As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRE-UNIT, S/N 0274, AIRCRAFT UTILIZE - .020 INCH SKIN FILLED WITH FOAM FOR RIGIDITY IN THE CONSTRUCTION OF THE VENTRAL FIN. THE FOAM ALLOWS MOISTURE TO COLLECT AND CORROSION TO DEVELOP ON THE INSIDE SURFACES OF THE SKINS. POST-UNIT, S/N 0274, DELETES THE FOAM.