LOST COM PROC USED BY TWIN TURBOPROP CARGO FLT INTO PHX; AZ.

Narrative

WHILE INBOUND ON THE JESSE 1 ARR INTO PHX; I EXPERIENCED LOST COMS IN IMC JUST PRIOR TO RECEIVING (EXPECTING) RADAR VECTORS TO THE ILS RWY 8 PHX. MY LAST COMPLETE COM WAS THE SECOND RESPONSE (I HAD CHKED IN WITH THE CURRENT ATIS EARLIER) FROM PHX TRACON 128.65. I WAS ASSIGNED TO 'DSND AND MAINTAIN 8000 FT AT HOMER INTXN.' WHILE INBOUND FROM BUNTR INTXN; ON A 225 DEG HDG (CHARTED); AN ACFT RPTED LIGHT RIME ICE AT MY ALT AND ATC REPEATED IT BACK TO ME. I RESPONDED THAT I WAS ALSO EXPERIENCING THE SAME CONDITIONS. I DID NOT RECEIVE A REPLY; BUT WAS NOT EXPECTING ONE NOR DID I THINK THAT IT WAS UNUSUAL. 3-5 MINS AFTER THAT XMISSION; I BEGAN TO NOTICE NO RADIO CHATTER AND WAS EXPECTING MY VECTORS TO THE APCH. I CALLED FOR A RADIO CHK AND MADE SEVERAL ATTEMPTS TO INITIATE RADIO CONTACT. THE RADIO LIGHTS WERE STILL ON; AND THE NAVS STILL WORKED. I BEGAN TO TROUBLESHOOT ALL POSSIBLE PROBS I COULD THINK OF: VOLTAGE; INVERTERS; CIRCUIT BREAKERS; RADIO MASTER; EMER RADIO SWITCH; SQUELCH; HAND-MIKE; HEADSETS; JACKS; DIFFERENT FREQS; ETC. WHEN I DECIDED THAT I WAS DEFINITELY IN A LOST COM SIT I DIALED IN 7600 ON THE XPONDER AND PROCEEDED DIRECTLY TO THE PHX VOR (AS PUBLISHED FOR LOST COM). DURING THIS TIME; I OCCASIONALLY HEARD A FEW MUFFLED RADIO XMISSIONS WHICH ADDED TO MY CONFUSION IN TRYING TO DETERMINE THE CAUSE. I HAD ALL COM/NAV VOLUMES UP AND THE SQUELCH UP. AT ONE POINT; I HAD JIGGLED THE PUSH-TO-TALK AND DID NOT NOTICE ANY DIFFERENCE IN HOW IT FELT PRIOR TO LOSING COM. I CONTINUED TO XMIT MY INTENTIONS AND MAINTAINED 8000 FT. AT THE TIME OF LOST COM; THE ATIS WAS 40 MINS OLD. THE APCH IN USE (FOR ACFT FROM THE N) WAS ILS RWY 8. I HAD IT OUT AND HAD BRIEFED IT TO MYSELF DURING CRUISE. ALTHOUGH NOT THE ONLY OPTION (VOR/DME-A); I FELT CONTINUING WITH THE ILS RWY 8 WAS THE BEST COURSE OF ACTION. THE APCH PLATE WAS ACCESSIBLE AND ALREADY BRIEFED AND I WAS EXPECTING ATC TO BE CLRING TFC FROM THAT APCH. WITH THE HIGH TASK SATURATION OF SINGLE PLT IMC WITH NO AUTOPLT; IN OCCASIONAL LIGHT CHOP; WHILE TRYING TO TROUBLESHOOT AND NAV; I DID NOT WANT TO ATTEMPT TO TRY A DIFFERENT APCH. ONCE OVER THE ARPT/VOR; I DECLARED AN EMER (IN THE BLIND) AND PROCEEDED OUTBOUND WITH THE 078 (LOC) IN NAV #1 AND 078 DEG RADIAL PHX VOR IN THE #2 NAV. I PLANNED TO DSND TO 5000 FT INSIDE ILIKE INTXN; AND IF I DIDN'T BREAK OUT (VMC); DO A COURSE REVERSAL (NON PUBLISHED/CHARTED) AND PROCEED INBOUND ON THE ILS. WHILE DSNDING THROUGH 5500 FT; I ENCOUNTERED VMC; REVERSED COURSE AND PROCEEDED INBOUND ON THE ILS. AT APPROX 8 MI FROM THE ARPT; I MADE VISUAL CONTACT WITH THE RWY. AT APPROX 4 MI; I BEGAN TO HEAR RADIO XMISSIONS AND WAS CLRED TO LAND RWY 8. PHX MAINT HAS SINCE REMOVED AND REPLACED THE DEFECTIVE MIKE/PUSH-TO-TALK ON THE PLT'S SIDE.