```html Airbus A320 Fly-By-Wire Redundancy & Control Law Explorer

A320 FBW Control Law & Redundancy Explorer

A320 Architecture v2.4
Fault Injection & Failure Presets
Flight Control Computers
ELAC 1 Elev/Ail L1/R1
ELAC 2 Elev/Ail L2/R2
SEC 1 Spoilers / Elev
SEC 2 Spoilers / Elev
SEC 3 Spoilers 1 & 2
FAC 1 Yaw Trim/Limiter
FAC 2 Rudder Backup
Hydraulic Systems (3000 PSI)
GREEN HYD Eng 1 Pump
BLUE HYD Elec / RAT
YELLOW HYD Eng 2 / Elec
Interactive Sidestick Test
PITCH: 0% ROLL: 0%
Active Reconfiguration & Surface Architecture Normal Law
Primary Flight Control State
Normal Law (C* Pitch Rate + Load Factor Demand)
Full flight envelope protections active: Pitch attitude protection, High AOA (α-prot/α-max), High speed protection, Bank angle protection (67° max), Load factor limits (+2.5g / -1.0g).
L AIL R AIL L ELEV R ELEV RUDDER THS AUTO TRIM
Flight Envelope Protections Availability
Pitch Attitude Prot
+30° / -15°
High AOA / α-Prot
Active (α-Max)
Bank Angle Prot
Max 67°
High Speed Prot
Active (VMO/MMO)
Load Factor Lim
+2.5g / -1.0g
ECAM Warning & System Monitor
F/CTL ECAM MEMO 10:41:14 UTC
ALL SYSTEMS NORMAL
-----------------------------
PITCH LAW : NORMAL
ROLL LAW : NORMAL
YAW LAW : NORMAL
A320 FBW Control Law Rules & Architecture

1. ELAC vs. SEC vs. FAC Responsibilities

• ELAC (Elevator Aileron Computer): Primary pitch control (elevators & THS) and roll via ailerons.
• SEC (Spoiler Elevator Computer): Spoilers, speedbrakes, plus elevator control fallback.
• FAC (Flight Augmentation Computer): Yaw damper, rudder trim, travel limit, and speed scales.

2. Law Degradation Sequence

• Normal Law: Full flight envelope protections active. Sidestick demands g-load (pitch) and roll rate.
• Alternate Law: Occurs when multiple computers or hydraulics fail. Load factor demand remains in pitch, but roll becomes direct stick-to-surface demand. Envelope protections reduced or lost.
• Direct Law: Fixed direct stick-to-surface deflection. Manual pitch trim required (THS auto-trim lost).
• Mechanical Backup: Complete loss of computers/electrical. Pitch via manual pitch trim wheel, Yaw via rudder pedals.

Air India Flight Control Incident Context: Dual ELAC momentary transients or fault cascades trigger automatic reconfiguration from Normal Law to Alternate Law. Understanding how control surfaces failover between Blue, Green, and Yellow hydraulic circuits is vital for flight safety analysis.
Active State Summary: Law = NORMAL LAW | Computers Online = 7/7 | Hyd Systems = 3/3