Leap Testing Leaps Ahead
With initial running of the new Leap-1 engine on schedule in September, CFM International (CFMI) has embarked on an “unprecedented” level of testing that should involve 20 developmental units by the end of next year and seven of the remaining eight planned examples before 2016 (when a final powerplant will take part in a short exercise–possibly a Leap-1C blade-out check).
The equal-share Franco-American joint venture between Snecma and GE Aviation will test an additional 32 compliance examples of the new design, which is expected to take to the air for the first time when a -1C model flies on a flying testbed (FTB) in about six months. FTB work will follow for the -1A in the third quarter of next year and for the -1B in early 2015.
Testing in the past two months has been conducted on the first Leap-1A, the variant destined for the Airbus A320neo and which shares its turbo-machinery with the -1C that will power the Chinese Comac C919. Design of those two models was frozen last year, while that for the remaining -1B variant for the Boeing 737 Max occurred earlier in 2013.
Engine certification and first flight of the -1A and -1C are slated for 2015, with those for the third variant following in the first half of 2016. The new engine is scheduled to enter service as the Leap-1A on the A320neo, ahead of the -1B and -1C versions in 2017 (in that order).
On Schedule or Ahead
CFMI is at pains to relate that, by October, “every major milestone for all three applications has been hit on if not ahead of schedule.” Asked why the Leap-1C will be the first model to fly despite the Comac C919 being the third of the three aircraft to enter service, Chekat Chahrour, GE’s executive vice president at CFMI, said the test schedule is “based on the requirements from the three airplane companies [and] the ultimate entry-into-service [dates]. [We] put the FTB for the -1A first, [but there are] hardware requirements that [must be met] on time [to fulfill the] schedule for each FTB.”
In reality, CFMI will have the hardware for the -1C first: “So we’re just going to go ahead and [fly] it first. This is how we laid [out] our schedule. We like to stick to our plan and not really create ‘churn,’” according to Chahrour.
Nevertheless, the manufacturer expects to apply data from the first flights to subsequent engines. “The -1C and -1A are very similar, although installation is not exactly the same. We’ll get as much useful data as we can out of that [-1C] FTB. But from an engine perspective, everything that we learn on the 1-C is applicable to the -1A.”
Next year, CFMI will finish testing the first engine, said Chahrour. “We’re going to take it down, rebuild it and do an engineering early icing test to make sure we have enough time to react [before certification] if any issue shows up in icing.” The icing test will be conducted in Winnipeg, Canada.
“Then we’re going to do an early block test ahead of certification to give us the practice and the confidence. We [will] run at maximum fan speed, maximum core speed and maximum exhaust-gas temperature for extended periods,” he said. Other 2014 work will include aeromechanics (blade-vibration) tests, rain, hail and ice ingestion, with all the activity repeated on the -1B, for which assembly is beginning in mid-November and which is scheduled to be running in June.
With 20 of the 28 developmental certification engines being involved (according to a notional chart designed to show the depth and breadth of the test and airworthiness approval program), CFMI describes the volume of tests as unprecedented.
The company declines to say how many developmental Leap-1s are assigned to each airframe design: “We are not disclosing how many of each model, because the information can be considered proprietary. Each bar [on the chart] does indicate an engine, but it is a mix of models and missions for the various engines. The length of the bars is indicative of the kind of tests we would do. Some tests can be very short–[such as] fan blade out–[while] others are very long–[such as] endurance or flight test.”
The subsequent 32 compliance units are the flight test engines to be sent to Airbus, Boeing and Comac and that will fly ahead of certification. “So we’ll have 60 engines and we’ll have 40,000 cycles combined on these,” said Chahrour. “That’s equivalent to about 15 years of simulated revenue service. [It’s a] tremendously aggressive and robust program, but this is what it takes to really get into service with the level of reliability that our customers expect from us,” concluded Chahrour.
Commenting on results of about six weeks’ Leap-1A testing, Chahrour said 50 percent power was achieved quickly on the first day of running, with full power being reached a few hours later following a series of required “break-in” runs. “In fact, we achieved above full-rated thrust of the engine–30,000 pounds, well above it, actually–within 48 hours of putting that engine to test.”
By mid-October, CFMI had logged around 175 hours of Leap-1A running, about 170 cycles, and about 165 starts, according to Chahrour. “And I’m proud and really happy to [say it] is running very smoothly. This engine wants to run. The only time that we actually [do] not run it is when we’re trying to change configuration of the engine to meet our test plan objectives.”
The official can scarcely conceal his sense of satisfaction at the results: “Really, everything that we’ve seen meets or exceeds our expectations. We’re very, very thrilled. Everything is working great; the composites (sic) fan blades, the TAPS combustor, the ceramic-matrix composite (CMC) shrouds, and our HPT blades. These are the four newer technologies in the engine and we’re pleased with every aspect of the results.”
Chahrour confirmed that initial testing has been essentially problem-free: “From a mechanical standpoint, the engine is running great (sic), smoothly, and we have had no glitches, no show-stoppers.” Engine starting and operability [are] right on our plan.” The manufacturer has run three different iterations of the core.
This performance is seen by CFMI as a testimony to the module-testing strategy that it introduced four years ago, including the fan, different components and engine-level testing with the fan. “All of that gave us the ‘runway’ to be able to really run smoothly and not interrupt the testing.”
On the question of new technologies, CFMI partner GE Aviation had by mid-October run nearly 1,400 cycles (out of a planned 3,000 cycles) with a set of CMC shrouds on two GEnx engines. “So we’re not relying on the first [test] engine to get [what] we need to know: we have had a pretty generous test plan with the GEnx engine,” according to Chahrour.
As CFMI prepares for the Leap engine’s service entry on three airframes during 2016-17, it faces a steep increase in manufacturing rate. “The goal is to achieve complete production ramp-up within less than three years–from zero to 1,700 engines/year by the end of 2018 [or] beginning of 2019,” said Cedric Goubet (Chahrour’s counterpart as CFMI executive vice president representing Snecma interests). This compares with the partnership’s current annual production of about 1,500 engines.
In September AIN visited the new “pulse line” at CFM’s Villaroche plant south of Paris, where most CFM engines are assembled. It was evident that a real ramp-up in production efficiency has been implemented through a major investment.