Engine Foam Wash Prevents Damage and Reduces Fuel Burn

Jet engines degrade in normal operating conditions compared with new deliveries. Challenging environments accelerate the degradation of parts and, with this, fuel efficiency.

In the Middle East, for instance, fine dust particles are especially hard on engines. But degradation also occurs in “normal” environments, as well as super-cold ones.

Volcanic ash can cause catastrophic failure, such as with the 1982 incident in which a British Airways Boeing 747 with Rolls-Royce engines flew unknowingly at night into a high-altitude ash cloud. All four engines shut down due to ash ingestion and significant damage.

The crew was finally able to restart the engines as the jumbo jet glided toward what seemed like a certain water ditching. The plane made a safe emergency landing.

Dust doesn’t have remotely the same effect. Its degradation to the engine occurs over time.

These issues have prompted GE Aerospace to develop a new foam engine power wash that cleanses the engine. The company presented the technology to reporters in a media briefing on May 19.

For an Airbus A320neo airliner with a CFM International Leap-1A engine, the wash takes about four hours. Typical intervals for an active maintenance program are about every 250 to 500 cycles. Widebody engines take longer, at about eight hours.

The foam wash replaces a water washing process that’s been around for decades. Pratt & Whitney introduced its water wash system in the early 1980s to clean JT8D engines used by Muse Air Corp’s McDonnell Douglas DC-9-50s and MD-80s.

GE’s foam system is currently used on only five commercial airliner engines: the CF34, Leap, GE90, GEnx, and the Engine Alliance GP7200 made by GE and PW. The science may be applied to smaller engines used on business jets.

Better Than Water Alone

The foam technology, which replaces a conventional water wash, uses two J-hooks at the front of the engine to spin the fan. This ensures that cleaning extends through to the aft stage of the compressor or the hot section. These sections need cleaning to restore the asset’s operational integrity.

GE’s foam is a specific chemistry that dissolves dust. It’s compatible with GE’s engine materials. The foam is injected into the aft stage of the compressor and systematically through borescope ports to remove debris that's built up there. The debris degrades the efficiency of that compressor over time.

GE wants to do this type of cleaning at the same time as other prescribed maintenance, so there’s no impact on the engine's utilization for the airline. The wash may occur with the engine on the wing.

Called 360 Foam Wash, the wash process leads to improved fuel economy from the engine’s degraded point, according to GE. An engine that’s running colder lasts longer, and it uses less fuel. It also extends the lifespan of key parts, improving durability.

Foam Wash has been licensed to more than 10 customers, including those in the Middle East and North America. SkyWest Airlines, which operates a fleet of Mitsubishi CRJs and Embraer E1s with the CF34, is one example. The same process could work for turbofans powering business jets.