As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. DURING FUNCTIONAL CHECK FLIGHT AT 19,000 FEET, FIRST OFFICER AND CAPTAIN BOTH NOTICED ODOR FROM VENTS WHEN APU BLEED ENGAGED THEN OFF AND ENGINE BLEEDS BACK ON. REMOVED AND REPLACED AUXILIARY POWER UNIT PER JOB CARD 26L31049005. OPERATIONAL CHECK GOOD.