Just noticed this tonight, but when I tried to fire up my B-17's and switched to F3 view, the engines would restart their start-up cycle. I experimented on a number of planes offline and got the same result, so this is found throughout the planeset. FYI, it takes 9 seconds for the engines to crank up, turn over, and begin propelling the plane forward. As long as I kept toggling between view modes before the engines finished turning over, I could make the engines restart themselves for over a minute.
This only occured from the initial spawn point on the runway. If I cranked up, moved forward, killed the engines and tried to repeat the process the bug would not occur.