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Cessna’s T-37 was dubbed “Tweety Bird” for its shrill Teledyne CAE J-69s. (USAF)

The Little Engine That Couldn't

The new Eclipse 500 lightjet will no doubt make a lot of customers happy

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(Continued from page 3)

The decision to abandon the simple, well-proven two-shaft configuration of all previous Williams fanjets set off controversy within the company. “Some of the guys who’d worked on the FJ44 didn’t have much confidence in the EJ22,” says Lays, who explains that one impetus for the three-shaft design came from Sam Williams’ son Gregg, then a Williams VP and now company president, who’d spent two years working with Rolls-Royce on the RB.211. “Gregg was hooked on three-spool engines back then,” Lays recalls.

The axial high-pressure compressor showcased at Oshkosh was also a departure for Williams, which had used centrifugal compressors in all its previous engines (see “Compressors,” p. 23). Other rumored design features-—compact in-line combustors, tiny integral accessories mounted directly on the main shaft—will not be revealed until next year, when a five-year NASA embargo on the release of FJX-2 technical publications expires.

The key to the FJX-2’s extraordinarily light weight was its manufacturing technology. Williams, with decades of experience building jewel-like cruise missile engines, is unrivalled in its ability to craft tiny, durable jet engine parts with great precision. Burkardt quotes one of the losing bidders for the GAP program at the Oshkosh show where Williams exhibited its tiny compressor. “The guy told me, ‘Now I know why you chose them instead of us,’ ” Burkardt recalls. “No other company could build this engine.”

But could Williams get it certified? While the FJX-2 merely had to produce thrust in a test cell, the EJ22 would have to pass a battery of FAA tests to prove that it could start reliably, run without a hiccup for thousands of hours, supply bleed air for pressurization and de-icing, run a generator, be easy to service and repair, and survive the real-world ingestion of gravel, ice, and birds. (Birds do not scale down either; an EJ22 swallowing an FAA-mandated four-pound bird is the equivalent of a Boeing 777 engine ingesting a small cow.)

While Williams wrestled with these challenges, Eclipse began building the first test airframes. By the summer of 2002, the airframe of N500EA was ready to go. Williams, although behind schedule, was reporting good progress with the engine development. So it was with keen anticipation that some 50 Eclipse employees gathered in the 2 a.m. darkness to welcome a Falcon jet freighter as it pulled up to the Eclipse hangar. The first EJ22 was off-loaded, uncrated, and gently set down on the hangar floor. “It was pretty and new and shiny, and everybody just sat there stroking it,” recalls Raburn. “It was fantastic.”

The euphoria died, however, when the engine refused to start. It took an impromptu mixture adjustment, over the objections of Williams engineers, to get it going. And that was just the beginning. The starters overheated and failed. Seals leaked. Shrouds cracked. Fan blades broke. The fuel controller had problems. Serious snags bedeviled the integration of the engines to the airframe. “Within a few days we realized that the engine was massively immature,” recalls Raburn.

To make matters even worse, the EJ22 had not been designed to be repairable or serviceable in the field. “We had to ship engines back to Williams 15 or 20 times in the first 90 days,” says Raburn. “The air freight company ended up just basing their plane here. The pilots told us, ‘We’re not flying back home, because we know you’re going to need us again in a few days.’ ”

After about six weeks, Eclipse managed to get two engines running at the same time. (Still, one wouldn’t start for the official rollout ceremony, so the airplane had to be towed out of its hangar to meet the aviation press.) Eclipse discovered that at high power settings, the EJ22s ran hot and could not achieve their expected thrust without exceeding inter-stage turbine temperature limits. On that anemic first takeoff, it was the combination of those temperature limits and density altitude that reduced the engine thrust to barely half the nominal 770 pounds.

Disillusioned with Williams, Eclipse brought in an outside consultant, who concluded that the engine was, at best, still two or three years away from certification. Eclipse had neither the time nor the money for such an extended effort. “The core problem was that the EJ22 was radically more complex than anything Williams had ever done before,” says Raburn. “It was so tiny and so complex that we came to believe it could never be robust enough to operate the way our customers were going to operate it. It’s got to be a bulletproof engine that just runs and runs and runs. The EJ22 was never going to do that. It was like a Ferrari V-12 in a New York City bus.”

After being dropped by Eclipse, the EJ22 quickly disappeared from public view. Williams removed all mention of it from the company Web site, and halted efforts to have it certified. “There’s no airplane out there for it,” explains Sam Williams in an odd reversal of the bold “If you build it they will come” philosophy that drove the company to dominate the cruise missile and light business jet marketplace.

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