INSTRUCTOR AND ADVANCED STUDENT ABOARD PA28 SUFFER COMPLETE ELECTRICAL FAILURE WHICH RESULTS IN INCOMPLETE LANDING GEAR EXTENSION AND SUBSEQUENT COLLAPSE ON LANDING.

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I WAS GIVING DUAL INSTRUCTION TO A COMMERCIAL MULTI-INST RATED PLT FOR HIS INST PROFICIENCY CHK. WE BEGAN THE IPC WITH A HOLD OVER THE ZZZ1 VOR. ATC RPTED THAT THEY LOST OUR XPONDER; SO WE TRIED TO CYCLE THE XPONDER. AFTER MY SECOND COM WITH ATC; MY FIRST RADIO PANEL BEGAN TO SCRAMBLE AND SLOWLY BURNT OUT. THEN SHORTLY AFTER THE SECOND RADIO PANEL DID THE SAME THING; AND I WAS LEFT WITH NO RADIO AND ELECTRICAL FUNCTIONS. I THEN MADE THE DECISION TO DEPART CLASS C AIRSPACE AND GO TO ZZZ2 WHICH WAS AN UNCTLED ARPT FOR MY LNDG THERE. ONCE WE DEPARTED THE HOLD; I SQUAWKED 7600 ON MY XPONDER AND CONTINUED TO ZZZ2. I OVERFLEW THE FIELD AT 2500 FT AND FOUND THAT RWY X WAS IN USE AT ZZZ2. I TURNED ON AN EXTENDED DOWNWIND SO I COULD SEE AND AVOID ALL TFC. I HAD NO WAY TO CONTACT ANYONE TO STATE MY INTENTIONS. I THEN WENT THROUGH MY DSCNT PROCS AND FOUND THAT I HAD NO INDICATIONS THAT MY GEAR WAS DOWN. I HAD NO GREEN; RED UNSAFE; GEAR IN TRANSITION LIGHTS OR AURAL WARNING WHEN THROTTLE WAS REDUCED. I THEN DECIDED TO DO A MANUAL GEAR EXTENSION SO I SLOWED TO 60 KTS AND DROPPED THE MANUAL GEAR KNOB. I DID APPROX 5-6 S-TURNS WITH EXTENSIVE RUDDER INPUTS TO YAW THE ACFT TO ENSURE THE GEAR WAS IN THE LOCKED POS AND ALSO FOR SPACING BEHIND A C172. I WAS ON AN APPROX 2 MI FINAL. I THEN CONTINUED FOR THE LNDG. I HAD NO WAY TO CONTACT ANYONE ON THE GND OR IN THE AIR TO VISUALLY CHK MY GEAR. WHILE TOUCHING DOWN I FELT THE GEAR UNDERNEATH ME COLLAPSE. I HELD THE NOSE OF THE ACFT OFF AS LONG AS POSSIBLE AND SHUT DOWN THE AIRPLANE. I DID NOT SHUT IT DOWN QUICKLY ENOUGH TO PREVENT ENG STOPPAGE. I THEN CAME TO A COMPLETE STOP ON THE CTRLINE OF RWY X AND BOTH MY STUDENT AND I EXITED THE ACFT.