AN ACR CREW DIVERTS TO AN ALTERNATE ARPT WITH MIN FUEL WHEN BOTH ILS AND VOR INDICATIONS PRECLUDE A COMPLETED APCH IN WX. MAINT FOUND WATER IN THE RECEIVERS ANTENNA.

Narrative

DEPARTED BOS AS A REGULARLY SCHEDULED PAX FLT BOUND FOR RIC WITH 8000 LBS FUEL; INCLUDING 1800 LBS FOR 45 MIN RESERVE. NO ALTERNATE WAS REQUIRED; NOR WAS ALTERNATE FUEL CARRIED; EVERYTHING PROCEEDED NORMALLY UNTIL AUTOPLT ATTEMPTED TO INTERCEPT 16 LOC. (FMS NAVIGATION HAD BEEN USED TO THIS POINT.) LOC NEEDLE MOVED RANDOMLY FROM STOP TO STOP. DISCONNECTED AUTOPLT AND CONTINUED UNTIL LOWEST ALTITUDE APPROVED BY ATC. LOC NEEDLE WAS STILL ERRATIC; SO WE EXECUTED A MISSED APCH. (ATC AND OTHER ACFT RPTED NO PROBS WITH THE LOC. ALSO; HAD GOOD LOC ID.) DECIDED TO TRY VOR 16 SINCE LOC WAS INOP. VECTORED ONTO VOR; AND NEEDLES AGAIN MOVED ERRATICALLY FROM STOP TO STOP. (BOTH #1 AND #2 NAV RADIOS WERE AFFECTED). FLEW APCH USING FMS INSTEAD; (NOT AN APPROVED PROC; BUT FUEL WAS GETTING LOW); BUT WX HAD DROPPED BELOW VOR MINS. ON MISSED APCH; RIGHT FUEL GAUGE ENTERED YELLOW RANGE. DECLARED MIN FUEL AND DIVERTED TO ORF; WHERE WX WAS 2600 AND 10 MILES. ENROUTE; WE SPOKE WITH MAINT AND REQUESTED ASSISTANCE. THEY SAID THIS PROB HAD BEEN RPTED EARLIER; BUT THEY COULD NOT DUPLICATE IT. REALIZED WE WOULD LAND WITH 1300 LBS FUEL AND DECLARED EMER. (35 MINS FOB) LANDED UNEVENTFULLY AT ORF. MAINT REMOVED CHAFE TAPE AND WATER FROM ANTENNAS; WHICH FIXED PROB. THEY STATED THIS WAS RECURRING PROB IN THE EMB-145. LOSS OF ALL VOR AND ILS NAVIGATION IS A SERIOUS EMER. MAINT DIDN'T SEEM TO REALIZE THAT WE COULD HAVE CRASHED IF WX AT ORF HADN'T BEEN VFR. THIS IS A DANGER TO FLT SAFETY THAT MUST BE ADDRESSED PROMPTLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: IT WAS REVEALED IN CALLBACK THAT THE CREW WHO FLEW THIS ACFT PREVIOUSLY HAD A SIMILAR FAILURE INDICATION; BUT ASSUMED IT WAS GND INTERFERENCE WITH THE RADIO SIGNAL. IT WAS ALSO RPTED IN DISCUSSIONS WITH MAINT IT WAS FOUND THAT THIS HAD OCCURRED ON OTHER ACFT OF THIS TYPE AT DIFFERENT LOCATIONS. THE ACFT HAD BEEN OPERATED MOST OF THE DAY IN WX CONDITIONS THAT INCLUDED RAIN. THE CHAFE TAPE IS APPARENTLY USED TO PREVENT WEAR ON THE LEADING EDGE OF THE ANTENNA. THE LOCATION OF THE ANTENNA ON THE ACFT WAS NOT KNOWN BY THE RPTR. THERE WAS NO PROB WITH THE GLIDE SLOPE INDICATION.