PLT OF AN SMA SEL HAD THE LNDG GEAR COLLAPSE AFTER THE EMER EXTENSION OF THE GEAR DUE TO TOTAL ELECTRICAL FAILURE.

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I WAS PLTING MY COMANCHE 250 WHEN ELECTRICAL FAILURE WAS NOTICED. I DEPARTED FBO AFTER A NORMAL RUNUP OF THE AIRPLANE. I WAS FLYING E AND UNDER VFR FLT FOLLOWING WITH ZOB. MY CRUISE ALT WAS 7500 FT MSL AND APPROX 20 NM FROM PHILLIPSBURG VOR; WHEN SCANNING PANEL; I NOTICED NEGATIVE GENERATOR OUTPUT. I IMMEDIATELY REQUESTED DEV TO P53 (ROSTRAVER) FROM ZOB. I STILL HAD A FULL PANEL ELECTRICALLY BUT TURNED OFF ALL BUT ESSENTIAL ELECTRICAL ITEMS IN ORDER TO CONSERVE BATTERY PWR. AFTER BEING HANDED OFF TO PITTSBURGH AND MAKING THEM AWARE OF MY SIT; I TRIED TO LOWER MY LNDG GEAR. 1/2 WAY THROUGH THE CYCLE; THE WHOLE PANEL WENT DEAD. I CONFIRMED NO BREAKERS WERE TRIPPED AND DECIDED TO EXECUTE EMER GEAR EXTENSION. THE LNDG GEAR APPEARED TO BE LOCKED AS I HEARD THE MAIN GEAR 'SNAP' INTO PLACE; BUT WITH NO ELECTRIC I COULD NOT CONFIRM IF THEY WERE ACTUALLY 'LOCKED' AS THE INDICATORS ARE ELECTRICALLY DRIVEN. I ARRIVED AT P53 WITH STILL NO ELECTRIC AND CIRCLED 500 FT ABOVE TFC PATTERN ALT WHILE I TRIED TO REACH THE MECH ON THE GND WITH MY CELLULAR PHONE AS I WANTED TO CONFIRM THE GEAR WAS LOCKED AND DOWN. I COULD NOT CONTACT GND PERSONNEL AND THEN DOUBLE CHKED THE MANUAL GEAR EXTENSION. FEELING CONFIDENT EVERYTHING WAS NORMAL; I MADE A NORMAL ENTRY TO LAND ON RWY 7. UPON TOUCHDOWN; I FELT THE WHEELS COLLAPSE AND THE PLANE SKIDDED TO A STOP. NO INJURIES WERE EXPERIENCED AND NO DAMAGE TO ARPT PROPERTY OCCURRED. I HAD MY PLANE IN THE REPAIR SHOP TO REPAIR A TRIPPED NAV AND PANEL LIGHT BREAKER 5 DAYS PREVIOUS. NO ELECTRICAL PROBS WERE ENCOUNTERED WITH THE MECH. IN DISCUSSIONS WITH AN FAA REPRESENTATIVE; HE SAID GENERATORS WERE 'UNRELIABLE' AND OLD TECHNOLOGY. IF THIS IS THE CASE; I FEEL ALL PLANES SHOULD BE CONVERTED TO ALTERNATORS. ALSO; IN THIS MODEL OF AIRPLANE; A NICAD BATTERY BACKUP FOR THE LNDG GEAR EXTENSION LIGHTS WOULD HELP PLTS CONFIRM FULL EXTENSION OF LNDG GEAR. IT HAS NOT BEEN DETERMINED IF MECHANICAL MALFUNCTION WITH THE GEAR OCCURRED BUT BACKUP BATTERY PWR WOULD BENEFIT US GREATLY.