What was found
ON CLIMBOUT, FL 28.0 IAS 320 KTS, APU FIRE WARNING LIGHT AND BELL CAME ON. ALSO, ON PILOT'S OVERHEAD PANEL. DISCHARGED APU FIRE BOTTLE, LIGHT WENT OUT IN APPROX 8 SECONDS. ON LANDING, NO EVIDENCE OF FIRE IN APU AREA. WIRES INSPECTED AND FIRE TEST NORMAL PER MM 26-15-00. PLACARDED APU FIRE BOTTLE AND DEFERRED PER MEL 26-8, DUE BOTTLE FIRED.