As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 2588 - BIL - ON FINAL INTO BILLINGS, THE CREW NOTICED THE RIGHT ACM STARTED TO BLOW SMOKE AND THEY NOTICED A SMELL. THE RIGHT ACM WAS SHUTOFF AND CREW LANDED WITH NO FURTHER INCIDENT. RIGHT ACM HAD FAILED. ACM WAS INITIALLY DEFERRED, THEN WAS REPLACED. SYSTEM OPS CHECKED GOOD. (M)