You are right Pat, this decision has to be carefully assessed...
Just a few considerations:
If you deselect the generator, you lose the hyd system or all generators, as you stated, but this if a case
if the other generator fails.
It would take a
subsequent failure, as you call them in your excellent book.
And in that case you can easily reconnect the first gen on line.
By losing a Transfer bus, you lose, depending on the wirings of the various airplanes which are unfortunately quite different, the CM1 or CM2 flight instruments; with a loss of Transfer bus 2 you will lose the right IRS after 5 minutes (!); you have to avoid icing conditions; you lose the various indications, trims and so on...
I don't know, I've always considered the Transfer bus more important than the Generator bus, but of course it depends on the day...
Let me know what you think.
Cheers, LEM
