What was found
(CAN) UPON APPROACH GEAR DOWN POSITION WAS SELECTED AND THE POWERPACK FAILED TO OPERATE THE MAIN GEAR EXTENDED FULLY AS DESIGNED AND THE NOSE GEAR FAILED TO GIVE A GREEN DOWN AND LOCKED POSITION INDICATION. THE APPROACH WAS ABORTED AND A GO AROUND WAS CARRIED OUT. THE MANUAL GEAR EXTENSION PUMP WAS USED TO EXTEND THE NOSE GEAR WITH SUCCESS. INSPECTION REVEALED THE POWER PACK RELAY HAD FAILED TO MAKE CONTACT DUE TO EROSION OF THE CONTACTS. A NEW UNIT WAS INSTALLED AND FUNCTION TESTED.