What was found
ABE- PIT FLIGHT 3511 CREW REPORTED WHILE ON DESCENT THROUGH 8000 FT UNKNOWN SMELL WAS NOTICED IN COCKPIT AND CABIN. SMELL WAS SUSPECTED TO BE SMOKE COMING FROM NR 1 ENGINE BLEED. EMERGENCY WAS DECLARED, AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED APU AND SURROUNDING AREA. NO DEFECTS WERE NOTED. ENGINE OILS WERE CHECKED, AND RIGHT ENGINE FOUND TO BE 3 QUARTS LOW, LEFT ENGINE 1 QUART LOW. OIL WAS SERVICED. AIRCRAFT GROUND RAN FOR 20 MINUTES WITH BLEEDS ON. NO DEFECTS WERE NOTED. AIRCRAFT RETURNED TO SERVICE.