THE PILOTS IMPROPER PREFLIGHT INSPECTION, HIS FAILURE TO COMPELTELY SECURE THE AFT UTILITY DOOR, AND HIS FAILURE TO RECONFIGURE THE TRIM TABS TO A TAKEOFF SETTING. THE UTILITY DOOR'S SUDDEN OPENING JUST AFTER ROTATION AND THE EFFECT OF THE NOSE UP TRIM SETTING LED TO AN INADVERTENT STALL DURING THE TAKEOFF INITIAL CLIMB.