What was found
TIST - DURING CLIMB-OUT, AIRCRAFT HAD A VIBRATION. ALL SYSTEMS CHECKED OKAY. ABOUT 2.50 HOURS INTO THE FLIGHT, CREW HEARD A DULL BANG, AND VIBRATION WAS GONE. AFTER LANDING IN GRR, FOUND RIGHT GEAR DOOR WAS MISSING. FORWARD HINGE POINT, BOEING PN 65-26763-2, CRACKED ALLOWING DOOR TO DROP DOWN INTO THE AIRFLOW. THE DOOR FINALLY TORE THE REMAINING ATTACH POINTS LOOSE AND ALLOWED THE DOOR TO DEPART AIRCRAFT. SUBMITTER RECOMMENDS INSPECTION REQUIREMENTS BE UPDATED FOR N.D.T. TO THE HINGE BRACKET AREA EVERY 24 MONTHS OR 1,400 HOURS AT THE 2-C INSPECTION.