Moving the flaps for prefight . . . don't.

The Issue

Since you normally park the airplane with the flaps up to protect all the mechanisms forward of the flaps, you will need to extend the flaps for preflight. But in any G-V series airplane, the flaps and stabilizer are connected electronically. The flaps require hydraulic pressure and DC electrical power. The stabilizer requires AC electrical power. If you move one without the other, computers become upset.

The preflight procedure to extend the flaps on battery power comes from the G-V:

This works great in a G-V so they put it in the G-450, which has a flap system that is almost identical:

When we took delivery, this method worked about half the time. We complained that the system wasn't identical, the G-450 has that pesky ALT FLAP switch. So the preflight procedure was changed to:

That never worked.

Solution

If you make the mistake of using any of these procedures in a G-450, you can try pulling and resetting the three flap control circuit breakers:

FLAP / STAB PRI L DC: POP, C-6
FLAP / STAB PRI R RC: CPOP, C-6
FLAP / STAB SEC DC: POP, E-1

That doesn't always work, sometimes you need to do a full power shutdown and restart.

Having learned your lesson, you should do what most G-450 crews do: wait until you have AC power before moving the flaps.