A320 GEN FAULT and the IDG Disconnect: Which Control Belongs to Which Failure

What triggers an ELEC GEN 1(2) FAULT on the A320?

𝗘𝗟𝗘𝗖 𝗚𝗘𝗡 𝟭(𝟮) 𝗙𝗔𝗨𝗟𝗧 triggers when the associated generator control unit initiates a protection trip, or when the line contactor is open with the associated GEN pushbutton set to ON.

Those are two distinct conditions, and the second one is defined by what it excludes. A line contactor open with the pushbutton ON is a fault. A line contactor open because the crew selected the pushbutton OFF is 𝗻𝗼𝘁, and the aircraft distinguishes between them. The GEN 1(2) FAULT light on the overhead panel follows the same logic: it comes on if the associated generator control unit trips the generator, or if the line contactor opens except when the GEN pushbutton is selected OFF.

Can you reset an A320 engine generator in flight?

There is a published recovery attempt. The ECAM procedure for ELEC GEN 1(2) FAULT directs:

1. GEN affected OFF then ON
2. If unsuccessful, GEN affected OFF
3. If available, the APU may be started and the APU generator used

The recovery attempt is not the same as a guaranteed recovery, and there is a published limit that is not on the ECAM.

The correct answer on an oral is: follow ECAM, GEN affected OFF THEN ON; if unsuccessful, GEN affected OFF; then consider starting the APU and using the APU GEN if available.

Selecting the GEN pushbutton OFF is what makes the recovery attempt possible. With the pushbutton selected off, the generator field is de-energized, the line contactor opens, and the fault circuit is reset. The OFF-then-ON sequence is a commanded logic reset through a defined path, not a hopeful power cycle.

Should you press the IDG pushbutton for a GEN FAULT?

𝗡𝗼. The IDG pushbutton is not part of the ELEC GEN 1(2) FAULT procedure.

A generator fault is handled through the ECAM actions on the generator control itself. The IDG pushbutton performs a mechanical disconnect and belongs to a different alert. Reach for it only when the ECAM action for ELEC IDG 1(2) OIL LO PR/OVHT directs IDG affected OFF.

This is a common trap because a generator fault feels like a generator problem and the guarded IDG pushbutton sits nearby, apparently offering a more decisive remedy. Pressing it would create an irreversible maintenance item in response to a fault that has its own published procedure.

What does the IDG pushbutton do on the A320?

Pressing the guarded 𝗜𝗗𝗚 𝟭(𝟮) pushbutton disconnects the Integrated Drive Generator from its driveshaft.

The pushbuttons are normally springloaded out and sit under guards, which is the design signalling how the action is intended to be treated. There is one guarded pushbutton per engine, IDG 1 and IDG 2.

This is a mechanical action rather than an electrical selection. It is not a generator reset and it does not clear a fault condition on the generator control side.

What are the published limits on disconnecting the A320 IDG?

There are two constraints on the action itself and one on how the pushbutton is operated.

The published technique is to press the pushbutton until the 𝗚𝗘𝗡 𝗙𝗔𝗨𝗟𝗧 𝗹𝗶𝗴𝗵𝘁 comes on, but not for more than three seconds. The 𝗜𝗗𝗚 𝗙𝗔𝗨𝗟𝗧 𝗹𝗶𝗴𝗵𝘁 goes off when the IDG is disconnected.

So there is a confirmation cue built into the procedure. You are not pressing and hoping. The GEN FAULT light coming on is the signal to release, and the IDG FAULT light extinguishing confirms the disconnection took effect.

What do the A320 IDG oil temperature thresholds mean?

There are three numbers and they form a ladder.

1. Above 147 °C, at or below 180 °C - IDG oil outlet temperature indication pulses for an advisory. The earliest and quietest indication.
2. Above 180 °C - IDG FAULT light comes on for oil outlet overheat. Also comes on for low IDG oil pressure. The low-pressure FAULT light condition is inhibited at low engine speed: N2 below 14 percent.
3. 200 °C - Automatic thermal disconnection occurs. The aircraft stops waiting for the crew and disconnects the drive itself.

Advisory pulse, then FAULT light, then automatic disconnection. A candidate who can walk that ladder in order has demonstrably read the chapter rather than a summary of it.

Which IDG alerts actually direct a disconnect?

Only 𝗘𝗟𝗘𝗖 𝗜𝗗𝗚 𝟭(𝟮) 𝗢𝗜𝗟 𝗟𝗢 𝗣𝗥/𝗢𝗩𝗛𝗧 directs IDG affected OFF.

Treating any IDG oil indication as a reason to disconnect is too broad. The specific alert matters.

What happens automatically when one A320 engine generator fails?

After failure of one engine generator, the system automatically replaces the failed generator with the APU generator, 𝗶𝗳 𝗮𝘃𝗮𝗶𝗹𝗮𝗯𝗹𝗲, or with the other engine generator. The APU generator does not start itself; the condition is that it is available.

The galley shedding depends on phase and source: in flight when only one generator is operating, or on the ground when the aircraft is supplied by one engine generator only. All galleys are available on the ground when the APU generator or external power is supplying power. With the Galley Load Automatic Shedding function fitted, all the galley load can be automatically shed, including the secondary galley.

The bus tie contactors reconfigure automatically. In 𝗕𝗨𝗦 𝗧𝗜𝗘 𝗔𝗨𝗧𝗢, the bus tie contactors automatically open or close to maintain power supply to AC BUS 1 and AC BUS 2. One bus tie contactor is closed when one engine generator supplies its associated AC BUS and the APU generator or external power supplies the other side. Both are closed during single-engine operation, operation on the APU generator, or external power supply.

What is the GEN 1 LINE pushbutton for?

The 𝗚𝗘𝗡 𝟭 𝗟𝗜𝗡𝗘 pushbutton is on the 𝗘𝗠𝗘𝗥 𝗘𝗟𝗘𝗖 𝗣𝗪𝗥 panel rather than the main electrical panel. With GEN 1 LINE selected OFF, the GEN 1 line contactor opens and the AC BUS 1 channel is supplied from GEN 2 through the bus tie contactors. It appears in the smoke drill.

If the aircraft finds the control abnormally OFF, the alert is crew awareness and the crew is directed to set the GEN 1 LINE pushbutton to ON.