“Day three,” announced Stan, the lead instructor, a man whose beard had more gray than an old 737’s wiring bundle. “You’ve learned where the batteries live. You’ve traced the bus tie breakers. Today, you learn the truth.”
“Time to APU start?” Stan asked.
“Isolate the failed generator,” she read aloud. “Pull the GEN 1 drive disconnect. Then shed non-essential loads from Bus 1—cargo heaters, galley, passenger entertainment.” Boeing 737 Electrical System Maintenance Training Manual