Markoz,

I've experienced this problem with both the 727 and C-130. In my experience the key difference is that while you'll never lose electric power if you sit in one place in the tarmac, as soon as the plane starts moving on the ground the countdown to power loss starts (in the case of a long taxi you can lose power before getting to the runway). Hitting ctl-E works with the C-130--maybe try that with the 727 as well?

This is a pretty serious problem and it's a shame that CS seems not to know how to fix it.  :(