As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX - THE CREW WAS DESCENDING THRU FL220 AND NOTICED A LOW FREQ VIBRATION (AVIONICS BAY) FOLLOWED BY TOXIC FUMES. THE CREW DONNED O2 MASKS. THE CREW RECEIVED AN EXTRACT FAN "FAULT" LIGHT. THE CREW DECLARED AN EMERGENCY. THE LANDING WAS UNEVENTFUL. MX REPLACED (18HQ) EXTRACT FAN IAW AMM 21-26-51. OPS CHECK WAS GOOD. MX ALSO RESET TR1 AND PERFORMED OPERATIONAL TEST OF THE DC GENERATION SWITCHING. OPS CHECK WAS GOOD.