The big question: before Battery power is applied, or an extended lengthy period since Battery was on and Accumulator was pressurized - how effective is the Parking Brake? The jet was towed into position, you set the parking brake ... departure is imminent ... do you need chocks?
In the II/V/Ultra, the brakes use the accumulator to increase effectiveness, but they will work by simply pumping the pedals using the master cylinders. In the Encore, the brake system uses a metering valve that relies on normal DC electrical power to operate, therefore the parking brake cannot be set without electrical power.
Thank you for pointing out the difference with the Encore system. I can't help thinking, if the Encore pedals give some resistance, even though the Accumulator isn't charged or hasn't been charged recently, there would still be enough pressure on the brake pads to hold the jet from rolling (no chocks) shortly before departure. Dealing with one or more chock blocks right before entering the jet to depart seems like a potential distraction.
So, the pump restores pressure to the brake fluid. The nitrogen charge always exists, or should exist, as indicated by the Pre-Charge level on the needle.
