What was found
APU SHUTDOWN AFTER LOUD BANG AND BRIGHT WHITE LIGHT FOLLOWED BY LOTS OF SMOKE. PLACED ON MEL 49-00-1. CLEARED MEL 10/27/09 INTERIGATED CDS NO PRESENT FAULTS, PREVIOUSLY FAULTS 131 & 124, CLEANED CONNECTORS ON EGT AND SPEED SENSOR, C/W COMBUSTION DRAIN VALVE INSPECTION IAW HS49-0007, STARTED APU TWO TIMES AND OPERATED UNDER FULL LOAD ELECT & BLEED AIR, NO DEFECTS NOTED. RETURNED TO SERVICE. NO PARTS REPLACED.