PA23 PILOT REPORTS ELECTRICAL SYSTEM FAILURE DURING OVERWATER FLIGHT AT LOW ALTITUDE.

Narrative

PIPER AZTEC JUST COMPLETED A L ENG FULL OVERHAUL; REMOVAL OF TURBOCHARGER SYS AND REPLACEMENT WITH STRAIGHT EXHAUST PIPES; AND ANNUAL. TEST FLEW AIRPLANE WITH A PLT/MECH AND PLT ON BOARD ON THE MORNING OF JUN/XA/08. NOTED THROTTLES NOT BALANCED; RETURNED PLANE TO SHOP FOR BALANCING. FILED FLT PLAN. THROTTLES BALANCED; TOOK OFF WITH 3 PAX FROM ZZZ1. ACTIVATED FLT PLAN ABOUT XA40Z. ABOUT 15 MINS AFTER DEP; NOTED THAT AMMETERS WERE SHOWING BATTERY STILL CHARGING -- FIGURED BATTERY WAS LOW AND NEEDED CHARGING; KEPT EYE ON AMMETERS. AFTER 30 MINS; AMMETER STILL SHOWED CHARGING. DECIDED TO TURN AROUND AND RETURN TO UNITED STATES OF AMERICA. WANTED TO TURN OFF ALTERNATORS BUT REMEMBERED HANDBOOK SAID NOT TO; CHKED HANDBOOK; SECTION II; ELECTRICAL SYS 'THE ALTERNATOR CIRCUIT BREAKERS; MOUNTED ON THE SAME PANEL; ARE OF THE SWITCH TYPE AND SHOULD NOT BE TURNED OFF WHILE THE ENGS ARE RUNNING.' WORRIED THAT THE ALTERNATORS MIGHT OVERCHARGE THE BATTERY; TURNED ON NAV; LNDG; AND TAXI LIGHTS. ABOUT 5 MINS LATER; INST PANEL STARTED TO SMOKE AND ELECTRICAL SYS TRIPPED OFF. READ EMER PROCS -- SAID TURN OFF ALTERNATORS. TURNED ON 2 HANDHELD RADIOS AND BATTERY POWERED GPS. ABOUT EVERY 5 MINS; XMITTED ON FREQ 'AZTEC ON FLT PLAN FROM ZZZ1 XMITTING IN THE BLIND; LOST BATTERY; NO ELECTRONICS; DECLARING EMER; MY INTENTION IS TO RETURN TO ZZZ2.' FLEW S WHILE GPS ACQUIRED SIGNAL; CONSULTED NEW CHART; EXPLAINED TO PAX THAT MY PLAN WAS TO INTERSECT XX.30N THEN FLY DUE W WHICH WOULD TAKE ME JUST S OF ZZZ1; THEN APCH ZZZ1 AT 1000 FT TO STAY BELOW ZZZ2 AIRSPACE. FINALLY GPS ACQUIRED; I INTERSECTED; FLEW W; VARIABLE VISIBILITY. AS NEARED LAND BROADCASTED INTENTIONS. AS WE SIGHTED LAND; DID NOT RECOGNIZE LANDSCAPE; REALIZED NOT WHERE I THOUGHT I WAS; STUDIED CHART AND REALIZED I HAD BEEN FLYING W ON YY.30N INSTEAD OF XX.30N. CONSIDERED WHETHER TO GO TO ZZZ3 OR ZZZ1. DECIDED PLANE WAS STABLE; LOTS OF ARPTS ENRTE; NOT FAMILIAR WITH ZZZ3 AND NO ELECTRONICS; SAFEST TO CONTINUE TO ZZZ1. NOTED THAT I WAS ALREADY IN ZZZ MODE C AREA BUT WAS UNDER THE 3000 FT AIRSPACE FLOOR. FLEW N STAYING CLR OF ZZZ AIRSPACE. APCHING ZZZ4; NOTED AIRSPACE AND FLEW OUT TO SEA TO AVOID. CONTINUED TO ZZZ2; SWITCHED FREQ AND BROADCAST 'PIPER AZTEC NO ELECTRICAL; USING HANDHELD RADIO; DECLARING EMER; PLEASE STAY CLR OF RWY 9; LNDG RWY 9 IN 5 MINS.' '...3 MINS.' '...ON FINAL. '...SHORT FINAL.' LANDED; TAXIED TO MECH; DISEMBARKED PAX; CALLED CUSTOMS (RECEIVED INSTRUCTIONS TO WAIT BY PLANE); CLOSED FLT PLAN. MECHS LOOKED; BATTERY HAD EXPLODED. AFTER MEETING WITH ABOUT 5 SHERIFF AND CUSTOMS AND BORDER AGENTS (THEY HAD THOUGHT RADAR HAD SHOWED ME LNDG IN ZZZ3); FILED ARR RPT AND CLRED TO DEPART. RECEIVED A PHONE CALL FROM AN AGENT TO CALL MR X. I EXPLAINED WHAT HAD HAPPENED. HE EXPLAINED THAT MY MODE C WAS OUT SO THEY DID NOT KNOW MY ALT OR INTENTIONS. THEY ASSUMED I WAS AT 3000 FT; CLOSED ZZZ AND ZZZ4 AIRSPACE UNTIL I PASSED; WOULD FILE A RPT. TODAY CALLED MECH; LEARNED THAT ALTERNATOR SWITCHES WERE FRIED; THAT VOLTAGE REGULATORS AND OVERLOAD PROTECTION MAY HAVE BEEN BAD.