What was found
PILOT REPORTED THAT THE LANDING GEAR ON RT MAIN "A" SYS INDICATED DOWN AND LOCKED AT FL 260, HANDLE WAS UP AND LANDING GEAR "B" SYSTEM IS ON DML. MAINTENANCE REPLACED THE LANDING GEAR CONTROL MODULE PN 120-38594-001 SN ON 120247, SN OFF 120069R, IAW EMB120 MM 32-31-01, PERFORMED FUNCTIONAL CHECKS OK.