Then and now, come together

A unique meeting: WWII B-17 flight engineer and top turret gunner Frank Girman and EAA B-17 pilot Tom Ewing rotate one of the plane's four engines. The radial engines tended to allow oil to pool in the cylinders, causing catastrophic engine trouble if undetected. So before flight each engine must be turned by hand, seven revolutions. It's not an easy task, and if oil has gotten into a cylinder it becomes impossible until a crewman removes the spark plug and allows the oil to drain.