C421 WITH ELECTRICAL FAILURE AND NO COM ENTERED CLASS D TFC PATTERN WITH TWR FLY-BY AND DURING APCH FLEW ACROSS ANOTHER ACFT IN THE PATTERN. ELECTRICAL PROB CAUSED BY ALTERNATOR CIRCUIT BREAKERS BEING OUT.

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FLYING FROM SAN CARLOS ARPT TO SACRAMENTO EXECUTIVE ARPT IN OUR C421 GOLDEN EAGLE; ELECTRICAL PROBS BEGAN TO OCCUR. FLYING WITH ME WAS ANOTHER QUALIFIED ATP PLT WITH OUR 2 WIVES AS PAX. IN THE VICINITY OF PITTSBURG; CA; JUST NE OF MT DIABLO; AT AN ALT OF 3500 FT; THE AUTOPLT FAILED; FLAGS WERE COMING UP ON THE VOR OF THE HSI AND OTHER ELECTRICAL INSTS HAD FAILED OR WERE FAILING. THE DECISION WAS MADE TO RETURN TO SAN CARLOS. ALL ELECTRICAL EQUIP WAS SHUT DOWN. NO FAILURE LIGHT SHOWED ON THE ANNUNCIATOR. ALL RADIOS WERE SHUT OFF IN ORDER TO PRESERVE COM FOR LNDG. WITH RADIOS AND ELECTRICAL SYS OUT; EVERY EFFORT WAS MADE TO STAY OUT OF CLASS B AIRSPACE. THE SHORELINE WAS CROSSED NEAR KGO TWR ON THE E SIDE OF THE BAY AND A HDG TAKEN DIRECT TO KNBR TWR; DROPPING TO 1000 FT ALT. ON THE W SIDE OF THE BAY OUR INTENTION WAS TO MAKE A NO RADIO APCH TO SAN CARLOS ARPT. MID BAY; AN ATTEMPT WAS MADE TO LOWER THE LNDG GEAR. IT APPEARED TO EXTEND; HOWEVER; THE FINAL LOCK IN PLACE WAS NOT HEARD AND THERE WERE NO GREEN 'DOWN AND LOCKED' LIGHTS. SINCE THERE WAS NO CERTAINTY THAT THE GEAR WAS DOWN; A MANUAL EXTENSION WAS PERFORMED FOR ADDITIONAL CONFIRMATION. APCHING KNBR; THE COM RADIO WAS TURNED ON. THERE WAS ENOUGH BATTERY LEFT TO RECEIVE; BUT OUR XMISSION WAS GARBLED AND WITHIN A MIN OR SO THE RADIO COMPLETELY FAILED. A 45 DEG ENTRY WAS MADE FROM THE VICINITY OF KNBR. THERE WAS ANOTHER SMALL HIGH WING ACFT TO THE L AND DOWNWIND. CONSIDERING THAT THE C421 WAS MUCH FASTER THAN THE OTHER ACFT AND OUR DESIRE TO ATTRACT THE TWR; THE DECISION WAS MADE TO MAKE A BASE TURN CLR OF THE OTHER ACFT'S FLT PATH. THE OTHER ACFT'S FLT PATH ON DOWNWIND WAS PAST OUR FLT PATH. WE MADE OUR BASE TURN WELL CLR OF THE OTHER ACFT AND PROCEEDED ON FINAL TO RWY 30 FOR A FLY-BY OVER THE FIELD AND TO ALERT THE TWR OF OUR CONDITION. THE WINGS WERE ROCKED; HOWEVER; THE TWR STATES THE ROCKING WINGS WERE NOT OBSERVED. THE TWR DID UNDERSTAND THAT WE WERE HAVING A PROB AND GAVE US A RED LIGHT. WE CONTINUED OVER THE FIELD AND DOWNWIND TO BASE FOR RWY 30. THE TWR GAVE US A GREEN LIGHT; OUR MANUAL EXTENSION CERTIFIED THE WHEELS DOWN AND LOCKED; AND WE MADE AN UNEVENTFUL NO FLAP LNDG. SUBSEQUENT TO LNDG THE TWR WAS CALLED AND THE SIT DISCUSSED WITH THE TWR OPERATOR. THEY SUGGESTED THAT THEY WOULD HAVE LIKED TO HAVE OBSERVED MORE POSITIVE ROCKING OF THE WINGS. SHORTLY AFTER THE TWR CONVERSATION; ANOTHER PLT CAME TO OUR HANGAR AND ADVISED US THAT IN MAKING OUR GAR WE WERE ONLY A FEW HUNDRED FT ABOVE HIS SMALL CESSNA (C150 OR C172) AS HE WAS LNDG. THIS SMALL LNDG ACFT WAS NOT OBSERVED TO BE UNDER OUR ACFT. THERE IS A POSSIBILITY THAT THE ALTERNATORS WERE NOT PROVIDING VOLTAGE OR CHARGING THE BATTERIES. THE USUAL ALTERNATOR CHK WAS MADE. THERE WAS NO FAILURE LIGHT. THE VOLTAGE MAY HAVE BEEN MISREAD. THE VOLTAGE READING COULD HAVE BEEN 24 VOLTS; NOT 28 VOLTS WHICH COULD HAVE INDICATED ALTERNATORS OUT. THE FAILURE OF THE ANNUNCIATION LIGHTS TO COME ON FROM THE BATTERY IS STILL A PUZZLE IF THE ALTERNATORS WERE INOP. IN ADDITION; THE ALTERNATOR CIRCUIT BREAKERS ARE VERY FAR IN THE REAR OF THE CIRCUIT BREAKER CONSOLE WHICH MADE IT VERY DIFFICULT TO DETERMINE IF THEY WERE SET IN POS PROPERLY; PARTICULARLY WHEN THERE WAS NO ALTERNATOR FAILURE LIGHT. THE C421 HAD JUST BEEN RETURNED FROM MAINT ON APR/XA/98; THE DAY BEFORE. THE ELECTRICAL SYS HAD NOT BEEN RESTORED TO FLYABLE CONDITION. THIS WAS NOT OBSERVED UNTIL APR/XC/98 WHEN A RECONSTRUCTION OF THE PROBS INDICATED THAT THE ALTERNATOR CIRCUIT BREAKER MAY HAVE BEEN PULLED AND ALSO THE FIELD FUSES WERE LOOSE AND APPEARED NOT TO BE MAKING CONTACT. THE IMPORTANT MESSAGE FROM THE EXPERIENCE IS TO MAKE SURE THE CORRECT VOLTAGE IS BEING READ AND DOUBLECHK ALL CIRCUIT BREAKERS.