What was found
AC WAS RETURNING TO HOME FIELD AFTER MAINTENANCE WHEN CREW HEARD A LOUD NOISE AND ELECTED TO RETURN TO DEPARTURE. AFTER ENGINE SHUT-DOWN, IT WAS DETERMINED THAT THE LT ENGINE UPPER AND LOWER COWLING HAD SEPARATED FROM THE AC IN FLIGHT. SB CONCERNING COWLING SEPARATION, HAD BEEN PREVIOUSLY APPLIED. COWL SEPARATION HAS BEEN THE SUBJECT OF PREVIOUS SERVICE AD AND SERVICE NEWS FLASHES. (K)