When both engine bleeds closed, why can't we use the APU?
That is what I am interested in as well.
On a different note, looking at this closely as we have it seems likely that there will be a rather terrified call from the cabin informing you of smoke in the cabin and a burning smell etc. This is to be expected until the reference items of the engine fire checklist have been completed past the point where the pack is turned off on the side with the burning engine. That call from the cabin will add stress and urgency to the pilots as they proceed with securing the engine. That is common sense stuff but I imagine it would be easy to forget that it will most likely happen if your simulator training is anything like mine has been. When we get engine fires in the sim our shutdown procedures are never interrupted by the check Captain pretending to be cabin crew saying " there's smoke and a burning smell in the cabin!" , yet I imagine it's very likely if the fire is in the right place.
The biggest learning point for me from this thread is that I will be expecting that and will respond with " that's understood, call me back in two minutes if the smoke hasn't started dissipating" or something like that, and I won't be tooooo worried about it as I will expect it to dissipate as soon as the pack is switched off.
Again, I know that's common sense stuff but an increased expectancy of it will help the pilots maintain a feeling of ' no problem....that's what I expected' and continue in a controlled manner rather than start worrying that the fire is going to incapacitate the pax.
Edit: Cosmo makes a good point about this post directly below, don't let me lead you astray.