ATR prop brake can be activated without hydraulic power

[lynx33635]

I have to retrieve the source info, however I’ve read the running Engine #1 allow hydraulic pressure to be used for Prop brake

At least here, however I have to retrieve my initial read :

ATR prop brake will not disengage once Engine #2 started (only 72-600 the 42-600 is OK)

You could start engine one, shut down 2, turn off the Aux hyd pump and brake switch. Then start 2 again. It’s a possible solution. But I don’t think you need to shut down #2. For this to work you need enough pressure in the hydraulic system. So you need to: Start engine #1, this engine will provide pressure to the system. As correctly stated by lolz3346630: Be sure that you disengage the prop brake while condition lever #2 is on the feather position otherwise the prop break cannot…

[EDIT] Found !!!

ATR - Auxiliary Hydraulic pump operating when engine 1 is started first

Not a joke … [auto mode hyd blue]