What was found
AS PART OF INSPECTION, DEICE CONTROL AND MANIFOLD ARE CHECKED. FOUND MANIFOLD NOT OPERATING CORRECTLY. INTERNAL CHECK VALVES NOT SEALING WHEN AIR BLOWN IN ONE INLET AT A TIME. THIS COULD HAVE AN EFFORT ON BOOT OPERATION IF ONE VACUUM PUMP FAILED BY ALLOWING SOME PRESSURE TO RUN BACK THROUGH INOPERATIVE PUMP. AIRBORNE PRODUCT REF MEMO NR 39 RECOMMENDS REPLACEMENT AFTER 10 YEARS. PART REPLACED ON THIS AIRCRAFT WAS 10 YEARS OLD.