Master Caution during Start-Up

During Start-Up (following Memphis Belle's 1.1.0.8 guide), I get a Master Caution warning every time during left engine start-up.

I read that this is because the APU is still running when an engine is providing power.

Is it normal to get this warning because I need the APU ON to start up the right engine.

Thanks.

It's the APU GEN warning light coming on because the APU Generator is running but it does not supply any electricity to the aircraft after the the left engine reaches 52% RPM and it's generator assumes the electrical load.

You can acknowledge the alarm and then switch off the APU and APU generator once you have your engines running at idle as normal.

Thanks for your help.

Hmmm.... so the APU GEN can come off once the left engine is running even if the right engine is still cold?

Interesting! Thanks!

Yes. As soon as the core speed reaches 52% on the left engine, its Integrated Drive Generator starts supplying AC electricity to the AC busses, and the APU Generator is automatically disconnected from said busses.

See here for more info:

http://forums.eagle.ru/showthread.php?p=1169910#post1169910

Yes it's normal. You need the APU for the right engine start but you don't need the APU generator.

Alternatively you can perform a cross-bleed start.

Regarding the APU generator: yes the oil cooling isn't modeled, so you can turn of the APU generator, but: why would you?

To stop the master caution! ;)

But seriously: When it comes to creating a realistic startup-procedure, you'd let the APU + APU GEN running until R ENG is up, unless you want to perform a X-Feed Startup? Then shutting down the APU GEN and about 1-3 minutes after the APU? I read somewhere, that IRL you have a delay between shutting down the APU GEN and the APU, due to cooling of the APU. Is that correct?

I believe the APU Generator is suppossed to trip offline automaticly once the the Left and Right Generators are supplying powering to the Main Bus. I believe the actual APU is left on until the right engine is started and the Right Generator in brought online to reduce the electrical load on the left Generator. Then the APU is shut down.

I believe the APU Generator is suppossed to trip offline automaticly once the the Left and Right Generators are supplying powering to the Main Bus.

Don't think so. If the APU generator would trip offline, power would be cut to the APU oil cooling system.

Don't think so. If the APU generator would trip offline, power would be cut to the APU oil cooling system.

Just because the APU Generator is no longer supplying power to the Main Bus, does not mean its not still charging the batteries and supplying power to the APU oil cooling system according to you.

Anyway the A-10C APU supplies more Bleed air then electrical power anyway, so most pilots leave it on during a hot day to provide more air-condition and as a backup incase of an electrical failure. But it is always shut down during the preflight taxi check.

Don't think so. If the APU generator would trip offline, power would be cut to the APU oil cooling system.

I believe the APU Generator is suppossed to trip offline automaticly once the the Left and Right Generators are supplying powering to the Main Bus.

As soon as the IDG on the left engine kicks in (52% engine core RPM speed), the GCU has contactors simultaneously drop the APU Generator off all AC busses and connect the left engine's IDG to carry the full load of all AC busses. Once the right engine IDG comes online more contactors operate which drop the left IDG from the right AC bus and allow the right IDG to supply the right AC bus. If ground power is suppling power the APU generator is also disconnected from all AC busses. All it does once disconnected is supply bleed air and power to its hydraulics cooling fan.

"You must spread some reputation around before giving it to KLaFaille again."

Isn't that little too much to make master caution scream during that start-up sequence, when nothing is actually wrong?. Master caution is afterall master caution and it's meant to tell pilot something's wrong.

Isn't that little too much to make master caution scream during that start-up sequence, when nothing is actually wrong?. Master caution is afterall master caution and it's meant to tell pilot something's wrong.

It sounds because of the APU GEN lamp being lit on the annunciator panel. The MC is meant to draw a pilots attention to the warning panel when an indicator lights.

I don't know why most of simmers think that master caution is there to tell you something is disastrously wrong with A/C.....

Happens to the best of us.

In the beginning I was head-between-my-legs in the cockpit fumbling for a switch that was supposed to set the SOI as TDW in order for the DRT to find the FRT so I could put the DFE on the DDY, all the while the RWR is screaming bloody murder. Just when I thought that it could not get any better, the Missile warning system kicks into overdrive! At that precise moment the MC decided now was a good time to draw my attention to the Warning Panel to inform me that an obscure indicator light has just lit up........

..................

..........................

I nearly wet myself!

Yeah - It happens to the best of us :pilotfly:

Is it also when you answer when no one is actually asking anything?