Safran Nacelles’ innovation goes airborne in the COMAC C919 jetliner’s first flight

May 17, 2017

With the touchdown that concluded its maiden flight earlier this month, COMAC’s C919 relied on the capabilities of Safran Nacelles’ innovative O-Duct thrust reverser – which brings new levels of efficiency, lower weight and easier maintainability for nacelle systems on jet-powered aircraft.

The C919 flew for the first time on May 5 from COMAC’s final assembly site at Shanghai Pudong International Airport, deploying the O-Duct thrust reverser to decelerate this Chinese-built airliner during its initial landing rollout.

Safran Nacelles’ O-Duct thrust reverser is among the company’s contributions to the C919 nacelle system supplied by Nexcelle – a joint venture of Safran Nacelles and GE Aviation’s Middle River Aircraft Systems. The thrust reverser’s designation comes from its O-shaped duct configuration when viewed from the front.

Safran Nacelles evolved the O-Duct concept based on its expertise as one of the world’s leading aircraft nacelle system suppliers. The O-Duct represents a significant step forward in simplifying the design and reducing the interfaces of thrust reversers, which are used to reduce an aircraft’s speed of during landing.

A commitment to nacelle systems innovation

“Bringing the O-Duct thrust reverser to reality demonstrates how Safran Nacelles’ delivers innovation for the benefit of aircraft manufacturers and operators,” said Safran Nacelles CEO Jean-Paul Alary. “It results from decades of experience and dedicated work by our expert teams, who are committed to making nacelle systems lighter, quieter, smarter and easier to maintain.”

The O-Duct is a single-piece unit produced with lightweight composite materials, and replaces the two-piece “D” doors on traditional jet engine thrust reversers.  When deployed, the O-Duct enhances the airflow path while also increasing thrust reverser efficiency.

An electrical thrust reverser actuation system (ETRAS) is used to operate the O-Duct, replacing heavier hydraulics in other thrust reverser designs. The ETRAS’ utilization on C919 follows Safran Nacelles’ pioneering application of an electrical thrust reverser actuation system for the Airbus A380, which has been in airline service since 2007.

Nacelle design with maintainability in mind

Airlines operating the C919 will benefit from facilitated maintenance that comes from multiple aspects of the engine nacelle design.

The O-Duct thrust reverser is attached to the pylon, providing the advantage of being an independent fixed structure that is replaceable directly under the aircraft’s wing in the manner of a line replaceable unit (LRU). This architecture ensures the thrust reverser can be quickly replaced if damaged, avoiding the need to change out the thrust reverser actuation system as well.

By designing the thrust reverser with ETRAS for electrical actuation, the O-Duct has been simplified when compared to hydraulic technology, and corrosive fluids are eliminated.

Cooperation for an integrated propulsion system

The overall C919 nacelle system is supplied by the Nexcelle joint venture to equip the jetliner’s LEAP-1C turbofan engines from CFM International, which itself is a 50/50 joint venture of GE Aviation and Safran Aircraft Engines.

Nexcelle’s close collaboration with CFM International on the LEAP-1C has resulted in one of the first truly integrated propulsion systems for the air transport sector.