EMB145 FLT CREW REPORTS NAV AND COMM RADIO FAILURES DURING VECTORS FOR APPROACH.

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I WAS THE PNF. THE FLT WAS NORMAL UP UNTIL WE BEGAN GETTING VECTORS FOR APCH. APCH SWITCHED US AND THE NEW CTLR GAVE US A DSCNT FROM 8000 FT TO 7000 FT; A SPD OF 210 KTS; AND AN ASSIGNED HDG. I WAS TUNING IN THE ILS RWY 24L FREQS IN TO BOTH RMU'S; BUT THERE WERE DASHED LINES WHERE THE FREQS SHOULD BE. THE FO (PF) HAD A RED 'X' ON HIS NAV AND NO GS INDICATION. I ATTEMPTED MULTIPLE TIMES TO TUNE IN THE FREQS AND CORRECT THE PROB. AT ABOUT THAT TIME WE BOTH NOTICED THAT THE RADIOS WERE QUIET AND THE FO STATED THAT WE HAD GONE THROUGH THE LOC COURSE DEPICTED ON THE MFD FROM THE FMS. I ASKED ATC IF WE WERE SUPPOSED TO INTERCEPT WITH NO RESPONSE. AT THAT TIME WE REALIZED THAT WE HAD LOST COM ALSO. I EVENTUALLY PRESSED THE TEST BUTTON ON THE RMU'S AND THE FREQS CAME BACK. WE CONTACTED ATC AND THEY INFORMED US THAT THEY HAD BEEN TRYING TO REACH US FOR 15 MI AND GAVE US VECTORS BACK AROUND TO INTERCEPT. I INFORMED THEM THAT WE HAD HAD A RADIO PROB BUT IT WAS FIXED NOW. FROM THAT POINT ON; THE FLT WAS NORMAL. UPON ARR AT THE GATE WHILE I WAS GETTING PAPERWORK; MAINT CAME TO THE PLANE FOR A SVC CHK AND THE FO QUESTIONED ABOUT THE PROB WE HAD. MAINT SAID THAT THEY WOULD RE-RACK THE NAV AND COM. I FEEL THAT MAYBE THERE SHOULD BE A PROC IN THE QRH ABOUT THIS DUE TO THE FACT THAT THE FO SAID HAD THIS PROB BEFORE. SUPPLEMENTAL INFO FROM ACN 789793: I HAVE HAD THIS PROB ONCE BEFORE IN AN EMB145. THE LAST TIME IT HAPPENED; ONLY THE NAV RADIOS WERE AFFECTED; AND WE NEVER WERE ABLE TO RETURN THEM TO NORMAL OP. WE WERE FORCED TO MAKE A VISUAL APCH IN MARGINAL VFR CONDITIONS. I BELIEVE THIS IS AN EXTREME SAFETY HAZARD. THERE EXISTS NO TRAINING OR QRH PROC FOR THIS SITUATION. I HAVE SPOKEN TO OTHER PLTS; AND THEY TOO HAVE SEEN DASHES REPLACE FREQS ON THE RMU. NOBODY; EVEN MAINT COULD OFFER A CONFIDENT EXPLANATION OR FIX. I EVEN BROUGHT THE ISSUE UP IN MY LAST RECURRENT GROUND AND THE INSTRUCTOR HAD NO INPUT.