what is max limit for bank angle?
67 degrees
Above what angle of bank is aft sidestick pressure required in a turn?
33 degrees
When is alpha floor available?
Normal law
From lift-off to 100ft RA before landing
Which protection has priority over all others?
High AOA
What does the low speed tape look like in normal law?
VLS in amber outline box
VAprot top of amber and black section
VAmax top of red section
If angle of attack protection is active, and the pilot maintains full sidestick deflection, what is the maximum bank angle?
45 degrees
If high speed protection is operative, what will the bank angle return to if sidestick released?
0 degrees
What is alpha floor a function of?
Autothrust
Pitch attitude protection limitations?
Nose Up
30º - CONF 0, 1, 2, 3
25º - CONF FULL
Nose Down
-15º
Normal flight envelope, what will the bank angle return to if sidestick is released above this angle?
33 degrees
Above which pitch and bank angles do flight directors disappear?
25deg NU (returns at 22deg NU)
-13deg ND (returns at -10deg ND)
45deg AOB (AP disconnects above this, returns at 40deg AOB)
If high speed protection is active, with full lateral sidestick, what will the maximum angle of bank be?
40 degrees
What is the only protection you’ll always have in alternate law, regardless of failure?
Load factor limitation
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?
5 seconds for pitch and 0.5 seconds for lateral
What does the sidestick demand in pitch in normal law?
Load factor
Describe what happens in flare mode
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.
What is ground mode?
Ground mode is direct sidestick to elevator relationship. During Take off, max elevator deflection reduces to 20* at 75kts
When does ground mode change to flight mode?
What is flight mode?
Flight mode blends in about 5s after lift off when pitch exceeds 8*
Sidestick demands load factor
I’m normal law, when does auto trim stop functioning?
When manual trim input
Rad alt below 50ft
Load factors below 0.5g
How can you disconnect the AP using flight controls only?
Forcefully moving the flight controls. Pitch attitude protection is inhibited
What is lateral ground mode?
Roll is direct relationship to sidestick input
During takeoff max deflection of ailerons and spoilers reduce
Max bank angle in normal law?
67*
Max roll rate in normal law?
15* per second
What changes to the control laws and protections in alternate law? Pitch, roll, landing, protections and speed?
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
What’s the difference between Alternate Law with/without protections?
Depends on system downgrades
With protections offers high and low speed stabilities
Describe high speed stability?
At usual high speed protection activation, a/c pitches up gently but can be overridden by pilot
Describe AoA stability?
Approx 10kts above stall warner, a/c produces nose down pitch. Pilot can override this
How does PFD annunciation direct law?
Annunciates USE MAN PITCH TRIM in amber
What is mechanical back up?
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
