As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRSHUTTLE 7566 - DEN-GJT - INFLIGHT, THE COCKPIT FILLED WITH SMOKE AND FUMES. THE CREW USED THE O2 MASKS AND PROCEEDED TO GJT WITH NO FURTHER INCIDENT. MAINTENANCE TEST FLEW AIRCRAFT AND COULD NOT DUPLICATED THE DISCREPANCY. AIRCRAFT WAS RETURNED TO SERVICE. (M)