What was found
FIRE CARGO FWD MSG ON UPPER EICAS ON FINAL APPROACH. FWD CARGO FIRE BOTTLES WERE DISCHARGED ON ARRIVAL. A CHECK OF THE FORWARD CARGO PIT AFTER LANDING REVEALED NO EVIDENCE OF A FIRE. THE SMOKE DETECTORS WERE COVERED WITH MOISTURE. THIS IS CONSISTENT WITH SIMILAR EVENT ON UNITED 747-400 AIRCRAFT IN THE PAST. IT SUGGESTS THE CARGO WAS PROBABLY SOME SORT OF PRODUCE THAT HAD NOT BEEN PROPERLY WRAPPED TO CONTAIN ITS MOISTURE. FALSE FIRE WARNINGS DUE TO MOISTURE IN THE CARGO PIT ARE A LIMITATION OF BOEING'S SMOKE DETECTION SYSTEM DESIGN.