What was found
(CAN) DURING MAINT, INSPECTORS FOUND ALT GEAR EXTENSION NOT WORKING. CARRIED OUT GEAR CHECKS & DOING ALT RELEASE, ALL FAILED. HAND PUMP WAS NOT BUILDING UP PRESSURE TO LOCK MLG'S. THEY REPLACED SELECTOR VALVE WITH A PRE MOD SUM 4D013414. SELECTOR VALVE DUE TO NO STOCK OF POST MOD VALVE. DIDN'T RECTIFY THE PROBLEM, STILL NO HANDPUMP PRESSURE: CHANGED HANDPUMP & THAT SOLVED PROBLEM. THE FOLLOWING OP TEST OF ALT LDG GEAR EXTENSION HYDRAULIC SYS WAS CARRIED OUT SUCCESSFUL. SINCE FLUID FOUND HEAVILY CONTAMINATED, EMERG SYS HAS BEEN BLEED & REFILLED.