How Boeing Shortens Engine Exhaust Fairings to Save Weight

A design for aircraft engine exhaust systems that allows the protective fairing behind the engine to be shorter, reducing weight and drag.

What it covers

This patent describes a way to shorten the aft strut fairing—the aerodynamic cover that sits behind the jet engine on an aircraft wing. By precisely aligning the heat shield so it ends exactly where the engine's exhaust nozzle ends, the design eliminates the need for extra shielding further back. It uses specific pressure regions (1.3 Pbar vs 0.85-1.2 Pbar) at the nozzle outlet to create an aerodynamic barrier, preventing hot engine exhaust from flowing into the gap between the engine and the fairing. This allows the fairing to be physically shorter without risking heat damage to the aircraft structure.

What it doesn't cover

• —Does not cover exhaust systems where the heat shield extends downstream past the nozzle trailing edge.
• —Does not cover fairings that include heat shielding on the surface located downstream from the nozzle outlet.
• —Does not cover engine designs that do not utilize the specific pressure differential described to prevent exhaust flow into the fairing gap.

The clever bit

Instead of using more physical material to shield the fairing from heat, the design uses the engine's own exhaust pressure profile to create an invisible aerodynamic wall that keeps hot gas away from the structure.

Why it matters

In commercial aviation, every pound of weight reduction translates directly into fuel savings and increased payload capacity. By shortening the aft strut fairing, Boeing can reduce the overall drag and weight of the engine pylon assembly, which is critical for the efficiency of modern high-bypass turbofan engines.

Real-world examples

• 1.Modern Boeing commercial aircraft engine pylon assemblies
• 2.High-bypass turbofan engine exhaust configurations