Copyright Simple Flying
Commercial planes are steadily coming equipped with more and more powerful turbofans. These engines produce enormous amounts of thrust, and when they’re cruising at high altitude, they sip fuel with more efficiency than ever before. In the thin, cold air (as low as -60 degrees Celsius) of the high atmospheric layers, modern turbofans perform at their best. The highest airways in the sky are ideal environments for efficient jet engine performance, but they come with their own risks as well. Cold temperatures are still harsh on material, causing brittleness that can lead to stress fractures. High wind speeds and wind shear forces between 30,000 and 40,000 feet produce violent forces that would destroy aircraft were it not for modern engineering quality. One of the most dangerous conditions that a jetliner can encounter at cruising altitude is volcanic ash. Like pouring sand into a running turbine, airborne ash can literally melt an engine. Ice crystals can even form in the air, which creates a hazard to internal engine components. Rolls-Royce describes the phenomenon as “throwing a fist-sized ball of ice” into the engine at hundreds of miles per hour. Thanks to exceptionally high quality standards and incredible engineering, these hazards rarely pose a threat to air travel. The leading turbofan models are routinely 99% reliable in 2025. Now let’s break down just how makers like Rolls-Royce, GE, Pratt & Whitney, Honeywell, and CFM International produce such marvels of modern technology and keep flyers moving around the world. Jet Engines 101 The leading engine makers of today design their powerplants to be optimized for high altitude flying and produce both exceptionally high thrust and very low fuel burn rates. The cold air is ideal for energy savings as the turbines spin, but its thinness makes it difficult to compress. The multi-stage flow of a turbofan engine progressively compresses the air until it is exhausted as forward thrust. A turbofan engine uses what is called the Brayton cycle, a process similar to a super-powered air pump and heater. The process starts with the front fan that draws in a lot of air. Around 80% of that air avoids the core (bypass air) but still contributes to total thrust. After entering the core, the ingested air is compressed by multi-stage compressors, which significantly raise its temperature and pressure. This high-pressure air and fuel are combined in the combustion chamber and ignited, creating a high-energy, fast-moving gas flow. These turbines power the compressors and the main fan by means of a shaft. Ultimately, the hot gas is released through the engine nozzle, producing thrust that drives the aircraft forward by accelerating air backward. Throughout the entire process, the fuel's chemical energy is transformed into kinetic energy in the form of thrust. When the airspeed or direction suddenly changes, as when wind shear strikes, it can cause a compressor stall or surge. To overcome this, there are variable geometry stator vanes inside the engine to stabilize airflow. Pilots have nearly instantaneous throttle control as well, thanks to Full Authority Digital Engine Control (FADEC) systems that rapidly adjust power with digital inputs. Advanced heat-tolerant materials in the turbine’s hot section are used to mitigate the risk of overheating from ash, dust, or sand friction inside the engine. Meanwhile, hot air from the running engine is diverted to heat elements most vulnerable to the effects of ice, like the inlet and guide vanes, to prevent damage. Ice Crystals At Altitude High-altitude ice crystals pose a significant hazard by allowing ice to accumulate inside the engine core, even at temperatures above freezing, eventually leading to engine power loss or flameout. Hot air (bleed air) is directed from the engine's compressor section to heat critical areas, such as the engine inlet, nose cowl, and, sometimes, the inlet guide vanes, to prevent ice formation. Rolls-Royce says these ice crystals enter an engine while still frozen, then quickly melt. When they enter the compressor, the ice crystals refreeze to form a big chunk of ice. When it detaches and gets sucked into the engine, it can cause severe damage to many parts. Critical sensors (pressure and temperature) are heated electrically to ensure they function correctly and provide accurate data to the FADEC and cockpit instruments. Modern engines are put through rigorous testing in specialized icing research facilities like the NASA Glenn Research Center or GLACIER facility run by Rolls-Royce. To maintain stable operation and avoid "core roll back" incidents (thrust loss), ongoing research and development are concentrated on engine control techniques and design that can compensate for the effects of ice crystal icing on engine performance. The Danger Of Volcanic Ash Volcanic ash is highly abrasive and contains silicates that can melt in the hot section of the engine and fuse onto turbine components, leading to engine malfunction or failure. Components in the engine's hot section are made from advanced, heat-resistant materials and coatings designed to withstand high temperatures and resist the adherence of molten ash, which can form glass particles. Sand and volcanic ash are similar in their effects on jet engines. They cause similar damage to aircraft engines as both will melt in an engine. The crucial difference is that, because of their explosive nature, volcanoes blast these particulates to high-flying altitudes. Turbine blades have intricate internal cooling passages and film-cooling holes, which help maintain material integrity. These channels are vulnerable to blockage by glass deposits from ash. Ultimately, the safest course is to avoid ash, but technology has given airliners greater resilience against its effects than ever before. Ongoing research, like that at Rolls-Royce, focuses on improving resistance. The fundamental rotary design of the engine naturally forces some larger ash particles into the bypass flow, away from the core, which can reduce damage to core components to a certain extent. Turbofan Tune Ups Rolls-Royce has established the Engine Environmental Protection team to research and develop solutions to address the most risky dangers to commercial engines. It’s Trent turbofan engine family directly benefits from the technology developed by the group, from sand-resistant thermal barrier coatings to techniques for maintenance to handle exotic contaminants like tree sap infiltration while flying over the Amazon jungle. Data from the FADEC and engine monitoring systems are analyzed to identify any performance anomalies or exceedances during the flight, guiding targeted maintenance actions. Regardless of specific incidents, engines undergo routine inspections based on flight hours and cycles, and complete overhauls at intervals specified by the manufacturer. After exposure to contaminants, an engine is given at least a water wash or a mixture with a solvent to flush out residue from the compressor and turbine sections. Dry scrubbing is avoided as it can scratch components. Then technicians use borescopes to inspect the internal parts, like the compressor and turbine blades, for signs of abrasion or deposit buildup. After an event in which an engine power-loss message or anomaly occurs, regulatory bodies like the FAA mandate specific pre-flight inspections to verify the engine's airworthiness. Icing can affect critical sensors like Total Air Temperature (TAT) probes, so these are checked and de-iced or replaced as necessary. If a large amount of ice has accumulated, the fan and compressor blades are physically inspected and de-iced to ensure free rotation before flight. The Industry Leaders GE Aerospace holds a significant share in the widebody engine market with its powerful engines. The GE90, which powers the Boeing 777, was the first engine to surpass the 100,000-pound thrust benchmark. The GEnx engine on the Boeing 787 Dreamliner and 747-8 is also famous for its power as well as lower fuel consumption and emissions. The remarkable GE9X, known as the largest and most powerful commercial jet engine, has even set a Guinness World Record for thrust at 134,300 pounds. Pratt & Whitney is famed for its innovative Geared Turbofan (GTF) technology. Their standout is the PW1000G GTF engine, which powers the Airbus A320neo, Airbus A220, and Embraer E-Jet E2. The GTF allows the fan and low-pressure turbine to operate at different speeds, resulting in remarkable increases in fuel efficiency and reductions in noise. CFM International, a joint venture between GE Aerospace and Safran, leads the commercial engine market in sales for narrowbody twinjets. Its flagship product, the CFM56, is the best-selling commercial aircraft engine in history. The newer LEAP engine, designed for the Boeing 737 MAX and the Airbus A320neo, builds on that legacy with a technological ”leap” to cement the company's prominence in the market. Rolls-Royce’s RB211 family has been successful in past decades, powering iconic models like the Boeing 747 and 767. The Trent family, particularly the Trent XWB and Trent 1000, dominates the current widebody engine market. Rolls-Royce’s UltraFan demonstrator, which features a new geared architecture, aims to achieve a 25% improvement in fuel efficiency compared to earlier models, foreshadowing a comeback in the narrowbody segment. Twinjet Economics The transition from four-engine jets (quadjets) to twin-engine commercial jets (twinjets) has compelled engine manufacturers to focus on two main design goals: enhanced reliability and improved fuel efficiency. The shift towards twinjets has largely been driven by regulatory changes such as ETOPS (Extended-range Twin-engine Operational Performance Standards), which permit twin-engine aircraft to operate on longer, over-ocean routes. Modern engines feature comprehensive monitoring systems that track engine conditions and oil consumption, enabling proactive maintenance to reduce the risk of inflight shutdowns. Rigorous design quality processes have incorporated field-service lessons from past models to continuously enhance reliability. The economic advantages of fewer engines have led to designs aimed at lowering maintenance costs and fuel consumption. Key advancements include increased bypass ratios, which result in higher fuel efficiency and reduced noise levels. Twinjet engines must produce a thrust-to-weight ratio that compensates for potential engine failure, leading to the development of powerful engines like the GE9X, the largest and most powerful commercial aircraft engine. Advanced features such as Geared Turbofan (GTF) technology and open-rotor designs are driving efficiency in the twinjet market. The demand for highly reliable and powerful engines has spurred engineering innovations that render quadjet designs obsolete for commercial applications.
