GLF4 CREW INBOUND TO MHR DURING EARLY MORNING HR UNABLE TO ESTABLISH COM WITH TWR AND LANDED USING CTAF PROC.

Narrative

THIS WAS A LATE NIGHT FLT FROM BANGOR; ME (BGR) TO SACRAMENTO MATHER FIELD (MHR) FOR A PAX DROP OFF; AND CONTINUING TO SAN FRANCISCO. WE WERE CLRED FOR ILS RWY 22L APCH; AND WERE ON A LONG STRAIGHT IN FINAL. THE WX WAS CLR WITH UNLIMITED VISIBILITY. THE TIME WAS APPROX XA10 LCL. WHEN NORCAL APCH INSTRUCTED US TO CONTACT MATHER TWR; WE GOT NO RESPONSE; AND SWITCHED BACK TO APCH CTL TO CONFIRM THE FREQ. ON SECOND ATTEMPT; STILL NO CONTACT ON TWR NOR GND CTL FREQ. WE BROADCAST OUR POS AND INTENTIONS ON TWR FREQ; AND A HELI THAT WAS IN THE LCL AREA TOLD US HE HAD US IN SIGHT; AND WOULD STAY CLR OF FINAL. HE ADDED THAT HE HAD BEEN TRYING UNSUCCESSFULLY TO CONTACT TWR FOR THE LAST 10 MINS OR LONGER. WE RPTED THIS TO NORCAL APCH; WHO THEN ATTEMPTED TO CONTACT TWR ON THE LAND LINE; BUT GOT NO ANSWER TO THEIR CALL. WE CONTINUED THE FINAL APCH AND LNDG USING THE APPROPRIATE CALLS AND PROCS FOR THE TWR BEING 'CLOSED.' AFTER CLRING THE RWY; WE HEARD THE TWR TALKING TO THE HELI. HE MADE CONTACT; AND GOT TAXI CLRNC TO THE FBO. WHEN WE ASKED THE TWR CTLR IF HE HAD HEARD OUR CALLS ON FINAL; HE TERSELY REPLIED 'ROGER.' IT SEEMED HE DEFINITELY DID NOT WANT TO DISCUSS IT; AND WE DID NOT PRESS HIM FOR FURTHER DETAILS. AFTER DISCHARGING OUR PAX; WE OBTAINED OUR IFR CLRNC FROM THE SAME CTLR AND DEPARTED AT XA52 LCL FOR SAN FRANCISCO. THE ENTIRE SIT MADE ME WONDER ABOUT THE TWR CTLR'S PERFORMANCE; BUT WITH RADIO CONTACT WITH THE HELI; THE ONLY OTHER LCL TFC; THERE WAS NEVER ANY DOUBT REGARDING SAFETY. WHEN WE WERE UNABLE TO CONTACT TWR; EITHER ON THE RADIO; OR THROUGH APCH CTL'S ATTEMPTED PHONE CALL; I CONSIDERED THE TWR TEMPORARILY CLOSED AND USED APPROPRIATE PROCS.