As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR RETURN FOR LAV SMOKE INDICATION. MAINTENANCE COMPLIED WITH A VISUAL CHECK, BOROSCOPE BOTH ENGINES AND TEST FLEW TO CLE AND NO FURTHER ISSUES WERE NOTED. TEST FLIGHT GOOD. RELEASED BACK TO SERVICE. RESULTS OF THE ENGINE TEARDOWN REVEALED LEAKAGE FROM THE COOL FRONT SUMP.