What was found
THE SPONGE-LIKE MATERIAL USED IN THIS TANK BEGAN TO DETERIORATE/DISENTEGRATE. THIS BECAME APPARENT WHEN PILOT BEGAN NOTICING SMALL DARK PARTICLES IN FUEL SAMPLE OF RT INBOARD QUICK DRAIN ON PRE-FLIGHT INSPECTION. PARTICLE QUANTITY INCREASED AND RAN SAMPLE THROUGH A FILTER AND DETERMINED WHAT PARTICLES WERE. UPON REMOVAL, FOUND MOST OF SPONGE MATERIAL LOOSE IN TANK. SUBMITTER FEELS THIS CAME ABOUT AS A RESULT OF AGE ON TANK (24 YEARS) AND 100LL GAS ACTING ON PLASTIC-LIKE SPONGE MATERIAL.