What was found
APU FIRE MESSAGE AND BELL CAME ON AFTER STARTING NR 2 ENGINE. NO FIRE OR ABNORMAL TEMPERATURE. TRIED POWERING DOWN EVERYTHING AND RESET BUT FIRE MESSAGE AND BELL STILL ON WHEN POWER WAS ON. POWERED ACFT AND CHECKED EICAS. NO MESSAGE. CHECKED APU SENSING ELEMENTS AND FOUND A PORTION OF THE SENSING ELEMENT SLIGHTLY TOUCHING THE AIRFRAME. REPOSITIONED SENSING ELEMENT AND PERFORMED APU FIRE DETECT OPS TEST. OPS CHECKED GOOD IAW MM 26-10-25. PERFORMED 2 ENGINE STARTS WITH APU POWER. NO CAS MESSAGES. OPS CHECKED GOOD.