As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: MUSTY ODOR- DIRTY SOCK SMELL DURING DESCENT WITH HP BLEED VALVES OPEN. ODOR DISSIPATES WHEN POWER IS INCREASED. REPLACED 4 EACH O-RINGS ON APU TRANSFER TUBES TO APU OIL COOLER PER AMM 49-91-44. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO ODORS NOTED.