What was found
JFK - FLT 0735 - AFTER TAKEOFF JFK DURING CLIMB-OUT, ACRID BURNING ODOR NOTED THROUGHOUT AIRCRAFT WITH NO OTHER ABNORMAL INDICATIONS. ACCOMPLISHED CHK LIST AND ACFT RETURNED TO JFK LANDING WITHOUT INCIDENT. ACCOMPLISHED BORESCOPE OF NR 1 ENG COMPR, NO DEFECTS FOUND. CHECKED ALL ENG BLEED DUCTS FOR PRESENCE OF OIL WITH NO DEFECTS FOUND. REPLACED ALL COALESCER BAGS AND ACCOMPLISHED GROUND ENG RUN AND PACK BURN-OUT PROCEDURE WITH NO DEFECTS FND. SYSTEM GROUND CHECKED, NORMAL OPERATION. ACCOMPLISHED CHK FLT, PROBLEM REPEATED. REPLACED APU DUE TO OIL DISCOVERED IN BLEED DUCTS. ACCOMPLISHED PACK BURN-OUT PROCEDURE AND REPLACED ALL COALESCER BAGS. SYSTEM GROUND CHK NORMAL OPER. (X)