C525 first officer reported brake system failure after engine start before taxi.

Attributes
ACN	1633213
Time
Date	201904
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Citationjet (C525/C526) - CJ I / II / III / IV
Flight Phase	Taxi
Component
Aircraft Component	Normal Brake System
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Critical Ground Event / Encounter Other / Unknown

Narrative:

We did our before start checklist and started the engines. Once the engines were started and the chocks were removed the parking brake was released and the airplane started to roll. I looked down at the captain's feet and he pressed the brakes and the airplane continued to roll I then immediately pressed my brakes and the airplane didn't stop. The captain then turned the engines off and pulled the emergency brake until the airplane came to a complete stop. The airplane was the chocked and secured. Really there was nothing we could've done. Good thing is it was caught before anything major could've occurred.

Original NASA ASRS Text

Title: C525 First Officer reported brake system failure after engine start before taxi.

Narrative: We did our before start checklist and started the engines. Once the engines were started and the chocks were removed the parking brake was released and the airplane started to roll. I looked down at the Captain's feet and he pressed the brakes and the airplane continued to roll I then immediately pressed my brakes and the airplane didn't stop. The Captain then turned the engines off and pulled the emergency brake until the airplane came to a complete stop. The airplane was the chocked and secured. Really there was nothing we could've done. Good thing is it was caught before anything major could've occurred.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.