United Airlines signed a multi-year agreement with Pratt & Whitney to use the EcoPower engine wash system on its entire fleet of engines by the fall. This will cover 360 aircraft after United retires its Boeing 737 fleet and four 747s. United plans to save 3 million gallons of fuel annually from washing its powerplants.

United plans to start offering the EcoPower engine wash service at San Francisco, Los Angeles, and Washington, D.C. (Dulles) to its third-party customers once the service is operational. The agreement calls for United to do some of the washes and Pratt & Whitney to perform others.

United did not disclose financial terms of the agreement.

Southwest Airlines hopes to save $20 million in fuel costs annually by washing its CFM56-7B engines. The airline started cleaning the engines, which power its Boeing 737-700s, in April with Pratt & Whitney's EcoPower engine wash system. Southwest's EcoPower contract spans three years.

Southwest's engines are getting washed at Pratt & Whitney's service centers in Oakland, Calif., and Orlando, Fla. The Oakland facility plans to wash four engines per night. Depending on the engine, they each can get washed multiple times. For instance, a recent Southwest engine that had been on-wing for 10 years needed five washes to reduce the particulate.

EcoPower sprays water into the core of the aircraft engine and collects water and contaminants. The closed-loop system takes 60 to 90 minutes and costs between $3,000 and $5,000 per wash at list prices. Pratt & Whitney recommends washing engines twice year, depending on the operating environment in which they fly.