As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FLIGHT CREW REPORTS STRONG MUSTY SMELL IN CABIN AND COCKPIT WITH APU AND PACKS ON. MAINTENANCE ACCOMPLISHED CARD 05-96-70 AND DETERMINED THAT THE APU IS THE SOURCE OF THE ODOR. MAINTENANCE FOUND OIL IN THE 6 O'CLOCK LOAD COMPRESSOR DRAIN LINE AND OIL SMELL IN THE AIR DUCT TO LOAD CONTROL VALVE. APU CHANGE DECLARED. MAINTENANCE REMOVED AND REPLACED THE APU IAW JOB CARD 49-94-11. OPS CHECK NORMAL. NO LEAKS NOTED. NO FURTHER ODORS NOTED.