What was found
ETOPS SIGNIFICANT SYS, RETURNED TO FIELD DUE TO SMOKE ODOR AND LAVATORY ALARMS GOING OFF FOR SEVERAL MINS. REPLACED HEPA FILTERS IAW 21-25-02-INSPECTED LT & RT PACK HEAT EXCHANGERS FOR OIL FOUND TO BE DRY. DUCTS LEFT OPEN IAW FURTHER TROUBLESHOOTING IAW AMM 21-51-02. R & R TWO HEPA FILTERS IAW AMM 21-25-02. ACCOMPLISHED ENGINE POWER RUN WITH BOTH PACKS OPERATING 85 DEG, PSID 8. ALL CHECKED GOOD. REPLACED LAVATORY SMOKE DETECTORS IN POSITIONS E, F, G, H, IAW AMM TASK 26-13-01. ALL TESTED GOOD. REMOVED LT PRIMARY AND SECONDARY LT HEAT EXCHANGER AND PLENUM ASSY IAW AMM 21-51-02-004-001. INSTALLED REPLACEMENT PRIMARY AND SECONDARY HEAT EXCHANGERS IAW AMM 21-51-02-404 019. REPLACED LT & RT ACFT WATER EXTRACTORS IAW AMM 21-51-04-015. INSTALLATION TEST ACCOMPLISHED, LEAK CHECKED GOOD. SYS OPERATES NORMALLY.