What was found
A CRACK DEVELOPED AT THE FORWARD FLANGE OF THE AFT INNER BYPASS DUCT AT THE 6 O'CLOCK POSITION ALLOWING IT TO COME OUT OF THE MATING FLANGE AND ENTER THE AIR FLOW, THEREBY CAUSING A 3 INCH (APPROX) SECTION TO PEEL BACK AND CAUSE A 2 INCH (APPROX) TEAR ALONG THE RADIUS OF THE BEND. THE PILOT NOTICED THE PIECE HANGING DOWN DURING PRE-FLIGHT INSPECTION AND ASSY WAS REPLACED BEFORE FURTHER FLIGHT.