In a recent email, a pilot related a problem he had with his aircraft: He needed to drain the fuel tanks so that he could repair the wing.
He drained the 100LL out of the tanks into two plastic drums. The fuel sat in his hangar for several weeks and then outside in the sun for several more.
When the repairs were done, he started to return the fuel to the aircraft and noticed that in one drum the fuel color had changed from blue to tan. He tried the other drum and it was still blue. But when he got down to the last few gallons, that fuel was also tan.
He drained the last few gallons through a filter, and it left a tan coating on the filter.
He asked what happened and what should he do. [Read more…]