AN MD80 ON 3 MI FINAL AT 1000 FT HAD NOSE LNDG GEAR FAIL TO EXTEND. EXTENDED ON GAR BUT INCURRED LOSS OF R HYD SYS. CAUSE UNKNOWN.

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ON FINAL FOR RWY 4R AT ORD; FO WAS FLYING; AND ASKED FOR GEAR DOWN. I LOWERED THE HANDLE; BUT THE GEAR DID NOT COME DOWN. I CHKED HYD SWITCHES IN THE ON HIGH/HIGH/ON. AFTER A FEW SECONDS; THE MAIN GEAR BOTH CAME DOWN 'GREEN' BUT THE NOSE GEAR STILL INDICATED UNSAFE. R HYD QUANTITY WAS NEAR ZERO; BUT PRESSURE WAS NEAR NORMAL THOUGH IT WAS UNSTEADY. WITH NO SAFE NOSE GEAR INDICATION WE WENT AROUND. DURING THE GAR; THE NOSE GEAR CAME DOWN AND INDICATED SAFE. WE LEFT THE GEAR DOWN. THE R HYD QUANTITY WAS STILL NEAR ZERO; BUT THE PRESSURE WAS NOW STABLE AND NORMAL. THE L SYS OPERATED NORMALLY THROUGHOUT. WE LANDED NORMALLY. SINCE OUR GATE WAS OCCUPIED; GND SENT US TO RWY 32R PAD. AS SOON AS I PARKED THE BRAKES; AN EMPLOYEE IN THE BACK SAID HE HEARD A GRINDING SOUND NEAR THE R ENG. I DECIDED TO TURN OFF THE HYDS TO THE R SYS. I THEN REQUESTED THAT MAINT COME OUT AND PIN THE GEAR WITH NO PRESSURE ON THE GEAR. WE THEN TAXIED IN NORMALLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE EXACT COMPONENT THAT CAUSED THE LOSS OF FLUID AND PRESSURE IS UNKNOWN. THE RPTR SAID MAINT HAS NOT ADVISED THE CREW OF THE MAINT ACTION TAKEN.