How aircraft engine cleaning means more efficient flying

Flying accounts for the vast majority of an airline’s carbon emissions, with most of these emissions resulting from fuel consumption during flight. Improving fuel efficiency, therefore, plays an important role in addressing aviation’s environmental impact.

How cleaning helps improve fuel efficiency

One way airlines can do this is by keeping aircraft engines clean. The cleaner the engine, the more fuel efficient it is. That is why airlines, including Cathay Pacific, wash their engines regularly to remove deposits from the engine core, where combustion takes place.

The core sits behind the fan blades visible from the front of the engine. Here, some of the air drawn in by the fan is compressed before being mixed with fuel and ignited. This combustion drives the turbines, which in turn power the large fan at the front of the engine.

“Regular engine washing helps to maintain efficiency and delivers optimal fuel performance,” says John Brownen, Cathay Pacific’s Head of Technical Services. As engines work for long periods under pressure and at high temperatures, deposits can accumulate in the core, reducing efficiency.

From traditional water washing to a new modernised treatment

Traditionally, engine washing involves pumping 300 to 400 litres of hot water through the engine intake. A shroud and collection system fitted to the rear of the engine captures the residue, which is filtered so the water can be reused. The process is repeated two to three times before the engine is left to cool and dry, preventing moisture from entering the cabin air system, which also draws air from the engine.

Some aircraft in the Cathay Pacific fleet are now receiving the Rolls-Royce treatment through a newer washing process developed by the engine manufacturer. Rather than using water, specialised equipment injects a fine detergent mist through the engine intake. A vacuum attached to the exhaust draws the mist through the engine core, and is powerful enough to rotate the turbine shaft, ensuring an even distribution throughout the engine.

The result is a faster, more efficient process that requires less maintenance intervention, such as opening engine cowls for access. It also eliminates drying time and uses significantly less water. As a result, engines can be washed more frequently, which brings substantial benefits.

Brownen says, “Across all engine washes over a season, we estimate the process contributes to a reduction of about 5,700 tonnes of carbon emissions – that’s equivalent to the emissions from about 18,000 passengers flying a round trip between Hong Kong and Seoul.”