Control Laws

Question 1

Control laws and their characteristics

Answer 1

• Normal law- Pitch: Vertical load factor- Bank: Roll rate• Alternate law- Pitch: Vertical load factor- Bank: Roll rate in ALTN1 / Direct control of ailerons in ALTN2• Direct law, direct relationship between stick and flight control surfaces• Ground law (before lift-off and after touch-down), same as Direct law• Flare law (allow conventional flare):- Pitch: Stick orders a pitch attitude increment to a reference attitude- Bank: Direct control of ailerons

Question 2

Protections in normal law

Answer 2

• Load factor protection• High speed protection• High angle-of-attack protection• Pitch attitude protection• Bank angle protection• Low energy warning

Question 3

Protections in alternate law

Answer 3

• Load factor protection• Bank angle protection (ALTN1 only)• Low speed stability:- VSW replaces αPROT and αMAX- If speed reduces to VSW, AP disconnect and a nose down pitch input is introduced• High speed stability:- Amber dashes replace the Green dashes on speed scale- If speed increases to VMO, AP disconnect and a nose up pitch input is introduced• Aural stall• Overspeed warning

Question 4

Protections in Alternate law without stability

Answer 4

• Load factor protection• Aural stall• Overspeed warning

Question 5

Load factor protection

Answer 5

• Load factor limitation:+ 2.5 g, -1 g in clean configuration+ 2 g, 0 g when slats are extended• Rapid pull-up to 2.5 g is immediately possible.

Question 6

High speed protection

Answer 6

• VMO + 4 kt / MMO+ 0.006,Overspeed Ecam warning• VMO +6 kt / MMO + 0.01, Automatic pitch up applied • VMO + 16 kt / MMO +0.04,Maximum stabilized speed stick maintained nose down

Question 7

High angle-of-attack protection

Answer 7

• VLS: Minimum allowed speed, A/THR in speed mode will not allow speed to drop below VLS even if lower speed is selected• Vα Prot: AP disengages, Auto Pitch trim stops• Vα Floor: TOGA thrust is set automatically• Vα Max: Speed is maintained with full aft stick, speed brake retract if previously extended

Question 8

Pitch attitude protection

Answer 8

• Nose-down, 15°• Nose-up,- 30° in conf 0 to 3 reduced to 25° at low speed- 25° in conf FULL reduced to 20° at low speed

Question 9

Bank angle protection

Answer 9

• Bank angle limited to 67°• Above 33°:- Stick released, aircraft rolls back to 33°- Stick maintained, bank angle maintained• In high speed protection:- Spiral stability is introduced regardless of angle- bank angle is limited to 40°• In high angle-of-attack protection, bank angle is limited to 45°

Question 10

Low energy warningAvailable between 100 ft and 2000 ft RA in Conf 2, 3 and Full

Answer 10

• Aural warning, “SPEED SPEED SPEED”• To stop the warning, increase Thrust

Question 11

Protections in Direct law

Answer 11

• Aural stall• Overspeed warning