As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HYD 1 LOW PRESS WARNING FOLLOWED BY HYD EDP 1A WARNING OPERATED ENGINE 1. 11 WITH THE FAILED PUMP. PUMP CAVATED A LOUD NOISE AND VIBRATION AFTER T/O. AIRCRAFT RETURNED TO ATL AFTER T/O. EMERGENCY DECLARED. FLT 4596 DEL 126 MINS REMOVED AND REPLACED NR 1 HYD EDP IAW CRJ200AMM29-11-00. OPS CHECK GOOD, [SDR CLOSED]