What was found
LANDED AT ORD UNDER AMBER ALERT DUE TO A FIRE WARNING IN THE AFT PIT. *S/D* THE CAUSE OF THE INTERMITTENT FIRE ALARM FOR THE AFT CARGO COMPARTMENT WAS DUE TO A DEFECTIVE AFT CARGO SMOKE DETECTOR INSTALLED IN THE NUMBER 2 POSITION. THIS UNIT WAS SUBSEQUENTLY REPLACED BY A NEW UNIT. SINCE THE REPLACEMENT OF THE NEW UNIT, NO FALSE FIRE ALARMS HAVE BEEN GENERATED OR REPORTED. THE REPAIR FACILITY (WALTER KIDDE AEROSPACE) ACCOMPLISHING THE TEST/REPAIR ON UNIT 473108-02 (S/N 1213) FOUND INTERMITTENT ALARM OUTPUT DURING VIBRATION TESTING. THE INTERNAL WIRE HARNESS ASSY WAS FOUND TO BE AT FAULT.