What was found
DURING ACCEPTANCE CHECK WITH APU RUNNING, HEARD LOUD BANG FROM REAR OF ACFT. ON WALKAROUND, F/O NOTICED FIRE COMING FROM APU COMPARTMENT. APU FIRE PUSH LIGHTS SELECTED AND FIRE EXTINGUISHED. NO APU FIRE LIGHTS ILLUMINATED. C/W IMMEDIATE ACTION CHECKLIST. REMOVED AND REPLACED APU AND APU GENERATOR IAW AMM, OPS CHECK GOOD, REMOVED FROM MEL. (K)