Core assembly of the first pair of CFM International Leap-1A engines to power the Airbus A320neo is underway, marking the start of a production run that has already amassed firm orders for more than 7,500 engines across all three new-generation variants.

The A320neo flight-test engines are being assembled at General Electric’s production facility in Durham, North Carolina, at the same time as the first Leap-1C for Comac’s C919 is prepared for evaluation on the company’s 747-100 flying testbed in Victorville, California. Ground tests of the Leap-1B variant for the Boeing 737 MAX are also underway following the start of engine runs at Snecma’s Villaroche facility in France last June. The combined activity means the joint GE-Snecma engine development effort is entering its most crucial phase yet.

CFM’s initial market success with the Leap makes it imperative the engine performs as designed from the start, as the A320neo entry-into-service target of mid-2016 leaves almost no schedule margin for performance recovery or post-test modifications. While engine makers are used to pressurized development programs, the sheer number of new Leap engines on order for the growing wave of A320neo and 737 MAX in particular—added to the ambitious guarantees on better fuel burn and the rapid production transition to the new models—takes pressure to a whole new level. The engine competes head-to-head with Pratt & Whitney’s PW1100G for the A320neo market, but is the exclusive powerplant for the 737 MAX and C919.

“We will be certifying the Leap 1A at the engine level in the second quarter of 2015 and then it goes on to power the NEO,” says Gareth Richards, Leap program manager for GE. The first two A320neo units, Nos. 101 and 102, are considered non-standard engines “because they have a lot of instrumentation,” says Richards, who adds that the units will be delivered to the Airbus facility in Toulouse near the end of the year. The Leap-powered A320neo flight-test program is scheduled to run for one year and will be followed by similar-length test phases for the A319neo and A321neo.

The first Leap-1C engine has in the meantime been transported to Victorville where it will be attached to the first of GE’s two 747 flying testbeds with the aim of starting flight tests in early September. The first -1A, which is due to arrive in California about a month later, will be installed on GE’s more recently acquired 747-400 testbed. The two engines will then be tested side-by-side for several months from the fourth quarter onward, marking the first time GE’s flight-test unit has undertaken such an intensive evaluation period.

“We have tripled the staff at Victorville,” says Richards. “We are going from 50 to close to 150 by the time we are finished, and we are at over 100 already. Not only will we have another aircraft, we will be testing the engines in parallel, so they are actually going to operate together. We will have two flight-test crews and two teams of mechanics operating three shifts, seven days a week.” The special test pylon, which attaches the Leap-1C to the 747, was delivered by Comac at the end of 2013 and has been configured with test wiring and is “ready to go,” he adds.

CFM expects to deliver the first flight-compliance engines to Comac in the second quarter of 2015. The revised schedule now calls for certification of the C919 to be completed by late 2017, with entry into service set for early 2018. The Chinese manufacturer revealed in early 2013 that it was extending the development schedule for the 158-seat airliner; at that time it expected to delay first flight from mid-2014 to mid-2015. “Comac’s first aircraft is in assembly. We have seen it and it is coming along very well,” says Richards.

Despite the schedule change at Comac last year, CFM opted to adhere to its original test plan because of the similarities between the engines for the C919 and the A320neo. “Other than the externals and mounting, the turbomachinery and part numbers are common. Whatever we learn from the performance and operability of the -1C will be applicable to the -1A. The control software adjustment for the -1A will be based on the -1C experience, so we don’t see it as the -1C first and the -1A second. We see it as two flight tests of basically the same engine,” Richards says.

The Leap-1C will be the first CFM engine to be supplied with a new-generation nacelle, and that factored into test-program planning. The nacelle was developed by Nexcelle, a joint venture between Safran subsidiary Aircelle and GE Aviation’s Middle River Aircraft Systems. 

The nacelle configuration incorporates a one-piece composite O-Duct which replaces the conventional two-piece “D” doors in a standard thrust-reverser arrangement. When deployed, the O-Duct moves aft to the reverse-thrust position, eliminating drag links in the engine’s secondary flow path and increasing the efficiency of the reverser.

The Leap-1A following closely behind is a dedicated flying testbed engine with externals and structural modifications to enable it to fit onto the 747-400. “That aircraft is in Victorville and has finished its modification and is also going to go through the same sequence. The pylon needs to be installed; the key difference is that it has Airbus systems. We are providing the pylon and Aircelle is providing the nacelle.” For the initial test-campaign units, Aircelle has contracted the work back to GE Middle River. “Officially, it is still an Airbus nacelle,” he adds.

While the upcoming flying testbed work is “a highly visible part of the program, it is not a difficult test from an engineering point of view,” says Richards. “It is all about calibration and performance. What’s important to certification is everything else such as the [150 hour] block test, the icing test, fan blade out, ingestion, hail, rain, IMI [maintenance intervals] and extended range operations. Those will make the difference in when and how well we complete certification,” Richards adds.

The Leap-1A flight-test engine is the sixth overall in the test program. The first five include four -1A/Cs and the first -1B. The engine for the 737 MAX is scheduled for certification in the first quarter of 2016, roughly concurrent with the start of flight tests.   

“We are in the final stages of build of the next –1B engine, which goes to test in the September-October period. The first engine is not a certification engine,” Richards notes.   

He expounds, “It will be used for all sorts of engineering tests, just like the first -1A engine which is now on its third build. We will do practice ingestion tests, early icing, bird shots and so on. The first -1B has a similar engineering mission and we will be exercising the heck out of it.”  


Podcast Senior Propulsion Editor Guy Norris discusses the challenges facing engine makers in our latest Check 6 podcast.