Narrative:

Departed mke at approximately XA00 am local time. Preflight and runup checks were normal. Mke departure reported difficulty reading transponder. After recycling, no further difficulty was reported. At about the same time, departure reported the same difficulty with another aircraft. I proceeded south along the lake shore, contacted waukegan, meigs and gary towers with no trouble. Gary requested identify on the transponder and received signal. Shortly before leaving gary's airspace, static began in the communication system, and quickly became so loud as to prevent hearing any outside communications. All radio reception was intermittent and digital readouts came on and off at random. There had been no indication of anything unusual in the alternator (ammeter, low voltage light) during routine instrument scans throughout the flight. I don't know if gary attempted a final radio call since handoff outside their airspace had not been formally acknowledged. At this point all radios and other electric readouts failed. I ran through the checklist procedure for electric failure. Only 1 circuit breaker, for the beacon, had popped. I shut down all non-essential equipment and tried to re-establish voice communication with 1 radio. Power was intermittent, indicating some battery charge remained. Indicated 7600 on the transponder. At this point, location was between michigan city and benton harbor, along the lake shore. I didn't know the cause of the failure, so decided to land and attempt a better diagnostic procedure. I tried 1 unicom call to michigan city, indicating radio failure. I shut down all electrical equipment and proceeded to benton harbor. I observed local traffic taking off, determined active runway, and entered traffic pattern. On final, I turned on electrical system once more. Radios did not function. Minimal flap deployment was possible. Landed and shut the plane down at the terminal ramp. Unable to restart afterwards. According to the mechanic at the plane's home base, the leads to the alternator were not connecting consistently. The alternator had been replaced about 2 weeks prior to this occurrence because of other reported electrical problems. The communications failure was clearly a result of the alternator problem. Attempts were made to diagnose the problem. I remained clear of controled airspace and attempted to fix the problem.

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Original NASA ASRS Text

Title: ACFT EQUIP PROB. ALTERNATOR LEADS LOOSE RESULTING IN ELECTRICAL COM FAILURE.

Narrative: DEPARTED MKE AT APPROX XA00 AM LCL TIME. PREFLT AND RUNUP CHKS WERE NORMAL. MKE DEP RPTED DIFFICULTY READING XPONDER. AFTER RECYCLING, NO FURTHER DIFFICULTY WAS RPTED. AT ABOUT THE SAME TIME, DEP RPTED THE SAME DIFFICULTY WITH ANOTHER ACFT. I PROCEEDED S ALONG THE LAKE SHORE, CONTACTED WAUKEGAN, MEIGS AND GARY TWRS WITH NO TROUBLE. GARY REQUESTED IDENT ON THE XPONDER AND RECEIVED SIGNAL. SHORTLY BEFORE LEAVING GARY'S AIRSPACE, STATIC BEGAN IN THE COM SYS, AND QUICKLY BECAME SO LOUD AS TO PREVENT HEARING ANY OUTSIDE COMS. ALL RADIO RECEPTION WAS INTERMITTENT AND DIGITAL READOUTS CAME ON AND OFF AT RANDOM. THERE HAD BEEN NO INDICATION OF ANYTHING UNUSUAL IN THE ALTERNATOR (AMMETER, LOW VOLTAGE LIGHT) DURING ROUTINE INST SCANS THROUGHOUT THE FLT. I DON'T KNOW IF GARY ATTEMPTED A FINAL RADIO CALL SINCE HDOF OUTSIDE THEIR AIRSPACE HAD NOT BEEN FORMALLY ACKNOWLEDGED. AT THIS POINT ALL RADIOS AND OTHER ELECTRIC READOUTS FAILED. I RAN THROUGH THE CHKLIST PROC FOR ELECTRIC FAILURE. ONLY 1 CIRCUIT BREAKER, FOR THE BEACON, HAD POPPED. I SHUT DOWN ALL NON-ESSENTIAL EQUIP AND TRIED TO RE-ESTABLISH VOICE COM WITH 1 RADIO. PWR WAS INTERMITTENT, INDICATING SOME BATTERY CHARGE REMAINED. INDICATED 7600 ON THE XPONDER. AT THIS POINT, LOCATION WAS BTWN MICHIGAN CITY AND BENTON HARBOR, ALONG THE LAKE SHORE. I DIDN'T KNOW THE CAUSE OF THE FAILURE, SO DECIDED TO LAND AND ATTEMPT A BETTER DIAGNOSTIC PROC. I TRIED 1 UNICOM CALL TO MICHIGAN CITY, INDICATING RADIO FAILURE. I SHUT DOWN ALL ELECTRICAL EQUIP AND PROCEEDED TO BENTON HARBOR. I OBSERVED LCL TFC TAKING OFF, DETERMINED ACTIVE RWY, AND ENTERED TFC PATTERN. ON FINAL, I TURNED ON ELECTRICAL SYS ONCE MORE. RADIOS DID NOT FUNCTION. MINIMAL FLAP DEPLOYMENT WAS POSSIBLE. LANDED AND SHUT THE PLANE DOWN AT THE TERMINAL RAMP. UNABLE TO RESTART AFTERWARDS. ACCORDING TO THE MECH AT THE PLANE'S HOME BASE, THE LEADS TO THE ALTERNATOR WERE NOT CONNECTING CONSISTENTLY. THE ALTERNATOR HAD BEEN REPLACED ABOUT 2 WKS PRIOR TO THIS OCCURRENCE BECAUSE OF OTHER RPTED ELECTRICAL PROBS. THE COMS FAILURE WAS CLRLY A RESULT OF THE ALTERNATOR PROB. ATTEMPTS WERE MADE TO DIAGNOSE THE PROB. I REMAINED CLR OF CTLED AIRSPACE AND ATTEMPTED TO FIX THE PROB.

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.