As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN THE AUXILIARY POWER UNIT FIRE EXTINGUISHER DEPLOYMENT TUBE WAS REMOVED FOR MAINTENANCE, TECHNICIANS FOUND APPROXIMATELY THREE INCHES OF WATER IN THE VERTICALLY MOUNTED TUBE. MINOR CORROSION WAS REMOVED BEFORE REINSTALLING THE TUBE.