What was found
ON THE GROUND WITH JUST THE APU RUNNING, TURNED ON THE BLEED AIR MAX COOL SWITCH AND ISOLATION VALVE TO OPEN AND SMELLED A BURNING RUBBER ODOR. NO SMOKE OBSERVED.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
ON THE GROUND WITH JUST THE APU RUNNING, TURNED ON THE BLEED AIR MAX COOL SWITCH AND ISOLATION VALVE TO OPEN AND SMELLED A BURNING RUBBER ODOR. NO SMOKE OBSERVED.