Control laws, Hyd and flight controls

Question 1

Flight computers

Answer 1

3 PRIMs - PRIMary
3 SECs - SECondary

1 Computer of ANY type is capable of controlling the AC in all phases of flight

Question 2

Flight computer inputs

Answer 2

PRIM and SEC:
ADIRUs
SFCCs
LG ext/retract system (LGERS)
Hydraulic sensors for system status

PRIM only:
Accelerometers/gyros (LF)
Both ISIS (monitor ADRs)
RAs
Fuel quantity and management system ( FQMS: weight and CG)
Weight and balance back-up computer (WBBC: weight and CG)

Question 3

Flight computer main functions

Answer 3

PRIM:
All flight control laws
Load alleviation function (turbulance alleviation to reduce wing bending moment)
Flight envelope protection
Control surfaces
AP, FD, AT

SEC:
Direct law only
Control surfaces
Rudder trim (SEC 1 and 3 only)

Question 4

Normal control laws

Answer 4

Ground:
Roll and Yaw direct sidestick (for FC checks)

Rotation:
Direct relationship in pitch (minimized tailstrike)

Flight law:
LF demand with auto-trim and rate of roll with full envelope protection (roll active from lift-off, pitch progressively over next 5 secs)

Flare:
Direct relationship with full elevator authority (active <100’)

Deterioration:
Prevents hard nose wheel touchdown

Ground law:
After touchdown

Question 5

LF Prot (normal law)

Answer 5

Clean: -1 to 2.5 g
Config: 0 to 2 g

Question 6

Pitch prot (normal law)

Answer 6

25-30 degrees up depending on config
15 degrees down

FD disappears at 25 degrees up and 13 degrees down

Question 7

High AOA (normal law)

Answer 7

Takes precedence over all others.

Active between V alpha prt and V alpha max (barbers pole)

VLS = lowest selectable speed

V alpha prot (top of amber/black barber pole): AP disconnects and pitch trim inhibited - protections WILL MAINTAIN V alpha prot

Alpha floor (between alpha prot and alpha max): TOGA activated

If 1 engine out, only symmetrical engines spool up. If 2 engines inop and provided they aren’t on same wing, alpha floor remains available

Alpha max (top of red): pilot can get down here if he holds the sidestick fully back, but it will not go further. If pilot releases, back to V alpha prot

Question 8

High speed prot (normal law)

Answer 8

VMO + 4

Pitch trim freezes, AP disconnect, max bank angle 45 degrees

Above prot speed, pitch up demanded, AT targets lowest of speed bug or (VMO/MMO)

Question 9

Bank angle (normal law)

Answer 9

67 degrees clean
60 degrees high lift operations
FD disappears after 45 degrees and no auto-trim after 33 degrees

Sidestick release (returns to 33 degrees normally but level if high speed prot active)

Question 10

Alt law general

Answer 10

Side-stick controls generally the same as normal

Most protections lost - some replaced by stabilities

AP/AT MAY be operative

Question 11

Alt law protections

Answer 11

Pitch: lost (amber xx)

BA: lost (amber xx)

High AOA: lost but replaced by low speed stability (nose down added to avoid further speed reduction - VSW on PFD only)

High speed prot: lost and replaced with high speed stability (nose up to reduce speed)

Question 12

Direct Law general

Answer 12

Direct side-stick to control surface relationship

No AP or auto pitch trim

No protections

Overspeed and stall warnings remain

Question 13

Back up control (lose all PRIMs and SECs)

Answer 13

Backup Control Module (BCM) takes over. Controls:

Inner ailerons
Outer elevators
THS
Rudder

BCM powered by two Backup Power Supply (BPS). The BPSs are electrical generators driven by the Yellow and Green hydraulic system respectively

Since normal hyd available, conventional servo controls are available

Question 14

List the main flight controls

Answer 14

3 ailerons per wing (roll)
8 spoilers per wing (roll)
1 THS (pitch)
2 elevators on each side of the horizontal tail plane (pitch)
2 rudders (yaw)

Question 15

Slats general

Answer 15

Slats:
6 slats and 2 nose-droop panels (8 slats) per wing
1 hyd motor (green) and one elec motor (AC ESS) per slat

Flaps:
3 flaps per wing
2 hyd motors (green and yellow) per flap

Question 16

SFCCs

Answer 16

2 SFCCs - each has 1 flap and 1 slat control

Question 17

Flap auto functions

Answer 17

Auto Retraction System (ARS) - In Config 1+F, flaps retracted at 212 kt

Auto Extension System (AES) - in Config 1, flaps 1 extended automatically at 205kt

Flap Load Relief System (FLRS) - retracts flaps to next level up if VFE +2.5 kt. Flaps automatically return to previous position at VFE -2.5 kt. Available for Configs 2, 3 and Full

Question 18

Slats and Alpha lock

Answer 18

Inhibits slats retraction to zero at high AOA or at low speed.

Question 19

SLATS/FLAPS lever has a cruise baulk function

Answer 19

If speed > VFE config 1 or above 22,000’, flaps/slats maintained in clean even in case of inadvertent flap lever movement

Question 20

Ground spoilers

Answer 20

8 per wing

TO: fully extend if armed and RTO >72 kt

Land: armed, at least 3 main gears compressed, TL @ idle: spoilers and ailerons fully extend to dump lift

Get partial extension with 1 main gear compression and TL @ idle

Spoilers will retract if at least 2 TL above CLB detent

Question 21

Roll spoilers

Answer 21

Spoilers 3-8

Question 22

Speed brakes

Answer 22

All spoilers, but 1-2 only partial deflection

Auto-extension when:
Speed >VMO/MMO – 5 kt
AP and A/THR are ON, and
Altitude hold mode is engaged

Auto-retract when:
Alpha protection/low speed stability active, or
GA initiated

Once retracted, the speed brakes remain retracted, even if the conditions have disappeared. To extend the speed brakes again, the lever must be first set to the retracted position for at least 5 s

If 1 faulty, symmetrical one inhibited

Question 23

Servo control

Answer 23

Elevators, ailerons, stabilizers and rudders: 1 active and 1 back-up servo each

Spoilers: single servo only

Each servo driven by either green, yellow or AC elec system

Question 24

AT limits/protections (normal law)

Answer 24

Speed limit: VLS to VMax -5

Question 25

Hydraulics overview

Answer 25

Green (left engines) and Yellow (right engines) systems + redundant elec system

The 2 systems are completely separate

Question 26

Green/Yellow systems

Answer 26

Reservoirs in Pylons 1 (Green) and 4 (Yellow) pressurized by bleed air to prevent cavitation

4 Fire Shut Off valves (closed by pressing Engine Shut Off valve overhead) isolate each engine

4 Engine driven pumps (EDPs; 2 per engine) pressurize each hydraulic system to 5000 psi

2 Elec pumps (per system) power each sys on ground with no engines running (Green - Cargo doors; Yellow - Body Wheel steering [NWS by LEHGS])

Each sys controlled and monitored by a HSMU (Hydraulic System Monitoring Unit - 1 each side)

If one HSMU fails, its associated hydraulic system remains operative

Question 27

Hyd systems and Flight controls

Answer 27

Slats Green only, but pretty much all other Flight Controls powered by Green + Yellow

Some FC controlled by Electro-Hydrostatic Acuators (EHA) and Electrical Back-up Hydraulic Actuators (EBHAs)

Part of the landing gear (wheel braking and nose wheel steering) are powered by Local Electrical Hydraulic Generating Systems (LEHGSs)

Question 28

Hydraulic actuator types

Answer 28

Conventional: powered by Green and Yellow

EHA: Powered electrically only

EBHA: Normally G + Y, but with electric back-up as required

Question 29

LEHGS - Local electro-hydro generating system

Answer 29

Alternative power sources for Braking and NWS - elec driven

Has its own Reservoir and Fire Shut-off Valve

Reservoir filled by either G or Y at 1st engine start

Fire shut off valve then closes before TO to segregate systems from G and Y

Question 30

Dual Hydraulic Failure

Answer 30

AC remains fully controllable in alternate law with AP on