What was found
DURING A PHASE 3 INSPECTION, A 1.50 INCH CRACK WAS NOTED ABOVE THE LEFT ENGINE, NR 2 CYLINDER. PER M90-17, THIS WAS IN A NON-CRITICAL AREA, SO THE CRACK WAS SCRIBE MARKED AND RETURNED TO SERVICE. DURING THE PHASE 4 INSPECTION, THE CRACK WAS NOTED TO HAVE PROGRESSED BY .50 INCH (BEYOND LIMITS PER M90-17). SUBMITTER SUGGESTED POSSIBLE CAUSE AS MANUFACTURING DEFECTS. ENGINE TO BE REMOVED FOR OVERHAUL.