LABOX

Caution Beeper when pushing APU Gen1/2

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Hi everybody,

I have a question regarding the shutdown procedure.

Everytime I "push both overhead APU generator switches to transfer power from the engine generators before shutdown" (as per the tutorial) the caution beeper is blaring at me and the upper EICAS is showing the warnings:

 

ELEC GEN OFF 4

ELEC GEN OFF 3

ELEC GEN OFF 2

ELEC GEN OFF 1

 

Am I doing something wrong or is this just the way the aircraft behaves?

Any help is greatly appreciated!

 

Best, Arne

 

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Looking at the FCOM, those EICAS messages will give you that aural warning, so looks like it's supposed to do that. As for the messages actually coming up, looking at the FCOM, it's supposed to do that.

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It depends on what Service Bulletins have been carried out on the aircraft:

(From an old Fault Isolation Manual)
 CAUTION: on airplanes with registrations xxxxxx pre- service bulletin 747-434-2707 and post service bulletin 747-34-27-2793

 ADVISORY: on airplane with registration xxxxxx post- service bulletin 747-34-2707 and pre- service bulletin 747-34-2793

Advisories have no aural warnings.

I don't know if all 747-400s had this service bulletin carried out. It may have been optional or compulsory.

Cheers

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Thanks for your replies! So, I´m not doing anything wrong here? I´m just asking because these aural warnings are often triggered by a fault, aren´t they?

13 minutes ago, Captain Kevin said:

I was looking at the FCOM section 6.30.2 and 6.20.3.

Yeah, I found these too, but couldn´t figure out whether I made a mistake or not...

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Our FCOM says the message is an Advisory. However...

When I used to do engine ground test runs, I would deselect the engine GCBs prior to engine start (and use APU gens throughout the run)... Shortly after engine start, the ELEC GEN OFF Caution message for the respective engine would appear and the aural would sound. 

ELEC GEN OFF message is an indication that the GCB is open (and the engine is running).

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29 minutes ago, LABOX said:

Thanks for your replies! So, I´m not doing anything wrong here? I´m just asking because these aural warnings are often triggered by a fault, aren´t they?

Not sure how you could be doing anything wrong when I've just confirmed that it's supposed to do that. Have a look at the FCOM if you don't believe me. The aural warnings aren't necessarily triggered by a fault, per se. You could have the altitude alert trigger it, and that's not exactly a fault. That's just telling you you've deviated more than 300 feet from the altitude you punched into the MCP. You could have low airspeed trigger it, and that's not exactly a fault, either. That's just telling you....WEL....your airspeed is low. You could have the crew alert monitor trigger it if you have that option enabled, and that's not really a fault. That's just a situation where the plane has detected no activity and is trying to get your attention to make sure you're actually there. You could have the speedbrake extended message trigger it, and that's not really a fault, either. That one's just telling you your speedbrakes are extended when flight conditions don't warrant it.

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9 minutes ago, Captain Kevin said:

You could have the altitude alert trigger it, and that's not exactly a fault. That's just telling you you've deviated more than 300 feet from the altitude you punched into the MCP. You could have low airspeed trigger it, and that's not exactly a fault, either.

It's a fault.. It's just not an aircraft fault :wink:

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Depends, earlier jets did this, most jets now do not because they have been modified as John said by service bulletin.

When you transfer to APU 1 and APU 2, you get the ELEC GEN OFF 1 2 3 4 alert messages on EICAS, but these are Advisories, so there is no aural.

Then when you shut down, all cautions and the aural beeper are then inhibited when you are on the ground with the Fuel Control Switches in CUTOFF

 

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2 hours ago, Qavion2 said:

It depends on what Service Bulletins have been carried out on the aircraft:

(From an old Fault Isolation Manual)
 CAUTION: on airplanes with registrations xxxxxx pre- service bulletin 747-434-2707 and post service bulletin 747-34-27-2793

 ADVISORY: on airplane with registration xxxxxx post- service bulletin 747-34-2707 and pre- service bulletin 747-34-2793

Advisories have no aural warnings.

I don't know if all 747-400s had this service bulletin carried out. It may have been optional or compulsory.

Cheers

I think a long time ago the jet did give a caution aural when switching to APU power prior to shutdown, but I believe most 400's carried out that service bulletin to change it to advisory message when you get the ELEC GEN messages on transfer of power. Yes, the PMDG livery does give you the aural, most jets now when you get an ELEC GEN message, it is Advisory, not caution...

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39 minutes ago, Captain_Al said:

Then when you shut down, all cautions and the aural beeper are then inhibited when you are on the ground with the Fuel Control Switches in CUTOFF.

Captain Al, only the Caution aural is inhibited :wink:

e.g. Caution messages such as DOOR AFT CARGO and >BRAKE SOURCE still appear on the ground.

Also, the altitude alert Caution aural is not inhibited on the ground (It's a special case). Some books mention that the park brake has to be set, but I can't remember if I confirmed this in real life.

Cheers

JHW.

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3 hours ago, Qavion2 said:

(From an old Fault Isolation Manual)
 CAUTION: on airplanes with registrations xxxxxx pre- service bulletin 747-434-2707 and post service bulletin 747-34-27-2793

Sorry.. a few typos there...

It should read  "CAUTION: on airplanes with registrations xxxxxx pre- service bulletin 747-34-2707 and post service bulletin 747-34-2793

I don't know why the number "34" is used. This usually refers to Navigation equipment.

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1 hour ago, Qavion2 said:

Captain Al, only the Caution aural is inhibited :wink:

e.g. Caution messages such as DOOR AFT CARGO and >BRAKE SOURCE still appear on the ground.

Also, the altitude alert Caution aural is not inhibited on the ground (It's a special case). Some books mention that the park brake has to be set, but I can't remember if I confirmed this in real life.

Cheers

JHW.

I stand corrected, sometimes I type without thinking, that is true...

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7 hours ago, Captain Kevin said:

Not sure how you could be doing anything wrong when I've just confirmed that it's supposed to do that. Have a look at the FCOM if you don't believe me. The aural warnings aren't necessarily triggered by a fault, per se. You could have the altitude alert trigger it, and that's not exactly a fault. That's just telling you you've deviated more than 300 feet from the altitude you punched into the MCP. You could have low airspeed trigger it, and that's not exactly a fault, either. That's just telling you....WEL....your airspeed is low. You could have the crew alert monitor trigger it if you have that option enabled, and that's not really a fault. That's just a situation where the plane has detected no activity and is trying to get your attention to make sure you're actually there. You could have the speedbrake extended message trigger it, and that's not really a fault, either. That one's just telling you your speedbrakes are extended when flight conditions don't warrant it.

Got it ;0) Thanks...

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