As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLT (APU OFF) RED FIRE LIGHT IN APU FIRE HANDLE CAME ON. UPON ENTRY INTO E&E COMP. FOUND AREA EXTREMELY WET. REMOVED APU FIRE DET OPS PWR UNIT, CLEANED AND DRIED AND REINSTALLED. TEST SYS ALL CK GOOD. NO LIGHTS CAME ON REF B727-200 WDM.