What was found
AIRCRAFT HAS OILY ODOR, VERY STRONG, LIKE DIRTY SOCKS OR VAPORZED OIL. PACKS WITH GROUND AIR CART, LEFT PACK HAD OILY ODOR FOR 5 MINUTES OF OPERATION. RIGHT PACK DID NOT HAVE ANY ODOR. RAN PACKS WITH GROUND AIR CART AND ENGINES IAW 5A1/213, NO FURTHER ODOR FOUND. ALSO RAN ENGINES FOR 30 MINUTES AT POWER SETTINGS WITH NO ODOR FOUND. BLEED LEFT AIR SUPPLY SYSTEM FOUND TO BE INOPERABLE. AIRCRAFT WAS GROUNDED. REACTIVATED THE LEFT AIR CONDITIONING PACK, ACCOMPLISHED A PACK OPS CHECK IAW MM 21-35-00. COMPLETED CARD 05-96-72 AND CARD 05-96-86, FOR DECONTAMINATION CONTROL SYSTEMS.