How can jet engines operate in rain or snow? Won’t water extinguish the flames inside? How do we remove water from a jet engine in rainy conditions? Does rain or snow intrusion affect the performance of a jet engine?
To address these questions, we first need to understand jet engines. The term “jet engine” is commonly used as a general name for many types of engines, including turbojet engines, turbofan engines, turboprop engines, and straight jet engines.
All jet engines operate by compressing air into a tube.
These engines operate on fundamentally similar principles, but each type has its distinct advantages and disadvantages. All jet engines work by compressing air into a tube, where the air is compressed, mixed with fuel, ignited, and generates thrust.
The key to making a jet engine work is the compression of incoming air. Without compression, the air-fuel mixture will not ignite, and the engine cannot generate any thrust. Most jet engine families use a compressor unit, which includes rotating blades, to slow down incoming air to create high pressure. This compressed air is then fed into the combustion chamber, where it is mixed with fuel and ignited. When the high-pressure gases are exhausted, they are passed through a turbine section consisting of more rotating blades. The combustion gases then continue to expand through a nozzle, generating forward thrust.
Jet engines operate by compressing air.
As mentioned, a jet engine operates by compressing air, mixing it with fuel, igniting that mixture, and expelling high-pressure gases to create thrust. The initial compression process is achieved through a series of rotating blades called a compressor. After the jet fuel is added through a fuel injection system, the mixture is ignited in the combustion chamber. The exhaust gases move through another series of rotating blades known as the power turbine, which powers the engine, and finally through a nozzle.
This is an image of the engine on an A321 after flying through heavy freezing rain.
The greatest danger posed by types of rain such as rain, snow, ice, or fog is engine fire. While rain can affect the functionality of jet engines, it usually does not have significant effects. Most storms produce light rain or snow, or small ice crystals that will not have much impact. In general, only very severe storms affect the operation of engines, and pilots usually take detours to avoid such strong storms.
Most of the rain that hits the jet engine will encounter the blades and slide off. As the blades rotate at an average speed of about 2,000 revolutions per minute, the spinning motion will push most of the water outward like a centrifuge. The small amount of water that remains enters the core will be expelled from the combustor by the compressor blades, while the heat generated from the combustion process will cause the water to evaporate. Additionally, planes tend to avoid thunderstorms due to turbulence.
However, the most challenging forms of rain to deal with are large hail, ice, and freezing rain. Large hail occurs only in very strong storms, which are usually avoided as they cause turbulence during flight, and the impact of hail can also damage the engine or the aircraft’s fuselage.
Freezing rain can be more troublesome, as it forms ice at the engine’s intake or the center of the engine’s rotating shaft. As ice accumulates, chunks of ice can break off and enter the engine, damaging the blades or disrupting airflow and combustion processes. The solution is to establish a heating system that warms the surfaces where ice accumulates the most and prevents its formation. The center parts of some engines are also covered with small rubber components that vibrate when ice starts to form, causing the ice to melt before developing into large and dangerous chunks.
Although rain and snow are generally less hazardous or cause fires during flight, there have been instances where rain and freezing conditions have damaged engines. In August 1987, an Air Europe Boeing 737 had to make an emergency landing in Greece due to rain that caused both engines of the aircraft to experience a fire.
The center parts of some engines are also covered with small rubber components. (Illustrative image).
Just nine months later, in May 1988, a more serious incident occurred when TACA Flight 110 from Belize to New Orleans. This 737 had to fly through a double storm. Heavy rain and hail severely damaged the engine. The crew attempted to restart the engine for a short time, and the pilot had to work hard to make an emergency landing safely.
In 2002, a Garuda Indonesia 737 also experienced a similar engine failure on the island of Java. Similar to previous cases, this flight also had to try to land in a major storm while both engines were experiencing failure. The pilot could not restart the engine or reach the landing site, so the crew attempted to ditch the plane in a nearby river. One flight attendant was killed, and at least a dozen others were severely injured in the accident.
However, the examples above are rare; engine failures due to rainfall are infrequent, and rain rarely threatens the safety of jet engines. A more serious issue that pilots have to worry about is clouds of dust or ash created by volcanic eruptions.
Over 100 incidents involving commercial aircraft encountering these clouds were recorded between the eruption of Mount St. Helens in 1980 and 2006. These clouds can travel hundreds, even thousands of kilometers from the volcano and still cause damage when entering a jet engine. A British Airways Boeing 747 experienced a fire in all four engines while flying through volcanic ash in 1982. It fell from an altitude of 37,000 ft (11,280 m) to 14,000 ft (4,270 m) over the Pacific Ocean before the crew could restart the engines.
