The Legacy 500, the world's first fly-by-wire super-midsize business aircraft, was expected to have completed its first flight by early this month, triggering an exuberant, but very brief celebration at Embraer's headquarters in Brazil. The aircraft was slated for certification in 2012, but that original development schedule assumed first flight in third or fourth quarter 2011. That target day passed because Parker Aerospace, supplier of the three-axis fly-by-wire (FBW) control system, failed to earn a critical software approval, thereby grounding the flight test program for a year or more.

Parker's problems were traced to improper software documentation for the remote electronic units (REUs), the computers that command movement of the flight control actuators. Demonstrating strict FBW software verification and validation to airworthiness authorities is as critical to safety of flight as showing that you've used only aircraft grade hardware for the flight control computers and flight control surface actuators. Software glitches potentially can have fatal consequences, so ground testing of the aircraft at São José dos Campos has been limited to 80 kt., well below liftoff speed at the lightest weights.

Upon learning of the depth of Parker's problems, Embraer was compelled to send in its own team of software engineers and also an expert crew from veteran FBW firm BAE Systems. Ultimately, the aircraft manufacturer transferred responsibility for FBW software development from Parker to BAE Systems, with Parker's Irvine, Calif., division supplying hardware components.

Parker's woes doubtlessly blindsided the Brazilians because the California firm supplies key FBW components for the latter's ERJ 170/190 regional airliners. But the Legacy 500's three-axis FBW is considerably more capable and more complex than the two-axis digital electronic controls installed on Embraer's E-Jets.

Fortunately for Embraer, BAE Systems is intimately familiar with the overall Legacy 500 FBW control system because it has supplied both hardware and software to Parker for the main flight control computers (FCC) from the onset of the program. The FCCs are the top-level digital brains of the FBW system that tell the REUs how to command the control surfaces. Embraer officials said that, in contrast to Parker, BAE Systems' FCC hardware and software development was “flawless” throughout the program.

“It's behind us now, thank goodness. We're moving on. All the tough questions are going to come [out]. How did we get here? What did we learn? And all of that stuff will be handled by Parker. I guess they're the people who have learned the most from this,” says Ernest Edwards, president of Embraer Executive Jets. So, how did Embraer get the FBW development program back on track?

“In a nutshell,” says Edwards, “it took a lot of hard work and dedication by all the teams involved. Once we identified the delay, it was a case of getting all the parties around the table and saying 'OK. Let's get involved and find out what we need to do to minimize this delay . . .' It was more a team effort than any individual party. It wasn't so much of the problem being a problem, the problem was the delay and how do we recover.”

Edwards' “team effort” reference soft sells the role played by Embraer's and BAE Systems' engineers in rectifying the FBW software problems. Without their involvement at the “25th hour,” the aircraft still might be a hangar queen.

“What's past is done and we have a great airplane,” Edwards concludes.

Getting Development Back on Track

Now the onus is on Embraer in Brazil to forge ahead in the next several months with a 2,000-hr. flight test campaign that's required for earning type certification by the end of 2013 or beginning of 2014.

Learning from the Phenom 100/300 development program, Embraer built a complete Legacy 450/500 engineering office at its Gavião Peixoto flight test facility that will accommodate 200 engineers from Embraer and its program partners who will work side by side with test pilots during the flight test campaign to expedite development work. The team will include systems, powerplant, avionics, interior and manufacturing engineers, plus supply chain specialists.

“Everything will be there. I think this is a very good approach. So, the engineers will be very close to the flight test campaign, very close,” says Marco Tulio Pelligrini, Embraer Executive Jets COO.

Two prototype and two fully production conforming aircraft will be used for the flight test campaign. The first two aircraft will be fitted with full flight test instrumentation and used primarily for envelope expansion and performance evaluation. The second prototype is slated to fly “as soon as it can” after the first prototype takes flight, perhaps “a matter of weeks,” says Ricardo Maltez, Legacy 450/500 program manager.

The third aircraft, fitted with all production systems including the interior, is slated to fly by year-end. It has been used for high-intensity radiated fields (HIRF) and lightning tests. The fourth aircraft — “the actual finished article,” says Edwards — will undergo hundreds of hours of function and reliability proving, including multiple takeoffs and landings, to assure a smooth entry into service in 2014. Edwards said the goal is to wrap up all the lessons learned from the first three flight test aircraft into the fourth, so that engineers can wring out as many problems before production aircraft are delivered to customers. The fourth aircraft is slated to start flying in the second half of 2103.

“We learned a lot from the Phenom, the first airplane we designed for the market. Maturity plays a very important role in the game, so we learned from the entry into service of the Phenoms. We had some 'spots' as you know,” says Tulio Pelligrini.

“[For the Legacy 450/500,] we created a dedicated team, a broader team with our suppliers. And we've run lots and lots of tests, much earlier than we did with the Phenom 100,” he continued. “We did HALT [highly accelerated life testing] to monitor the quality and the assurance of the components. In terms of the interior, we built an actual interior and installed it in a real fuselage and then 'flew' it. We took maybe 300 or 400 people to Brazil, including salespeople and customers, and we spent hours aboard the mock-up. They had lunch there, they had dinner there, people slept on the airplane. We even used the lavs. So, we've had the chance to learn before we start delivering airplanes to customers.”

“We don't see any major challenge. It's just getting it done. We've certified fly-by-wire airplanes before and it is a big step forward, but we are very comfortable with the control laws,” adds Maltez.

“One of the key aspects is maturity,” Maltez continued, “something we're taking very seriously, both on product support and the factory itself. As a real example, we just finalized our lightning and HIRF ground tests. We'll have one and a half to two years before entry into service to correct what we find. Typically, in the past, we would do those tests later on in the flight test program. So, this is maturity. We're catching those [problems] right now.”

Embraer took full advantage of the lull time in 2011 and 2012 to work on other parts of the aircraft, as well. “Iron bird” avionics, systems and interior mock-ups have been used to mature components in preparation for entry into service.

“While we waited for first flight, we haven't been idle at all,” Edwards comments. “The fourth airplane will gain maturity on the interior and all the systems even while the certification process is going on. So, the aircraft will be ready for entry into service on Day One, rather than entering into service and then maturing.”

Weight control will be critical to attaining Embraer's performance goals for the airplane, including the Legacy 500's ability to fly four passengers 3,000 nm at Mach 0.80 and landing with 200-nm NBAA IFR reserves. Such range makes possible flying nonstop from New York to London; Los Angeles to Kahului, Hawaii; Toluca, Mexico, to Gander; and Paris to Abu Dhabi.

It also will be able to fly eight passengers more than 2,800 nm and land with the same reserves, so it will be able to fly a 1,600-lb. payload from Los Angeles to New York, Delhi to Beijing, or Kuala Lumpur to Tokyo. Range with the maximum payload of 2,800 lb. will be more than 2,500 nm. Up to 11 passengers and one flight attendant can be seated in the cabin, so payload capacity shouldn't be an issue.

Embraer also predicts the airplane will have a 4,600-ft. TOFL and a 2,400-ft. landing distance assuming sea level ISA conditions. It will be able to climb to an initial cruise altitude of 43,000 ft. in 22 min. Maximum cruise altitude will be 45,000 ft. while the aircraft maintains a 6,000-ft. cabin altitude.

“So far, wind tunnel tests tell us we are doing just fine,” says Edwards.

But meeting weight targets is key to attaining such performance goals. While Embraer declines to discuss target weights for the aircraft, Maltez is confident about weight control. “Weight is always an issue in every development [program]. I don't know any [program] where we didn't find challenges. But we are very, very close to our targets, in the range of 1%.”

Keeping the interior completion weight under control is just as important. Austrian firms Fischer Advanced Composite Components and List Group are supplying the interior and Maltez says that “weight is not an issue.”

Performance, weight and high reliability are utmost goals. “This program needs to be right out of the box,” says Edwards.

Raising the Technology Bar

Embraer will face fierce competition in the super-midsize class from Bombardier and Gulfstream when the Legacy 500 enters service in early 2014. But the Brazilians are betting that their newcomer will offer higher levels of technology that will help win them market share.

The Legacy 500, which will be followed in one year by the shorter, 2,300-nm-range Legacy 450, will be the first business aircraft in this class to have three-axis FBW flight controls for elevators, rudder, ailerons and multifunction spoilers. The next least-expensive business jet with three-axis digital flight controls is the $52 million Dassault Falcon 7X. Embraer and Dassault both fit their FBW cockpits with sidestick controllers to increase legroom for the flight crew and provide an uninterrupted view of the instrument panel.

The flight control system will afford full envelope protection, including over speed/Mach, overstress and excessive angle of attack (AOA) limiters. The AOA protection system eliminates the need for a stall warning stick shaker and stick pusher, similar to the system installed in Embraer's E-Jets. The AOA limiter should allow a razor-thin margin to Cl max, thereby resulting in lower V speeds and shorter runway requirements than would be possible if these speeds were referenced to a conventional stall shaker or pusher.

The FBW system also includes a beta, or sideslip, limiter to prevent over-stress of the vertical stabilizer. In case of engine failure, the system also provides pilots with a target sideslip indicator on the primary flight displays (PFD) to help them extract maximum engine-out climb performance in proportion to asymmetric thrust.

Similar to the E-Jets, the FBW system of the Legacy 450/500 has soft limits for pitch and roll that return the aircraft to +30/-15 deg. pitch and +/-33 deg. of bank if the sidestick is released. However, there are no hard limits to pitch and roll if a pilot keeps pressure on the sidestick and stays within the minimum AOA and top speed limits. But the maximum available 30-deg.-per-second roll rate virtually eliminates the temptation.

FBW also offers a smoother ride for passengers because the flight control computers correct aircraft attitude for minor bumps much faster and more precisely than humans can react. The system also reduces pilot workload because the crew only has to make changes to the flight path. Let go of the sidestick and the aircraft will maintain the flight path within flight envelope limits.

FBW also potentially reduces aircraft empty weight because the airframe doesn't have to be overbuilt to provide margins for ham-fisted pilots. In addition, FBW has a stability augmentation function that allows the weight and balance envelope to be expanded so the aircraft can be safely flown with a more aft c.g. This results in reduced trim drag, thereby improving fuel efficiency and range performance.

Four solid-state Goodrich SmartProbe air data/AOA sensors eliminate pitot and static plumbing along with a moving AOA vane. SmartProbes should slash the cost of pitot/static/AOA system maintenance by a factor of seven.

Rockwell Collins is supplying its Pro Line Fusion equipment for the Legacy 450/500, one of the latest avionics designs. The two Embraers feature four 15-in. landscape configuration flat-panel displays with standard synthetic vision, dual FMS and electronic charts. The base package also includes a hybrid TCAS/Mode S traffic surveillance system, Class A TAWS, solid-state weather radar with Doppler turbulence detection and dual comm/nav/surveillance radios.

Most optional equipment will be certified after the aircraft enters service. Options include HUD and EVS, VNAV, auto-throttles, WAAS LPV, RNP 0.3 and dual IFIS file servers for paperless chart operations, plus required time of arrival, 4-D nav and takeoff and landing distance computer for the FMS. Rockwell Collins MultiScan weather radar, ADS-B OUT, predictive wind-shear and XM satellite radio or XM data link weather also will be offered at extra cost, along with Link 2000+ CPDLC for Europe, single or dual HF transceivers and VHF data link for ACARS.

Other standard equipment includes a brake-by-wire system with EICAS temperature monitoring and an optional three-level auto-braking feature. Low weight, long-life NuCarb heat packs should reduce the cost per landing.

Passenger Environment

Since the Legacy 500's maximum cabin altitude is 6,000 ft. at FL 450, passengers will experience less high-altitude fatigue on missions as long as 6-7 hr. Embraer also is focusing on minimizing cabin sound levels, also helping passengers to arrive more rested.

Honeywell will provide its Ovation Select cabin management system that incorporates an Ethernet architecture and features 1080p HD video, surround sound, multiple media inputs and Wi-Fi. Gogo Biz, Iridium and Inmarsat satcom connectivity solutions will be available.

What's missing? Honeywell has yet to embrace the Apple revolution in cabin management and AV entertainment systems. Company officials say they're looking into Apple device compatibility, but for now Rockwell Collins is stealing the show with its Airshow app for iPads and iTunes/Apple TV audiovisual on-demand (AVOD) system that's becoming available for its Venue CMS/AV systems.

Embraer is positioning the Legacy 500 in the narrow niche between the longer-range midsize class and the super-midsize class. As such, the aircraft has a slightly smaller cabin cross-section and shorter cabin length than its two main super-midsize competitors, the Bombardier Challenger 300 and Gulfstream G280. Overall cabin volume is 820 cu. ft. compared with 860 cu. ft. for the Challenger 300 and 935 cu. ft. for the G280. But it also has 30-75 min. less endurance compared respectively to those competitors, so cabin size is well matched to range performance.

Compared to midsize competitors in the 3,000-nm range class, such as the new Cessna Citation Sovereign and Gulfstream G150, the Legacy 500's cabin is wider, taller and longer, plus it has a flat floor. Cabin volume also is one-third to three-quarters bigger.

The standard interior features a forward galley with sink, fore and aft four-seat club sections, and a full-width aft lav with hot and cold running water, vanity sink and vacuum toilet, a feature it shares only with the G280. Each pair of facing chairs converts into a virtually flat berth. The aircraft offers the largest cabin windows in this class and each transparency is positioned next to a seat for the best view.

The right-side forward galley has a standard sink with a 4-gal. fresh water tank and hot and cold running water. The standard configuration has an ice drawer and multiple storage compartments.

Embraer has a long list of cabin options. Optional cabin configurations offer a forward flight attendant's seat, left and/or right aft three-place divans and a belted potty seat. Galley options include AC power outlets for appliances, video monitor and dinnerware storage. Adjustable lumbar support, heating and massage functions are available for individual passenger chairs.

Carry-on luggage and bulk baggage capacity long have been design priorities for Embraer Executive Jets. The Legacy 500 has a heated and pressurized 40-cu.-ft. luggage compartment just aft of the lavatory and a 110-cu.-ft. unpressurized external aft baggage compartment.

Tough New Brazilian Competitors in 2014 and 2015

After a one-year hiatus caused by the Legacy 450/500's FBW development problems, once again people in Montreal, Savannah and Wichita are paying close attention to the Brazilian jet maker's blend of cabin size, range and technology, plus price.

Currently priced at just under $20 million, the Legacy 500 will be highly competitive with both longer-range midsize and shorter-range super-midsize aircraft, including the all-composite $19 million Bombardier Learjet 85. The Canadians also are mulling over an improved version of the Challenger 300 with more range and tanks-full payload in an effort to move the aircraft away from the Legacy 500 and closer to the Gulfstream G280.

Cessna officials still wince at the one-two punch of the Phenom 100 and 300 that knocked down Citation CJ1+ and CJ4 sales. So, the Wichitans are wary about the arrival of the Legacy 500. Doubtlessly, the threat influenced the firm's decision to upgrade a second-generation Citation Sovereign that will carry more tanks-full payload, cruise 150 nm farther and offer considerably more advanced avionics. It's due to enter service in 2013 as a preemptive move against the Brazilians.

Gulfstream, too, is monitoring the progress of the Legacy 500 because of its potential impact on G150 sales. While Embraer's new super-midsize is $4 million more expensive than Gulfstream's smallest production business aircraft, the two aircraft have similar range. However, the Legacy 500's 75% advantage in cabin size and FBW flight control technology could tempt buyers and potentially syphon off future G150 orders.

Then, in 2015, the Legacy 450 arrives. It has the same cross section as the Legacy 500 and all the same technology features, but it has a shorter fuselage and carries less fuel. It's aggressively priced at about $16 million to compete head-on with mainstream midsize business aircraft.

In short, 2014 and 2015 promise to be milestone years in the history of business aviation. If Embraer earns as much market share with its new midsize Legacy 450 and super-midsize Legacy 500 jets as it did with its Phenom 100 and 300 lights, plus Legacy 600/650 regional jetliner derivatives, some well-established business jet manufacturers could take a bruising. BCA