Flight Control Laws and Protections Flashcards
(49 cards)
What is SRS?
Speed Reference System.
Controls speed via elevators.
This speed is appropriate to the phase of flight. There’s SRS T/O and SRS G/A, which are very similar.
Target speed for SRS T/O: V2 which blends into V2+10
Target speed for OEI SRS TO: Current speed, limited V2 to V2+15 (so if EFATO, speed target V2)
Target speed for SRS G/A: Speed at engagement or VAPP, WIG
It is also useful for windshear as it has protections built in for pitch which are slightly less than normal pitch protections and a protection that ensures a minimum rate of climb
How many flight control computers do we have and what do they do?
2 x FAC
2 x ELAC
3 x SEC {Lots of sex…}
FAC
Rudder, rudder trim, yaw damper, characteristic speeds, protection speeds, speed tape and speed trend arrow, low energy alert, windshear, beta target
ELAC - Elevator Aileron Computer
Normal elevator/stabiliser control, aileron control
SEC - Spoiler Elevator Computer
Spoiler control, standby elevator/stabiliser control
When is Load Factor protection active?
What are the limits?
What’s the benefit of Load Factor protection?
Normal and alternate law
+2.5g to -1g clean
+2g to 0g other configurations
Allows pilot to full back stick instinctively e.g. GPWS
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)
No bank angle protection
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
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
Pitch attitude protection limitations?
Nose Up
30º - CONF 0, 1, 2, 3
25º - CONF FULL
Nose Down
-15º
At what bank angle does the FD disappear?
45º
If high speed protection is active, with full lateral sidestick, what will the maximum angle of bank be?
40º
What is the only protection you’ll always have in alternate law, regardless of failure?
Load Factor Limitation
What does the sidestick demand in pitch in normal law?
Load Factor demand
Describe what happens in flare mode
Passing 50’ RA (100’ A321) 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. Consequently, a gentle nose up action is required by the pilot.
When does Ground Mode change to Flight Mode in pitch?
What is the difference between Ground Mode and Flight Mode?
Flight mode blends in about 5s after lift off when pitch exceeds 8º.
In Ground Mode sidestick has a direct relationship with Elevator, whereas in Flight Mode it is a Load Factor demand.
I’m normal law, when does auto trim stop functioning?
When manual trim input
Rad alt below 50ft
Load factors below 0.5g
What is lateral ground mode?
Roll is direct relationship to sidestick input
During takeoff max deflection of ailerons and spoilers reduce
What’s the difference between Normal and Alternate Law? Pitch, roll, landing, protections and speed?
Pitch - unchanged - Load Factor Demand
Roll - direct relationship
Landing - no flare law, landing Direct Law CONF 3
Protections - Load Factor unaffected, High Speed and High 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 Reduced Protections?
Depends on system downgrades
With protections offers High and Low speed stabilities
Describe High Speed stability
Alternate Law - may or may not be available depending on failure.
Above VMO/MMO a/c pitches up gently but can be overridden by pilot.
Aural Overspeed Warning is available.
