A320 Engine Questions

Each FADEC is a dual channel (A&B) computer providing full engine management.

• True.
• False.

Explanation: Each FADEC has two-channel redundancy (channel A and channel B), with one channel active and the other in standby — if the active channel fails, the other automatically takes control, giving full engine management authority throughout.

Engines - FADEC (General)

The FADEC has control during a manual engine start sequence except for:

• The high pressure fuel valve.
• The start valve.
• An automatic abort.

Explanation: During a manual start the FADEC still opens and closes the start valve and the HP fuel valve on the crew's cues, and closes the valve/cuts ignition automatically at 50% N2 — what it does NOT have is authority to abort the start on its own initiative (except the one narrow on-ground EGT-overlimit case), unlike an automatic start where it actively monitors for a hot start, stall, or no-light-off and aborts accordingly.

Engines - Ignition and Starting (Manual Starting)

In addition to when the engine is operating, when else will the FADEC be powered?

• When the FADEC GND PWR pb on the maintenance panel is depressed, or the ENG MASTER switch is placed to ON.
• When the FADEC control switch is placed to the IGN/START position.
• For five minutes after electrical power is applied to the aircraft, when the FADEC GND PWR pb on the maintenance panel is depressed, or when the ENG MODE control switch is placed to IGN/START position.
• As long as electrical power is established on the aircraft, the FADEC is powered.

Explanation: The FADEC is also electrically powered for the first 5 minutes after the aircraft's electrical network is energized, whenever the FADEC GND PWR pushbutton on the maintenance panel is pressed, or when the ENG MODE selector is placed to IGN/START — on top of its own magnetic alternator supplying it once the engine is running.

Engines - FADEC (General) / Controls and Indicators (Maintenance Panel)

For reverser actuation, the left engine uses ____ hydraulic system pressure and the right engine uses _____ hydraulic system pressure.

• Green - Yellow.
• Yellow - Blue.
• Yellow - Green.
• Blue - Green.

Explanation: A hydraulic door jack deploys each thrust reverser, and the green circuit powers ENG 1's (the left engine's) reverser doors while the yellow circuit powers ENG 2's (the right engine's).

Engines - Thrust Reverser System (General)

Does the FADEC provide EGT limit protection constantly?

• Yes, in all phases of flight.
• No, EGT limit protection is only available during ground auto starts.
• No, EGT limit protection is only available during ground auto starts and single-engine operations.

Explanation: The FADEC's engine-limit protection functions list EGT monitoring specifically "during engine start" — separate from the N1/N2 overspeed protections, which apply continuously — so EGT limit protection is tied to the ground automatic-start sequence rather than being active throughout every phase of flight.

Engines - FADEC (Functions, Protection Against Engine Exceeding Limits)

When the A/THR system is in use:

• The throttles move automatically according to FADEC commands.
• The throttles can only be moved manually.
• The throttles will move when the A/THR p/b is used.

Explanation: The A320's thrust levers don't move by themselves under any autothrust command — the crew always moves them manually, whether or not A/THR is engaged; A/THR simply computes thrust within whatever range the lever position allows.

Auto Flight - Autothrust (Activation, Effects of Thrust Lever Movement)

How many FADEC’s are installed in the aircraft?

• Two, one per engine.
• One, with two Engine Control Units (ECU).
• Two per engine.
• Two, one is the active FADEC and the other is a standby.

Explanation: There are two FADECs installed, one dedicated to each engine — each is a self-contained, two-channel (A/B) unit providing full authority digital control for its own powerplant.

Engines - FADEC (General)

Holding the instinctive disconnect push button’s for more than fifteen seconds will:

• Disengage the A/THR (including Alpha Floor) until below 1000 feet AGL for the remainder of the flight.
• Disengage the A/THR (including Alpha Floor) until below 500 feet AGL for the remainder of the flight.
• Disengage the A/THR (excluding Alpha Floor) for the remainder of the flight.
• Disengage the A/THR (including Alpha Floor) for the remainder of the flight.

Explanation: That 15-second hold on the instinctive disconnect pushbutton takes out A/THR and Alpha Floor together, unconditionally, for the remainder of the flight — there's no altitude-based exception that brings either function back.

Auto Flight - Autothrust (A/THR Disconnection)