What was found
(CAN)WHILE COMPLETING EMERGENCY GEAR SWINGS DURING MAINTENANCE, GEAR DOWN SYSTEM PRESSURIZED, OPENING THE MANUAL NITROGEN VALVE IN COCKPIT, PRESSURE DID NOT HOLD. THE BLEED VALVE WAS REMOVED AND FOUND TO BE CONTAMINATED WITH WATER AND FOREIGN MATERIAL. THE BLEED VALVE WAS CLEANED AND INSTALLED AND THE SYSTEM CHECKET OUT FINE.