Cessna has an electrical load shed function that disables the interior electrical equipment in flight and external drain heaters if both generators are not operating.
An important maintenance item to remember, when the generators are not on line with the aircraft on jacks for maintenance, the load shed function will be activated and the interior electrical equipment will be inoperative. This includes interior and exterior items such as the interior lights, galley equipment, AC outlets, and the drain heaters.Squat switch simulator boxes will need to be installed to operate the interior electrical equipment.
The Environmental printed circuit board (PCB) NZ126, P/N 6318358-20 causes the load shed function to activate when the aircraft is on jacks. This is because the PCB recognizes the aircraft being in the air mode and the generators are not operating.
The 6318358-20 PCB is installed on 525 aircraft units 525-0680, -0685 thru -0701, 525A aircraft units 525A-0417, -0439 and On, and 525B aircraft units 525B-0263, -0294 and On.