Kiskaloo
It occurred to me a while ago that perhaps too much was being asked of the APU/MAIN Batt system, as designed. It turns out there is a similar system one rack above the main problem. So it would be of great interest to see how Boeing addresses the AD. There are myriad problems, most of which seem to be a result of "utilizing" the Larger groups almost casually, as if they represent a time proven system, rather than what we see, a very problematic new-ish iteration of a Battery that got its credentials from the industry after the Dreamliner launched.
I am stuck on how building a bigger box solves the reliability problems. Unless the swelling, misaligned rolls, and internal shorting are remedied, the result will be safe but inert "back-ups", going off line at a rate too high to satisfy dependability. At great expense. Cannot a windmilling donk fire up the APU?
Thank you for a great response....