"FSX," or "Flight Simulator X," is the 10th entry in Microsoft's "Flight Simulator" series. The game is a flight simulator that lets players take on the controls of a range of aircraft, with a variety of viewing options. One of these options is engine view, in which the engines of the craft can be viewed while in flight. There are a couple of simple keyboard shortcuts that can bring up engine view in any craft.
Start or load a game of "Flight Simulator X" with any of the default aircraft.
Hold "Ctrl" and press "Backspace" to trigger a view out the left side of the plane looking at the engine.
Hold "Ctrl" and press "Enter" to look out the right side of the plane toward the engine.
Press "+" to zoom in on the engine, or "-" for a wider view.
Press "W" to return to the view from within the cockpit of your aircraft.
The only craft these commands will not work on is custom-created planes that have not had cameras assigned to the wing-view commands. Official craft released by Microsoft all contain this view. If using an amateur-designed craft without the desired view, contact the craft's designers to see if they can add the camera to a later revision.