As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ATB - AFTER T/O SMELLED ACID ODOR, WHICH SEEMED TO DISSIPATE THEN BECAME STRONGER CLIMBING THRU 1100' RETURNED TO AIRPORT. INSPECTED NR 1 AND NR 2 ENG FOR LEAKS. NO LEAKS NOTED. NR 1 ENG WAS JUST CHANGED. INSPECTED BOTH PACKS FOR LEAKS. NO LEAKS NOTED. REPLACED NR 1 PACK COALESCER BAG. HIGH POWER RAN UP CK OK. NO ODOR NOTED.