Emergency brake handle

in 476th vFG's checklists i found this:

LAUNCH COCKPIT SETUP

LEFT CONSOLE

23. Emergency brake handle - Push IN (if starting left engine first); pull OUT (if starting right engine first).

could someone explain why? thank you

Left and Right engines feed discrete hydraulic systems also called Left and Right. Different core systems within the jet that rely on hydraulics feed from either the left or right system. Normal brakes are fed by the Left system and so when starting the left engine the moment you have Left Hydraulic system pressure you have brakes and so you have a means to prevent your jet from running away from you if for some reason the engine powers up uncommanded or what have you.

If you start the right engine first you have no brakes so its prudent to arm the emergency brakes instead which relies on an accumulated reserve of hydraulic power sufficient for a few full presses and releases of the toe brakes.

^ All the above from pure recollection. I reserve the right to be proven incredibly wrong. :music_whistling:\

EDIT. Turns out the Right Hydraulic system supplies the Emergency Brake which is why you can use it when doing a Right Engine start before the Left. For more information check the Hydraulic Emergencies section of the doc.

Left and Right engines feed discrete hydraulic systems also called Left and Right. Different core systems within the jet that rely on hydraulics feed from either the left or right system. Normal brakes are fed by the Left system and so when starting the left engine the moment you have Left Hydraulic system pressure you have brakes and so you have a means to prevent your jet from running away from you if for some reason the engine powers up uncommanded or what have you.

 

If you start the right engine first you have no brakes so its prudent to arm the emergency brakes instead which relies on an accumulated reserve of hydraulic power sufficient for a few full presses and releases of the toe brakes.

 

^ All the above from pure recollection. I reserve the right to be proven incredibly wrong. :music_whistling:\

 

EDIT. Turns out the Right Hydraulic system supplies the Emergency Brake which is why you can use it when doing a Right Engine start before the Left. For more information check the Hydraulic Emergencies section of the doc.

just as i thought, thank you

Very insighful explanation for me too. Thanks!

Thank you from me as well!

But I wonder... aren't the chocks in place during startup anyway (in RL)?

Thank you from me as well!

But I wonder... aren't the chocks in place during startup anyway (in RL)?

Yes but stuff happens and a pilot could have a reason to use the breaks.

Thank you from me as well!

But I wonder... aren't the chocks in place during startup anyway (in RL)?

Good luck taking the chocks off, if the plane is leaning against them. :)

Good points! I understand that.