Case Study: Apache Helicopter Primary Exhausts

Exhaust Venting Ducts Which Mask the Engines' Heat Signature

Primary Exhausts for Apache Helicopters.


  • Design Angles to Conceal Engine Heat
  • Built to Tolerate Extremes in Battleground Conditions
  • Weld Strengths Withstand Extreme Exhaust Heat, Vibration, Aging
  • Switched from Stainless to Inconel for Higher Temperature Tolerance
  • Proudly Made by ACE for More Than 35 years

The Apache is heavily relied upon by the armed services, and is frequently in the harshest military operating environments imaginable. One of the significant defenses it has is the way it hides its heat signature from infrared sensors. The Primary exhausts, manufactured by ACE, have three channels which bend, obscuring a direct visibility of the engines. The Secondary exhausts that the Primaries fit inside of wrap them in thick, thermal insulation, protecting the vehicle from detection.

The six sides and base components for each of these Primaries are formed from severe-heat resistant Inconel, an austenitic nickel-chromium based super alloy. This metal is also oxidation and corrosion resistant, making it ideal for extreme environments. The shapes are formed from sheets on ACE’s drop hammers, trimmed on our 5-axis laser cutter and transported to our assembly and welding departments. There, the elements are secured by fixtures, which hold the shapes in precise alignment for welding. Our deburring team then grinds-out any remaining imperfections to a smooth surface to meet strict customer requirements. Once thoroughly inspected, delivered and installed, the Primary’s unique and complex construction resists wear-and-tear from extreme heat and vibration from the Apache’s turboshaft engines.


    • The process begins with this die and a hydraulic press. Sheets of Inconel are formed on this shape with controlled pressure.
    • 10 tons of pressure provide this complex, convex shape, one of six different side panels.
    • Elements are then trimmed on our computer-programmed laser cutter. This laser cutter is precise, and can trim 20 forms in the same time it takes to trim one using traditional methods.