As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT FROM ABOUT 27,000' WHEN THE ENG ANTI ICE WAS TURNED ON THE NR 1 ENG ANTI ICE VALVE STAYED BRIGHT BLUE. SWITCH WAS CYCLED VALVE DID NOT CLOSE CORRECTLY BUT NOT OPEN. AFTER LANDING PILOT NOTED ON POST WALK AROUND THAT BOTH ENG COWLS WERE WARM ABOUT SAME TEMP. REPLACED NR 1 ENG TAI VALVE PER AMM 30 21 11, RAN ENGINES LEAK CHECK AND OPS CHECK GOOD.