GE Aviation is preparing to begin flight tests of its new Leap-1C and Passport engines featuring nacelles developed for them by the group’s Nexcelle joint venture with Safran subsidiary Aircelle. Last month, Nexcelle delivered the first full new-generation nacelles for both programs. They are due to fly soon on the engine maker’s Boeing 787 testbed. The Leap-1C is to power Comac’s C919 narrowbody airliner, while the Passport has been selected for Bombardier’s Global 7000 and 8000 business jets.
According to Nexcelle president Michel Abella, the primary goal for the integrated approach to designing the nacelles is to lower operators’s direct operating costs by contributing to improved performance of the engines and delivering improved reliability. For instance, overall installed weight has been reduced through using new pylon designs. He told AIN that significant improvements have been achieved by designing the nacelles under the concept of the integrated propulsion system (IPS) in closer engineering cooperation with those working on the rest of the powerplant, including the pylons and mounts.
Nexcelle’s Panache thrust reverser for the Leap-1C IPS features the company’s new O-Duct design, which replaces two D-shaped doors in a traditional reverser. The O-Duct design is more efficient due to the removal of the links that cut the reverser’s flow path in two with the D-shaped doors.
In the Panache unit, the thrust-blocking doors are located around the full inner circumference of the composite O-Duct structure. They are deployed by new mechanisms attached to the forward frame and are fully contained inside the O-Duct structure when stowed, avoiding any interference with fan flow.
The Panache system is on display here at Farnborough this week on the Safran exhibit (Hall 4 Stand B12). It also features a new castellated ring interface between the thrust reverser and the engine, which are connected via the A2 flange. When the ring is rotated, the entire O-Duct moves on pylon-mounted tracks and sliders, opening up access to the reverser’s inner fixed structure for maintenance. The IPS for the Passport engine has a similar design philosophy but it does not feature the Panache thrust reverser.
“One of the good things about the O-Duct is that it is all one piece, which reduces the number of seals inside it and also cuts the aerodynamic losses that you get with a normal thrust reverser,” said Abella.
Under the joint venture, GE’s Middle River Aircraft Systems subsidiary is responsible for the inlet and fan cowl for both the Leap-1C and the Passport. It also makes the engine mounts and inner fixed structures for the Leap engine. Aircelle has developed the thrust reversers for both turbofans, as well as the inner fixed structure for the Leap. The Leap IPS features an electrical thrust reverser actuation system, which is a new approach introduced by Aircelle for the A380.
With flight-testing about to get under way to enable the two new nacelles to enter service around 2017 and 2018, Nexcelle is putting plans in place for product support. The company is also getting ready for the anticipated production ramp up in support of the C919 and Global programs.