What was found
DURING INSPECTION THE LEFT ENGINE INBOARD EXHAUST STACK WAS FOUND TO BE CRACKED. THE EXHAUST STACK HAS A 1.5 INCH DIAMETER TUBE WELDED TO IT FOR NACELLE INLET DE-ICE. THIS TUBE WAS FOUND CRACKED AROUND THE CIRCUMFERENCE AT ITS WELD ATTACH POINT, AND EXTENDS ALONG THE STACK FLANGE WELD. TOTAL LENGTH IS APPROX 1 INCH. THIS TS THE EIGHTH EXHAUST STACK FOUND CRACKED ON THIS AIRCRAFT. THE OPERATOR HAS REPORTED PREVIOUS CRACKS FOUND ON LEFT AND RIGHT ENGINE, INBOARD AND OUTBOARD SIDES. MANUFACTURING PROCESS IS CURRENTLY BEING EVALUATED AND AN IMPROVED EXHAUST STACK IS BEING DEVELOPED.