in the C-Hog its the coolent line that flushes the outter heat sink of the 4 gauss rifles
In the Nik, its a pressure guage line used by the dial to check the internal pressure of the Nik's turbofan engine.
In the B-17 there are several, they are just strings that are tied to the gunners noodlees, whenever the plane gets pinged the pilot yanks the strings to "motivate" the gunners SA
In the Lancaster they are oxygen lines for the crew to use when to bomber passes into low earth orbit.
more to come as I think of them.....