Expert: Marc Ebelini - 5/3/2004

Question
Why the Jet Engines are located below the wings?
Is there any structural advantage?
(Please answer in Detail.)

Answer
Prime consideration is keeping the top of the wing clean for better lift. Placing the engine on top of the wing would put the thrust above the center line of the aircraft.
Having the thrust below the center line is a compromise.
That's why some aircraft have the engines mounted on the side of the fusilage at the center line. This also aids in relieving in yaw in the event of an engine failure. Keeping thrust as close to the center line both vertically and horizontally makes for good design. Having thrust below the wing pushing up is better than having it above pushing down.
In single prop aircraft, engines were sometime angled down and to the right to offset torgue and produce better climbing angles. Propjet aircraft had engines mounted on top of the wings for prop ground clearance. Again another compromise in design. Any structural advantage would be the ability to drop an engine if the structure failed rather than to have it break into the wing or tail section. I hope this answers your question?