As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDIS 630 21-01 2097683 20MAY19 GSO CLOSE IN CRUISE FLIGHT AT 25K BOTH FLIGHT DECK AND CABIN EXPERIENCED LIGHT SMOKE. C/W QRH PROCEDURE AND SMOKE DISSIPATED 24934 00 EK HISTORY: FACT 21MAY19 12:02 GSO R&R NR 1 AIR CYCLE MACHIINE IAW 21-51-03. OPS CHECK GOOD. NO DEFECTS NOTED AT THIS TIME.