What was found
WHEN PILOT OPENED CABIN DOOR, A GUST OF WIND CAUGHT DOOR AND SLAMMED IT INTO STOP. PILOT REPORTED A LOUD (POP) AND PAINT FELL FROM DOOR HINGE. INSPECTION REVEALED LOWER LEG OF DOOR HINGE HAD BROKEN. DISASSEMBLY REVEALED EVIDENCE OF A PRE EXISTING SUBSURFACE CRACK IN CASTING, 3 INCH AFT OF HINGE BEARING. A SURFACE CRACK 1INCH LONG 1.5 INCH AFT OF HINGE BEARING WAS HIDDEN BY HEAVY PAINT COATING. THESE CRACKS WOULD NOT BE VISIBLE WITHOUT PAINT REMOVAL. RECOMMEND PAINT BE REMOVED AND CAST PORTION OF HINGE INSPECTED UNDER MAGNIFICATION AT 500 HR INTERVALS.