Narrative:

This is an example of how a few seemingly insignificant problems, when added together, can lead to a potentially significant problem. The airplane had a history of autoplt disconnects due to 'elevator feel fault' and 'acu excitation' messages. It was a dark night, very little moonlight and there were rain showers and thunderstorms at the destination airport, dfw. There were significant winds at altitude. We were 30 mi from knead intersection and had a 100 KT tailwind. First officer briefed an ILS to runway 36L. Passing 16000 ft at our maximum descent rate with speed brakes and with a 60 KT tail wind, we realized we would not make our crossing restriction. At that point center sent us over to approach control on 133.62. I acknowledged and switched frequencys. I got no answer when I checked in with approach control. After several attempts I returned to center for another frequency and still no answer. After checking all of my radio buttons and switches and asking my first officer to do the same, I tried several other frequencys from my dfw approach plates, still no answer. I then attempted radio two. In the mean time, as we approached 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 first officer did a great job of hand flying the airplane through the arrival and toward TTT. Flying inbound to TTT, I put 7600 in our transponder but continued to search for a usable frequency. I made contact with approach control on radio 2 on frequency 118.1. Approach vectored us to a downwind and on for an ILS approach to runway 35C. We briefed the new approach and finished all checklists. Approach attempted one frequency change but when it was unsuccessful, we returned and he cleared us for the approach and cleared 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. The fact that we were on an arrival, being rushed by tail winds, with a late route change and descent clearance, in the dark, in the WX, with the autoplt off and the master caution flashing, made it difficult to troubleshoot our radio problem. Callback conversation with reporter revealed the following information: first officer did not know which generator was associated with the excitation light. He was not aware of what the maintenance sign off was for the aircraft faults, ie, autoplt disconnects, master caution light, excitation lights, elevator feel fault. He was also unaware as to whether there was a jack screw inspection as required under the latest NTSB/FAA ruling and if so, what were the results? When asked: was the operation of the main trim motor normal, any circuit breakers found tripped and was the 'excitation light' a generator power problem or an autoplt malfunction, he was not able to answer those questions.

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Original NASA ASRS Text

Title: AN MD88 FLC ENCOUNTERS AN AUTOPLT DISCONNECT DURING THEIR DSCNT TOWARDS 11000 FT AFTER RECEIVING 'ELEVATOR FEEL FAULT,' 'ACU EXCITATION LIGHT' AND THE 'MASTER CAUTION WARNING LIGHT' 30 MI S OF DFW, TX.

Narrative: THIS IS AN EXAMPLE OF HOW A FEW SEEMINGLY INSIGNIFICANT PROBS, WHEN ADDED TOGETHER, CAN LEAD TO A POTENTIALLY SIGNIFICANT PROB. THE AIRPLANE HAD A HISTORY OF AUTOPLT DISCONNECTS DUE TO 'ELEVATOR FEEL FAULT' AND 'ACU EXCITATION' MESSAGES. IT WAS A DARK NIGHT, VERY LITTLE MOONLIGHT AND THERE WERE RAIN SHOWERS AND TSTMS AT THE DEST ARPT, DFW. THERE WERE SIGNIFICANT WINDS AT ALT. WE WERE 30 MI FROM KNEAD INTXN AND HAD A 100 KT TAILWIND. FO BRIEFED AN ILS TO RWY 36L. PASSING 16000 FT AT OUR MAX DSCNT RATE WITH SPEED BRAKES AND WITH A 60 KT TAIL WIND, WE REALIZED WE WOULD NOT MAKE OUR XING RESTRICTION. AT THAT POINT CTR SENT US OVER TO APCH CTL ON 133.62. I ACKNOWLEDGED AND SWITCHED FREQS. I GOT NO ANSWER WHEN I CHECKED IN WITH APCH CTL. AFTER SEVERAL ATTEMPTS I RETURNED TO CTR FOR ANOTHER FREQ AND STILL NO ANSWER. AFTER CHECKING 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 TWO. IN THE MEAN TIME, AS WE APPROACHED 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. FLYING INBOUND TO TTT, I PUT 7600 IN OUR TRANSPONDER BUT CONTINUED TO SEARCH FOR A USABLE FREQ. I MADE CONTACT WITH APCH CTL ON RADIO 2 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 CHECKLISTS. APCH ATTEMPTED ONE 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. THE FACT THAT WE WERE ON AN ARR, BEING RUSHED BY TAIL WINDS, WITH A LATE ROUTE 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: FO DID NOT KNOW WHICH GENERATOR WAS ASSOCIATED WITH THE EXCITATION LIGHT. HE WAS NOT AWARE OF WHAT THE MAINT SIGN OFF WAS FOR THE ACFT FAULTS, IE, AUTOPLT DISCONNECTS, MASTER CAUTION LIGHT, EXCITATION LIGHTS, ELEVATOR FEEL FAULT. HE WAS ALSO UNAWARE AS TO WHETHER THERE WAS A JACK SCREW INSPECTION AS REQUIRED UNDER THE LATEST NTSB/FAA RULING AND IF SO, WHAT WERE THE RESULTS? WHEN ASKED: WAS THE OP OF THE MAIN TRIM MOTOR NORMAL, ANY CIRCUIT BREAKERS FOUND TRIPPED AND WAS THE 'EXCITATION LIGHT' A GENERATOR PWR PROB OR AN AUTOPLT MALFUNCTION, HE WAS NOT ABLE TO ANSWER THOSE QUESTIONS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.