What was found
APU FIRE HANDLE RED WARNING LIGHT CAME ON. NO COCKPIT AURAL WARNINGS. DISCHARGED NR 3 APU BOTTLE. CHECKLIST CALLED FOR DISCHARGE NR 2 ENGINE BOTTLE 1 AND BOTTLE 2. ON GROUND APU GROUND FIRE BELL WAS GOING OFF. R & R APU GROUND CONTROL PANEL APU FIRE WARNING BASE ASSY, APU FIRE DETECTION AND HORN CAP AND BULBS IAW AMM 26-21-10-4 AND STANDARD WIRING PRACTICIES MANUAL 20-31-08. ALSO REPLACED NR 2 ENGINE NR 1 AND NR 2 FIRE BOTTLES IAW AMM 26-21-01-4 AND ASSOCIATED SQUIBS IAW AMM 26-21-06-5-4