What was found
(CAN) DURING THE SCHEDULED TASK TO LEAK CHECK THE LANDING GEAR SYSTEM (LANDING GEAR MM M-8101, ROUTINE MAINTENANCE) IT WAS NOT POSSIBLE TO BUILD PRESSURE IN THE LANDING GEAR HYDRAULIC SYSTEM WITH THE MANUAL PUMP INSTALLED. UPON INVESTIGATION IT WAS FOUND THAT FLUID WAS BEING ROUTED TO THE DOWN PORT AND THE RETURN PORT AT THE SAME TIME. ELECTRICAL POWER WAS ON THE AIRCRAFT AND THE LANDING GEAR SELECTED TO THE DOWN POSITION. THIS VALVE HAD BEEN PREVIOUSLY REMOVED FROM ANOTHER SIMILAR TYPE AIRCRAFT FOR THE SAME PROBLEM AND WAS REPAIRED. REF NR ASR-6188-011605. WHEN CYCLED USING THE AIRFRAME SYSTEM HYDRAULIC PUMP THE LANDING GEAR OPERATED CORRECTLY AND APPEARED TO NOT HAVE AN FAULTS. (TC NR 20060828002)