The nearby University where my father worked as I was growing up had a DC-3 (civilian liner) and a C-47(military cargo). My dad flew lots of missions in the back of the C-47 developing an infrared thermal imaging system for the CIA. They eventually switch over to an Aero Commander for that duty because the C-47 was a fuel glutton. The DC-3 was lost to an accident. The pilot was a friend of ours and was the pilot who flew my dad in the C-47. He was the most conscientious and safety-conscious pilot I ever flew with. He was taking a cross-country flight in the DC-3 and stopped in a little airport for Avgas. After takeoff the plane made it up a couple of hundred feet and the engines conked out. It crashed into a forest killing all aboard.
It turned out that the fuel distributor put a new kid on the fueling job. Rather than Avgas he pumped in jet fuel. Charlie, the pilot, did his fuel drain test into a cup but saw no jet fuel because it floated above the gas in the tank. Sad.
Bob