Hi

Can someone please help as I have just purchased the 777 and love it , absolutely amazing worth every penny.

 

My question is I seem to be running the proper procedures so I think, my only issue is when I disconnect external power from fmc and overhead panel I lose complete power in vc now shouldn't the power be continues after the apu is on and external power disconnected??

 

Please help thanks!

I think u are missing something..

Battery ?, is APU online ? ( APU need some time to be online, it is not instant process, PMDG simulate it very accurate ).

U must check and confirm APU status before switching off external power.

Thank you, at what point I time should the APU be switched on?

 

I was turning it on just after setting up fmc

 

Is this somewhat correct? Or should it be turned on earlier?

I turn the APU on right before I want to pushback

You get an "APU RUNNING" EICAS message when the APU is supplying power to the aircraft. At that point it is safe to disconnect External power.

Thank you so much for the responses much appreciated. Back to flying this beautiful bird.

You also have to make sure the APU generator is on. In the 777's case the APU generator is normally on all the time as switching to APU power is automatic in the 777 when the APU is running and there are no other power sources connected. In the 737 however you would want to make sure you click the APU generator before disconnecting external power.

The APU is switched on as late as possible (before pushback and disconnecting ground power) to safe fuel.

 

That means you also need external air, and there lies the problem.

In many places of the real world those external air units really dont do all that well.

Some of them keep shutting down untill a tech restarts them, others just dont deliver enough air to cool the tube on a hot summers day, or heat it enough in winter.

 

When it is hot outside, we often turn the APU on when we start boarding because the additional heat of 300pax combined with a weak external air source is not a good combo.

 

Also many airports have regulations as to how long you are allowed to have your APU running (for noise reasons).

 

 

As pax comfort for FSX is only simulated by Heidi of A2A (as far as I know) , you can turn on the APU any time you feel like it.

As mentioned above, everything is automatic.

Just make sure all elec switches on the overhead panel are in the on/auto position.

Thank you 777simmer  for the informative answer. How long does it take for APU to run ?I ask this because after I had programmed my fmc I then switched on APU and did all my checks contact tower etc etc almost ready for pushback say a good 5 10 min shouldn't that be sufficient  time for APU to run?

Thank you 777simmer  for the informative answer. How long does it take for APU to run ?I ask this because after I had programmed my fmc I then switched on APU and did all my checks contact tower etc etc almost ready for pushback say a good 5 10 min shouldn't that be sufficient  time for APU to run?

 

It should only take 1-2 mins at the most to start the APU, its not as instant as starting a car engine

yes, 2 minutes or so.

 

If you look at the upper EICAS display, you will see a white message appear with "APU running".

On the STAT page (lower DU + DisplaySelectPanel) you can monitor the APU startup. Rising RPM should be displayed immediately after turning the APU start knob.

I have 2 follow up questions regarding the APU:

 

On landing, if I am the last flight of the night, do I need to start the APU? 

If I shut down engines at gate and APU is off, will battery power be al that is needed for lights, and open doors??

 

On cold dark start up selected in the FMC, the FMC is completely dead, how do you then select the Menu page and Ground Connection page to add external power (without using the APU).  It seems on cold dark set up, you <UST start the APU.

Regarding your first question - Do what you want! Aviation is not so rigid.  simply ask yourself 'do I require the APU?'

 

Real world ops  would normally require you to get the APU running on taxi in, even if it is the last flight of the day.  Why would you think it would be different to any other flight of the day?

Well if you are going to turn the plane around in 30 minutes, you probably need to maintain power to get the plane set up for the next flight, keep the FMC alive, the  AC running etc.

 

If you know it is the last flight of the night and you are going to do a full shutdown, why start the APU.

But I am not sure if it matters.