Amounting to $1.5 million, the cost of a forward outer seal of a Boeing 747 engine is equivalent to four Ferraris.
Jet engines are expensive machines because of the use of novel materials, precise machining, and technologically-advanced systems. A well-researched and robust engine design is essential to withstand extreme forces and temperatures while producing sufficient thrust for flight. Commercial jet engines can cost between $5 million and $50 million, depending on the size and mission requirements.
The use of specialized materials and the requirement for extensive testing determine the cost of a jet engine. Jet engine parts must be manufactured with the highest strength, resilience, and precision. Modern jet engines are manufactured to last thousands of flight cycles before retirement. An engine flight cycle is generally defined as the engine heating to operating temperature, followed by cooling.
Temperature resistant nozzles
Jet engines comprise of specialized materials and technologically advanced systems to achieve the set design requirement. A high-pressure turbine nozzle of a General Electric CF6-80 engine (which powers some Boeing 747s) costs upwards of $2.5 million. The turbine nozzle is a circular machined part with numerous segments that accelerate the airflow to produce thrust. It is made of specialized metals (super alloys) capable of withstanding extreme temperatures.
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The high-pressure turbine nozzle is the hottest component on the GE CF6-80 engine that experiences temperatures of up to 3,000 degrees F (1,700 degrees C). Using expensive temperature-resistant superalloys primarily drives the cost of critical parts. For example, a ton of carbon steel costs approximately $500, whereas a specialized nickel-chromium-based superalloy can cost nearly $50,000 per ton.
Advanced machining techniques
Precise machining and small tolerances further add to the cost of parts. Due to the complex shape of parts (rotor blades in particular), heavy-duty machining techniques such as CNC milling, casting, and electrochemical machining are required. Hard-to-cut titanium and nickel-based alloys require sophisticated metrology and advanced controls for tools, coolants, and machining systems.
While numerous Life Limited Parts (LLPs) on jet engines are replaced at set intervals, most parts and assemblies can be overhauled multiple times to maintain optimal engine performance.
Each high-pressure turbine disk (two stages of turbines on most modern engines) costs between $200,000 and $2 million. An HPT Disk on a narrowbody engine (such as the CFM56) costs approximately $300,000. On larger engines, such as the GE90, a single HPT disk comes with a price tag of over a million dollars.
Use of efficient materials
Large engine manufacturers such as General Electric, Pratt & Whitney, and Rolls-Royce use efficient carbon composites to minimize the engine’s weight. Carbon Fiber Reinforced Plastic (CFRP) is one of several composites that increase the engine components’ strength while keeping their weight to a minimum. Using CFRP has eliminated the need for bulkier fan blades.
Moreover, manufacturers have managed to use fewer fan blades while obtaining greater strength and aerodynamic efficiency of the engine. For example, GE went from having 38 fan blades on the CF6-80 engine to 16 on the GE9X engine. With the fan frame assembly costing millions, each fan blade can cost up to $75,000.
Large air valves that control airflow and regulate pressure can cost several hundred thousand. More minor parts are also costly for customers. Air routing manifolds installed at multiple locations on the engine can cost anywhere between $10,000 and $50,000. While engine operators care less about the individual cost of parts during the engine purchase, each replaced part is charged at its current listing price (or other agreed-upon terms) during a maintenance shop visit.
What are your thoughts on the price tags of some of the critical engine components? Tell us in the comments section.