What was found
THERE ARE 4 SCREWS WHICH HOLD THE ELEVATOR TRIM TAB HORN TO THE TRIM TAB. HAVE STARTED TO REMOVE THESE SCREWS ON EVERY ANNUAL WE DO ON 300/400 SERIES. HAVE FOUND NUMEROUS SCREWS CORRODED ALMOST IN HALF. THERE IS NOT A WAY TO INSPECT THESE SCREWS WITHOUT REMOVAL. DUE TO THE CRITICAL NATURE OF THESE SCREWS AND THE AGEING FLEET. RECOMMEND MANDITORY REMOVAL AND INSPECTION AT EACH ANNUAL INSPECTION. (K)