What was found
DURING CLIMB THE CREW RECEIVED A HYDRAULIC LOW MESSAGE AND THE GEAR DID NOT RETRACT. THE CREW RETURNED TO SAV FOR MAINTENANCE. AFTER T/O, HYD 3LO PRESS MSG, INBD GND SPLRS, AND L/G DISAGREE WARNING 1200-1500 SYS 3 PRESSURE. RAN QRH. AFTER 3 MIN. PRESSURE RETURNED AND GEAR RETRACTED. MX PERFORMED OPERATIONAL TEST OF THE LANDING GEAR EXTENSION / RETRACTION SYSTEM IAW CRJ 900 AMM 32-30-00-710-801-A01. OPS CHECK GOOD.