Control laws, Hyd and flight controls Flashcards
Flight computers
3 PRIMs - PRIMary
3 SECs - SECondary
1 Computer of ANY type is capable of controlling the AC in all phases of flight
Flight computer inputs
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)
Flight computer main functions
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)
Normal control laws
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
LF Prot (normal law)
Clean: -1 to 2.5 g
Config: 0 to 2 g
Pitch prot (normal law)
25-30 degrees up depending on config
15 degrees down
FD disappears at 25 degrees up and 13 degrees down
High AOA (normal law)
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
High speed prot (normal law)
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)
Bank angle (normal law)
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)
Alt law general
Side-stick controls generally the same as normal
Most protections lost - some replaced by stabilities
AP/AT MAY be operative
Alt law protections
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)
Direct Law general
Direct side-stick to control surface relationship
No AP or auto pitch trim
No protections
Overspeed and stall warnings remain
Back up control (lose all PRIMs and SECs)
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
List the main flight controls
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)
Slats general
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
SFCCs
2 SFCCs - each has 1 flap and 1 slat control
Flap auto functions
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
Slats and Alpha lock
Inhibits slats retraction to zero at high AOA or at low speed.
SLATS/FLAPS lever has a cruise baulk function
If speed > VFE config 1 or above 22,000’, flaps/slats maintained in clean even in case of inadvertent flap lever movement
Ground spoilers
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
Roll spoilers
Spoilers 3-8
Speed brakes
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
Servo control
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
AT limits/protections (normal law)
Speed limit: VLS to VMax -5
Hydraulics overview
Green (left engines) and Yellow (right engines) systems + redundant elec system
The 2 systems are completely separate
Green/Yellow systems
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
Hyd systems and Flight controls
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)
Hydraulic actuator types
Conventional: powered by Green and Yellow
EHA: Powered electrically only
EBHA: Normally G + Y, but with electric back-up as required
LEHGS - Local electro-hydro generating system
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
Dual Hydraulic Failure
AC remains fully controllable in alternate law with AP on
