What was found
FOUND CAPACITOR IN UNIT LOOSE, AND SIDE COVER MOUNTING HARDWARE LOOSE AND ARCING TO DC BUSS OF AIRCRAFT. CAUSED BULB FILAMENT TO BECOME FUSED TO UPRIGHTS OF FILAMENT. THIS WAS PRODUCING A 5 VAC PULSE AT 50 MICROSEC ON THE DC BUSS OF AIRCRAFT WHICH SHUT DOWN BOTH AC INVERTERS. CAUSED TAIL DE-ICE CONTROL BOX TO LOCK UP IN A STATE OF FAILURE AND LANDING FLAP DELAY. FIRST FAILURE, 216 TT 7-2-95, 2ND FAILURE 2-11-97. RECOMMEND DIFFERENT STYLE OF SIDE COVERS ON ANTI-COLLISION LIGHT.