AN MD88 FO RPT ON AN ALT BUST WITH DFW APCH CTLR WHILE DSNDING OUT OF 16000 FT; WITH LOSS OF COM AND ASSOCIATED ACFT AUTOPLT PROBS ON THE JUMBO ARR; DFW; TX.

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THIS IS AN EXAMPLE OF HOW A FEW SEEMINGLY INSIGNIFICANT PROBS; WHEN ADDED TOGETHER; CAN LEAD TO A POTENTIALLY SIGNIFICANT PROB. I AND MY FO LEFT PBI AT PM45Z ON DEC/SAT/99. WE LEFT WITH THE FOLLOWING PROBS: 1) THE AIRPLANE HAD A HISTORY OF AUTOPLT DISCONNECTS DUE TO 'ELEVATOR FEEL FAULT' AND 'ACU EXCITATION' MESSAGES. 2) IT WAS A DARK NIGHT; VERY LITTLE MOONLIGHT AND THERE WERE RAIN SHOWERS AND TSTMS AT THE DEST ARPT; DFW. 3) THERE WERE SIGNIFICANT WINDS AT ALT. 4) MY FO'S MIKE WAS STOWED ON TOP OF; RATHER THAN IN; THE WIRE CAGE DESIGNED TO HOLD IT. WE WERE CLRED DIRECT TO KNEAD AND THE JUMBO 2. IT TOOK US A MOMENT TO FIND THE ARR IN OUR BOOKS AND WE TURNED R TO KNEAD. ZFW THEN CLRED US TO CROSS KNEAD AT 11000 FT. (THE MANDATORY XING SPD AT KNEAD IS 250 KTS.) WE WERE 30 MI FROM KNEAD AND HAD A 100 KT TAILWIND. FO BRIEFED AN ILS TO RWY 36L. PASSING 16000 FT AT OUR MAX DSCNT RATE WITH SPD BRAKES AND WITH A 60 KT TAILWIND; WE REALIZED WE WOULD NOT MAKE OUR XING RESTR. AT THAT POINT CTR SENT US OVER TO APCH CTL ON 133.62. I ACKNOWLEDGED AND SWITCHED FREQS. I GOT NO ANSWER WHEN I CHKED IN WITH APCH CTL. AFTER SEVERAL ATTEMPTS I RETURNED TO CTR FOR ANOTHER FREQ AND STILL NO ANSWER. AFTER CHKING ALL OF MY RADIO BUTTONS AND SWITCHES AND ASKING MY FO TO DO THE SAME; I TRIED SEVERAL OTHER FREQS FROM MY DFW APCH PLATES; STILL NO ANSWER. I THEN ATTEMPTED RADIO #2. IN THE MEANTIME; AS WE APCHED 11000 FT ON A DARK NIGHT IN THE WX AND SURROUNDED BY RAIN SHOWERS; THE 'ELEVATOR FEEL FAULT' MESSAGE CAME ON AND THE AUTOPLT DISCONNECTED. THE 'ACU EXCITATION' MESSAGE ALSO CAME ON AND OFF REPEATEDLY CAUSING THE MASTER CAUTION LIGHT TO COME ON REPEATEDLY. (IN THE DARK THE MASTER CAUTION LIGHT IS VERY BRIGHT.) MY FO DID A GREAT JOB OF HAND FLYING THE AIRPLANE THROUGH THE ARR AND TOWARD TTT IN THE EVENT WE HAD TO DO A RADIO OUT DSCNT AND APCH; CONSIDERING THE FLURRY OF ACTIVITY IN THE COCKPIT. FLYING INBOUND TO TTT; I PUT 7600 IN OUR XPONDER BUT CONTINUED TO SEARCH FOR A USABLE FREQ. I HEARD SOME FEEDBACK FROM MY FO'S MIKE AND AGAIN ASKED HIM TO CHK HIS RADIO SETTING BECAUSE I THOUGHT WE MIGHT HAVE A STUCK MIKE BUTTON. FINALLY; 12 MI FROM TTT AT 11000 FT AND 250 KTS; I MADE CONTACT WITH APCH CTL ON #2 RADIO ON FREQ 118.1. APCH VECTORED US TO A DOWNWIND AND ON FOR AN ILS APCH TO RWY 35C. WE BRIEFED THE NEW APCH AND FINISHED ALL CHKLISTS. APCH ATTEMPTED 1 FREQ CHANGE BUT WHEN IT WAS UNSUCCESSFUL; WE RETURNED AND HE CLRED US FOR THE APCH AND CLRED US TO LAND. WE BROKE OUT OF THE WX AT ABOUT 600 FT. THE MASTER CAUTION LIGHT CONTINUED TO COME ON EVERY 3-5 SECONDS THROUGHOUT THE ENTIRE EVENT. ON LNDG; MY FO MADE RADIO CALLS BY SWITCHING FROM INTERCOM TO RADIO #2. AFTER ARR AT THE GATE WE FOUND MY FO'S MIKE WEDGED BTWN THE WIRE CAGE AND THE COCKPIT WALL WITH THE XMIT BUTTON DEPRESSED. IN RETROSPECT; WE DISCOVERED THAT WHATEVER RADIO MY FO HAD SELECTED ON HIS RADIO INTERCOM PANEL WAS BLOCKED. TRYING THE SAME FREQ ON ANOTHER RADIO DIDN'T WORK BECAUSE THE FREQ WAS BLOCKED. THAT; COMBINED WITH THE FACT THAT NOT ALL APCH FREQS WERE BEING USED INITIALLY; GAVE US THE IMPRESSION THAT OUR RADIOS WERE OUT. THE FACT THAT WE WERE ON AN ARR; BEING RUSHED BY TAILWINDS; WITH A LATE RTE CHANGE AND DSCNT CLRNC; IN THE DARK; IN THE WX; WITH THE AUTOPLT OFF AND THE MASTER CAUTION FLASHING; MADE IT DIFFICULT TO TROUBLESHOOT OUR RADIO PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE FO STATED THAT HE NORMALLY USES THE HEADSET MIKE AND HIS YOKE RADIO SWITCH. THIS IS WHILE HE IS CLBING; DSNDING. IN CRUISE HE USED THE HANDHELD MIKE AND HAD NOT REALIZED HE HAD PLACED IT INTO AN INCORRECT POS JUST PRIOR TO 16000 FT.