As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER ENGINE START, RIGHT ACU FAIL LIGHT ILLUMINATED. CABIN AREA FILLED WITH SMOKE, A/C EVACUATED/SECURED. RIGHT FLEX COUPLING FAILED DUE TO OVERTEMP. 400 DEGREE SWITCH FOUND TO TRIP AT 590 DEGREES. SEE SDR CA990318043 FOR NOTES ON INVESTIGATION.