Pratt & Whitney (P&W) is considering a design change as the first PurePower PW1100G engine for the Airbus A320neo family completes ground testing, company officials say.
The reduction gear-equipped PW1100G is designed with a variable area fan nozzle, but P&W is studying whether it should be removed, says Bob Saia, vice-president of the next generation product family at P&W, at a press event in West Palm Beach on 11 April.
Removing the part "makes the engine lighter and less complex", says Saia. At the same time, P&W originally believed that the nozzle would be an essential feature for a low-speed inlet fan, which is enabled by the unique reduction gear system installed in the PurePower engine series.
P&W discovered last year that a similar nozzle designed for the PW1500G, which powers the Bombardier CSeries, was not needed, so the complex, moving part was discarded.
As the PW1100G is prepared to enter flight tests in next "four to five weeks", Saia says, P&W engineers are applying the same scrutiny to its variable nozzle system.
The component extends the area of the exit nozzle for the fan by up to 10% in high-speed cruise mode. That change is intended to smooth any airflow disturbances caused by the low pressure of PurePower's slower-moving inlet fan.
So far, P&W has only tested a fixed exit nozzle on the first two PW1100G engines during ground tests. The nozzle is extended and retracted manually to simulate either take-off or cruise conditions, Saia says. The first automatically-moving variable area fan nozzle will not arrive until the delivery of the sixth or seventh PW1100G test engine, he adds.
P&W has accumulated 120h of ground testing on the first engine and about 20h of testing on the second PW1100G. Flight tests will begin next month aboard the P&W Boeing 747SP flying test bed, which is based in Montreal, Canada.
The engine is scheduled to be certificated a year later, and then enter a flight test campaign to achieve the airworthiness certification for the A320neo in 2015.