What was found
HAIRLINE CRACK DEVELOPED IN LEFT WINDOW, CRUISING AT .74 AND FL310. STARTED DESCENT INTO CLARKSBURG, GOT L WINDOW HEAT CAUTION MESSAGE. FOLLOWED QRH, OBVIOUSLY DIDN€™T FIX CRACK. CRACK GOES FROM (INSIDE LOOKING OUT) ABOUT 5-6 INCHES FROM BOTTOM RIGHT CORNER TO ABOUT MIDDLE OF WINDOW. FLIGHT 5108. REMOVED AND REPLACED LH SIDE WINDOW IN REFERENCE TO AMM AND MIP TASK. OPS CHECK GOOD AT THIS TIME. PRESSURIZATION/LEAK CHECK GOOD.