As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EXPERIENCED VISIBLE SMOKE/FUME FOLLOWED BY A SMOKE TOILET CAUTION MESSAGE AFTER TRANSFERRING ENGINE BLEEDS TO APU ON APPROACH INTO BWI. RAN ENGINE WITH APU WITH PACKS ON UNABLE TO DUPLICATE PROBLEM AT THIS TIME. INSPECTED LAVATORY SPEED TAPE AND FOUND TO BE IN GOOD CONDITION IAW AMM 05-50-00. AIRCRAFT OK FOR SERVICE.