SAAB 340 FLC MADE GAR IN ORDER TO TROUBLESHOOT AN ABNORMAL LNDG GEAR EXTENSION PROB. SUBSEQUENTLY; PROB WAS RESOLVED AFTER CORRECT PROCS WERE USED PER ACFT OPERATING MANUAL.

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I WAS THE PNF. ON THE ILS RWY 4R APCH IN BOS; CAPT CALLED FOR GEAR DOWN. WE HAD A MASTER CAUTION ALERT. I CHKED THE CENTRAL WARNING PANEL STATED HYD LIGHT ON AND CANCELED THE ALERT. THE GEAR IN-TRANSIT AND NOSE GEAR LIGHTS WERE ON; BUT THE MAIN GEAR LIGHTS WERE NOT. I COULD SEE THAT THE MAIN ACCELERATOR PRESSURE INDICATED ZERO. CAPT INSTRUCTED ME TO CONTACT TWR AND TELL THEM WE WERE GOING AROUND DUE TO AN ABNORMAL INDICATION. CAPT STATED HE WOULD CONTINUE TO FLY AND TALK ON THE RADIO WHILE I WORKED THE CHKLIST. CAPT HANDED ME THE EPC AND I READ THE HYD LIGHT ON PROC OUT LOUD FROM THE EPC READING THE FIRST ITEM I NOTED THE CAPT HAD INITIALLY TURNED THE HYD PUMP TO OFF. I READ THE SECOND ITEM EMER AND MAIN ACCELERATOR PRESSURE CHK (IF EMER AND MAIN ACCELERATOR PRESSURE BOTH LOW; BELOW 2000 PSI). I LOOKED AT THE HYD PANEL AND COULD SEE THE MAIN ACCELERATOR INDICATED ZERO. THE CAPT CONCURRED AND I CONTINUED THE CHKLIST. AIRSPD WAS ALREADY BELOW 200 KIAS AND WE DID NOT CHANGE FLAP POS. LNDG GEAR HANDLE WAS DOWN. THE EMER LNDG HANDLE WAS PULLED. WE THEN HAD SAFE GEAR INDICATIONS. CAPT INSTRUCTED ME TO MAKE A PA AND CONTACT BOS OP AND ADVISE THEM OF OUR SIT. WHILE BEING VECTORED FOR A SECOND APCH CAPT CALLED FOR THE HYD CHKLIST IN AOM VOL 1. AS I READ THE PROC ALOUD WE NOTED THE EMER ACCELERATOR INDICATED NORMAL APPROX 3000 PSI. I CONTINUED TO READ PROC FOR LOW MAIN AND NORMAL EMER ACCELERATOR PRESSURE. THE CHKLIST CALLED FOR HYD CIRCUIT BREAKERS TO BE RESET. CAPT RESET THE SPECIFIED CIRCUIT BREAKER AND WE REGAINED FUNCTION OF THE HYD PUMP. AT THAT POINT WE HAD NORMAL INDICATIONS AND WERE ABLE TO CANCEL EMER.