Flight Controls & Flight Control Laws (Even/Odd)

Question 1

What type of flight control system does the A320 family aircraft utilize?

Answer 1

Fly-By-Wire system

Question 2

Describe how the flight controls are controlled and activated.

Answer 2

Electrically Controlled and Hydraulically Activated

Question 3

How is NORMAL LAW indicated on the PFD?

Answer 3

• Green “=” for pitch, bank, and over speed limits
• Amber/black (ALPHA PROT) airspeed tape

Question 4

How is ALTERNATE LAW indicated on the PFD?

Answer 4

Amber Xs (indicating lack of NORMAL LAW protections)

Question 5

How is DIRECT LAW indicated on the PFD?

Answer 5

• Amber “USE MANUAL PITCH TRIM”
• Amber Xs (indicating lack of NORMAL LAW protections)

Question 6

How is MECHANICAL BACKUP indicated on the PFD?

Answer 6

• Red “MAN PITCH TRIM ONLY”
• Amber Xs (indicating lack of NORMAL LAW protections)

Question 7

When operating in NORMAL LAW in flight mode, what does the side stick command for pitch and roll?

Answer 7

• Pitch – G load
• Bank – Roll rate

Question 8

What is the significance of the Side Stick Priority (Red Arrow) Light?

Answer 8

The other pilot has gained side stick authority

Question 9

Name the Flight Control Computers and the number of each.

Answer 9

• ELAC – Elevator Aileron Computer (2)
• SEC – Spoiler Elevator Computer (3)
• FAC – Flight Augmentation Computer (2)

Question 10

What does SEC 3 control?

Answer 10

Spoiler Control – one flight spoiler and one ground spoiler on each wing

Question 11

What should happen to the THS after landing?

Answer 11

Reset to zero

Question 12

Describe some of protections a pilot will have in NORMAL LAW?

Answer 12

• High Speed
• High Angle of Attack (AOA) Protection
• Load Factor Limitation +2.5G / -1.0G (+2.0G / 0.0G With Flaps/Slats)
• Pitch Attitude Protections (30° UP / 15° DN)
• Bank Angle Protections (67°)

Question 13

Describe High Speed Protection.

Answer 13

If VMO/MMO plus a predetermined factor is exceeded, the system induces a pitch-up input to limit aircraft speed.

Question 14

What, if anything, can a pilot do to override high-speed protection pitch up?

Answer 14

It is not possible to override a protection while still in NORMAL LAW. In this case, the aircraft would need to be forced into ALTERNATE LAW (by turning 2 ADRs off, for example).

Question 15

What is ALPHA MAX?

Answer 15

The maximum angle of attack allowed in NORMAL LAW, indicated by the top of the red strip on the airspeed scale.

Question 16

How does High Angle of Attack Protection operate?

Answer 16

When the angle of attack exceeds ALPHA PROT, nose up pitch trim ceases and angle of attack is now proportional to side stick deflection, not to exceed ALPHA MAX even with full aft side stick deflection.

Question 17

What protections and stabilities, if any, does a pilot have in ALTERNATE LAW?

Answer 17

• Load Factor
• High speed stability
• Low speed stability

Question 18

What protections, if any, does a pilot have in DIRECT LAW?

Answer 18

None

Question 19

When, if at all, does flare mode activate in ALTERNATE LAW? Describe the whole process.

Answer 19

There is no flare mode if operating in ALTERNATE LAW. The aircraft proceeds directly from ALTERNATE LAW to DIRECT LAW when the gear is selected down, and flare mode will not be available.

Question 20

If in ALTERNATE LAW, when will the aircraft revert to DIRECT LAW?

Answer 20

If the controls degrade to ALTERNATE LAW for any reason other than recovery from abnormal attitude, DIRECT LAW automatically becomes active with gear extension and autopilots not engaged. In this case, full use of autopilot is recommended until they must be disconnected.

Question 21

When is there a direct relationship between side stick and flight control surface deflection?

Answer 21

• When in DIRECT LAW
• On the ground (Ground Mode)

Question 22

It’s common Airbus philosophy that the Airbus cannot stall in NORMAL LAW. However, there are conditions in which it can. Describe how this can happen.

Answer 22

A good pilot will operate under the philosophy that anything can happen. Preventative systems such as (ALPHA PROT, ALPHA MAX, etc.) could interpret bad data as valid data and subsequently fail to recognize the actual angle of attack or flight path of the airplane. Therefore, it is hard to point to exact scenarios when the Airbus can stall in NORMAL LAW. We need to understand anything is possible and we should recognize stall indications and recover regardless of the active control law.

Question 23

How would the aircraft enter ABNORMAL ATTITUDE LAW?

Answer 23

By exceeding approximately double the NORMAL LAW limits.

Question 24

What is the purpose of ABNORMAL ATTITUDE LAW?

Answer 24

Allows the aircraft to be recovered from an unusual attitude.

Question 25

If the flight crew is flying at 300 knots and they happen to pull full back on the side stick, how high can they pitch up?

Answer 25

30° up

Question 26

If the pilot selects 100 knots on the speed knob, how slow would the aircraft fly if the autopilot and auto thrust are engaged?

Answer 26

VLS

Question 27

Describe, in detail, what would happen if the pilot slowly pulled the thrust levers to idle in Normal Law.

Answer 27

• As airspeed decays, the THS adjusts the pitch attitude to maintain altitude.
• If the angle of attack increases to a threshold value, known as ALPHA PROT, the pitch function of the side stick changes. Stick movement commands a specific angle of attack instead of a G load change.
• Since nose up pitch trim ceases, the pilot must hold continuous back pressure in order to fly slower than the speed for ALPHA PROT.

Question 28

Continuing the scenario above, describe what would happen if the flight crew continued to pull back on the side stick. How slow would the aircraft go?

Answer 28

• The speed corresponding to ALPHA MAX
• With the stick full aft, the elevators will adjust the pitch attitude to maintain a maximum safe angle of attack (ALPHA MAX). This maximum angle of attack, induced by the pilot, is slightly lower than the stall angle of attack; therefore, the aircraft theoretically cannot be stalled in NORMAL LAW.

Question 29

At some point during this demonstration the AUTOTHRUST automatically applies TOGA power. What is this protection, and how does it work?

Answer 29

• ALPHA FLOOR is a function of AUTOTHRUST. It will activate at any airspeed based on angle of attack and automatically apply TOGA thrust regardless of thrust lever position.
• ALPHA FLOOR is available if the AUTOTHRUST is functional (it does not need to be active), an engine is running (not both), and the aircraft is in NORMAL LAW.
• Angle of attack protection does not depend on ALPHA FLOOR to function.
• On NEO aircraft, ALPHA FLOOR is inhibited above M 0.6

Question 30

Describe what would happen if a flight crew attempted to overstress the aircraft while in NORMAL LAW.

Answer 30

• Maneuver protection prevents a pilot from over stressing the aircraft by limiting flight control inputs.
• If G loads become greater than normal, they are displayed in amber on the lower ECAM above the digital clock.
• When the side stick is pushed forward, less than 1G is commanded. A given pitch input always results in the same pitch response regardless of airspeed.
• When the stick is returned to neutral, the new pitch is held constant regardless of airspeed changes.