What was found
DURING A SCHEDULED INSPECTION, MAINTENANCE DISCOVERED A LARGE CRACK ON THE APU COMPRESSOR CASE HOUSING. PER THE APU OEM, THIS CRACK IS THE RESULT OF A FAILED WELD AND IS A KNOWN CONDITION THAT EXISTS ON AN UNDISCLOSED NUMBER OF UNITS. THE DISCOVERY WAS PRECEEDED BY A HISTORY OF ELEVATED ITT TEMPERATURES (HIGHER THAN TYPICAL BUT NOT OUT OF LIMITS) DURING LOADED CONDITIONS (I.E. ENGINE START) WHICH COULD BE ATTRIBUTED TO THE LOSS OF COOLING AIR AROUND THE COMPRESSOR CASE THROUGH THE CRACK IN THE SHROUD. THE APU WAS REMOVED AND REPLACED.