DHC6-300 FLT CREW HAS LOW OIL PRESSURE WARNING; SECURES THE ENG; DECLARES AN EMER AND DIVERTS TO ZZZ.

Narrative

WHILE ENRTE FROM ZZZ TO ARPT ZZZ1; THE R ENG OIL PRESSURE WAS OBSERVED THROUGH 45 PSI (NORMAL RANGE 80-100 PSI). AFTER CONTACTING FLT DISPATCH; WE WERE TOLD TO RETURN BACK TO BASE. MAINT ALSO TOLD US TO REDUCE PWR; WHICH WE HAD ALREADY DONE. THE R OIL PRESSURE LIGHT BEGAN TO FLICKER SHORTLY THEREAFTER. IMMEDIATELY; WE BEGAN TO CONSULT THE CAUTION LIGHT CHKLIST. HAVING THE LOW OIL PRESSURE INDICATION ON THE GAUGE AND THE CAUTION LIGHT ILLUMINATE SIMULTANEOUSLY IS AN AUTOMATIC ENG SHUTDOWN. WE PROCEEDED TO CONSULT THE CAUTION CHKLIST; WHICH THEN REFERRED US TO THE EMER CHKLIST; ENG SHUTDOWN PROC. THE R ENG WAS IMMEDIATELY FEATHERED AND SHUT DOWN TO PREVENT ENG DAMAGE. OIL WAS OBSERVED ALL OVER THE R SIDE OF THE FUSELAGE. AFTER SECURING THE R ENG; WE CONTACTED ZZZ APCH. WE WERE 'RADAR CONTACT' 26 DME FROM THE ZZZ VOR. WE THEN PROCEEDED TO DECLARE THE EMER. ALT WAS AT OUR DISCRETION. THE AIRPLANE WAS PERFORMING WELL; FLYING AT 120 KIAS AND MAINTAINING 6100 FT MSL WITH NO PROBS. APCH THEN ASKED US FOR THE AMOUNT OF FUEL ON BOARD AND NUMBER OF SOULS. WE HAD 1000 LBS OF FUEL ON BOARD WITH 11 SOULS. APCH CTL THEN ASKED US WHICH ARPT WE WISHED TO LAND AT. WE; THE CREW; DECIDED ON LNDG IN ZZZ; OUR HOME BASE. WE DECIDED TO PROCEED TO ZZZ BECAUSE IN OUR DETERMINATION; SHUTTING DOWN THE ENG WAS NOT DUE TO CATASTROPHIC FAILURE OR FIRE. IT WAS DUE TO LOSS OF OIL PRESSURE. WHILE ENRTE TO ZZZ; IF THE ENG SHUTDOWN BECAME A DIRE SITUATION AND REQUIRED AN IMMEDIATE LNDG; ZZZ1 WAS JUST OFF THE L SIDE OF THE ACFT. WE WERE ABLE TO MAINTAIN OUR ALT THE ENTIRE TIME UNTIL WE NEEDED TO DSND FOR LNDG. ALSO; HAD WE LANDED A ZZZ1; WE PROBABLY WOULD NOT HAVE HAD STAIRS FOR OUR PAX AND CUSTOMER SVC TO ASSIST THEM. ALTHOUGH ZZZ2 ARPT WAS CLOSEST; WE FELT AS THOUGH IT WAS NOT THE SAFEST ALTERNATIVE BECAUSE IT IS NON-TWRED AND IT HAS RISING TERRAIN SURROUNDING THE ARPT. WE ENTERED THE VALLEY ON THE ARR RTE OF FLT MAINTAINING 6100 FT MSL. WE HAD PLENTY OF ALT. IT HAS BEEN DETERMINED THAT WE ONLY FLEW 4 ADDITIONAL MI TO LAND AT OUR HOME BASE ARPT; ZZZ. ALTHOUGH ZZZ1 HAS EMER EQUIP ON THE FIELD; ZZZ HAD ENOUGH RESPONSE TIME AVAILABLE (THE TIME IT TOOK US TO FLY 26 MI SINGLE ENG); SO WE FELT THIS WAS JUST AS SAFE OF AN ALTERNATIVE AS IT WOULD HAVE BEEN TO LAND AT ZZZ1. AFTER WE HAD SUCCESSFULLY LANDED AT ZZZ; THE CTL TWR ASKED US IF WE REQUIRED ASSISTANCE; AND WE REPLIED 'NEGATIVE.'