What was found
ON THE GROUND ILLUMINATION OF TR & MAINT LIGHT ON APU BUS, DISCONNECTED GROUND PWR, 60 SECONDS LATER LOST ALL POWER, LOST FO INSTRUMENTATION. TR UNIT & MAINT LIGHTS ILLUMINATED. SMOKE IN COCKPIT. SMOKE ALSO REPORTED FROM THE AFT OF THE AIRCRAFT. GROUNDED - YES. REF TSR718071 FOR T/S AND WORK ACCOMPLISHED, AND BACK OF P91 DISTRIBUTION PANEL INSPECTED FOUND C PHASE TERMINAL ON TB5002 BURNED, ALONG WITH W4722-0010-1/0 AND 0508-06 WIRE TERMINALS BURNT. REMOVED AND REPLACED P91 DISTRIBUTION PANEL REF AMM 24-21-21.