What was found
ON CONTROL CHECK, RIGHT HAND INBOARD SPOILER DOE NOT FULLY DEPLOY.. REMOVED FROM SERVICE. INTERROGATED CDS AND PSEU WITH NO F/C'S, NO CAUTION MESSAGES PER PILOT. PERFORMED ENGINE RUN AND OPS TEST OF ROLL SPOILER SYSTEM REF Q400 AMM 27-61-00-710-801. ISSUE ONLY DUPLICATES WHEN FLIGHT/TAXI SWITCH IN TAXI MODE. REPLACED RH INBD PCU IAW Q400 AMM 27-61-21-000/400-801. OPS CHECK GOOD. A/C IS CLEARED FOR RTS. COMPLETED FREEDOM OF MOVEMENT CHECK, ENSURED FULL TRAVEL AND VERIFIED PROPER DIRECTION OF MOVEMENT, NO DEFECTS NOTED PER GPM 9.2 (FREEDOM OF MOVEMENT CHECK).