What was found
ON CLIMB THROUGH ABOUT 15000 ' DEICE PRESS CAUTION ILLUMINATED. RAN DEICE PRESS CAUTION CHECKLIST. DEICE PRESS CAUTION EXTINGUISHED, THEN RE-ILLUMINATED. FOUND RIGHT HAND ENGINE INTAKE BOOT NOT INFLATING. DEICE PRESSURE INDICATED BETWEEN 16-18 PSI FOR EVERY BOOT SEGMENT INFLATION. AIRCRAFT WAS OPERATING IN ICING CONDITIONS AT 15,000'. DIVERTED. REMOVED FROM SERVICE. GROUND RAN ENGINE. INTERROGATED CDS FOUND DEICE LOW PRESS. 4A FAIL.MSG., CLEARED CDS. R&R'D #4 DEICE DIST. VALVE IAW Q400 AMM TASKS 30-11-16-000-801/400-801. OPS CKS GOOD, FAULT CODE DID NOT RE-OCCUR. AIRCRAFT RETURNED TO SERVICE.