MIKE GERZANICS / SAN JOSE DOS CAMPOS
Embraer's first move into the business jet market is aimed at the super mid-size sector. Drawing on its regional jet expertise, it has come up with a strong competitor
Spurred on by its success withtheERJ-135/140/145 series of regional jets, Embraer has made its first foray into the business-jet market. Based on the 37-seatERJ-135, the Legacy is aimed at the increasingly popular super mid-size business jet sector. Initial results have been encouraging: the Brazilian manufacturer has booked 73 firm orders and 92 options for the Legacy, split almost equally between the two models available - Shuttle and Executive.
The Shuttle variant is almost identical to the ERJ-135. Optimised for corporate shuttle operations, the aircraft offers cabin layouts seating 16 at a generous pitch of 43in (1.1m), and up to 37 at an airline-like pitch of 31in. With 5,135kg (11,310lb) of fuel, a Shuttle seating 18 passengers has a range of 3,245km (1,750nm). The cockpit of the Shuttle is identical to that of the Executive, but with a lower level of standard avionics. Priced at $17.1 million, the Shuttle is slightly more expensive than an ERJ-135 and gives corporations the ability to move groups of employees between distant sites at reasonable cost.
The Executive model is markedly different in several aspects as it is optimised for the classic business-jet role. Fuel capacity is increased to 8,242kg, through the addition of underbelly fuel tanks located forward of the wing and smaller aft fuselage tanks. Wing area is increased and drag reduced with the addition of 1.34m (4.4ft) high winglets. These two changes give the Executive transcontinental legs, with a range of 5,745km when carrying 10 passengers. Cabin size remains unchanged from the Shuttle, but the level of interior appointment is higher. Several interior configurations are available providing seating for 11 to 16 passengers.
A major factor in the early success of the Legacy has been its large cabin. At $20.4 million, the Executive offers an interior nearly as big as that of a large-cabin Gulfstream G400 for the price of a mid-size Gulfstream G200. At 12.94m long, providing 39.9m3 (1,406ft3) volume, the Legacy is divided into three seating areas, the aftmost featuring a pullout bed. Further aft, but still forward of the engines, is a lavatory, a door in its aft wall providing in-flight access to the pressurised baggage compartment. This offers 6.79m3 of space for up to 454kg of baggage, outclassing the competition.
The ERJ-135/145 was developed for high-frequency regional airline operations, with utilisation rates of 2,500-3,000h a year. Typically, business jets are operated for 500h a year, a much less demanding pace. Operators will benefit directly from the robust airliner design, and the operational experience accumulated by the large airline fleet. Solutions to problems uncovered in airline operations can be applied to the Legacy long before the problem surfaces in the business jet fleet. Embraer's Total Legacy Care and engine supplier Rolls-Royce's Corporate Care programmes offer operators the option of fixed hourly maintenance costs.
Flight International was given the opportunity to see if the Legacy pilot is equally well cared for. The aircraft evaluated at Embraer's San Jose dos Campos facility, near Sao Paulo, Brazil, was an Executive model with optional, uprated R-R AE3007-A1E engines.
Extra thrust
Producing 7,955lb thrust (35.4kN) each, these engines have been specified by most Executive buyers in lieu of the standard 7,430lb-thrust AE3007-A1P.
Senior flight test manager Capt Sergio Costa pointed out some of the Executive's features during the preflight inspection. A large forward-fuselage fairing provides room for two underbelly fuel tanks without impinging on cabin space. The supercritical-section wing is swept 22.7°, and has a fixed leading edge. Four vortex generators on the lower surface protrude forward of the leading edge. Located ahead of the ailerons, they enhance roll control at high angles of attack (AoA), with the additional benefit of increasing lift by acting as virtual slats.
The blended winglets reduce cruise drag by up to 3.5% at some conditions, but they also degraded the baseline Legacy's directional stability. Two ventral strakes were added to the aft fuselage to regain the desired stability margins for the Executive model.
Access to the cabin is via a hydraulically operated cabin door with integral steps. Stored hydraulic pressure alone is sufficient for four door cycles. The spacious cockpit has room to store a flight bag outboard of the seat. Manual fore/aft adjustments as well as electrical up/down movement allowed me to settle comfortably into the seat. Field of view out of the four windows was good, the outboard quarter of the wing being visible.
Comparable in size to the Bombardier Challenger's cockpit, I found the Legacy's flightdeck more open and airy, while providing a higher seating position. System controls on the overhead panel use both rotary and lighted pushbutton switches. A dark-cockpit design philosophy was used: when systems function normally there are no lights on the panel.
The Honeywell Primus 1000 integrated avionics, which include five 200x175mm (8x7in) colour CRTs, give each pilot a primary flight display (PFD) and a multifunction display (MFD), as well as a central engine indicating and crew alerting system (EICAS) display. Panel clutter is further reduced by the use of dual radio management units and a liquid-crystal integrated standby instrument.
Two control display units on the centre pedestal are used to manage the dual flight management systems (FMSs). Two inertial reference systems (IRSs) are installed, as well as dual GPSs. After initial power-up IRS alignment took only 5.5min.
The auxiliary power unit start, in preparation for engine start, was monitored on the EICAS. Peak exhaust gas temperature of 465°C (870°F) was well below the maximum of 884°C. After checking both throttles were in IDLE, the right engine was started by rotating its selector to START. At 31% N2 the full-authority digital engine control (FADEC) opened the fuel valve and light off was immediate. Peak inter-turbine temperature (ITT) was 500°C and idle RPM of 26% N1 was reached in 35s. Left engine start was similar, with ITT peaking well below the 800°C limit.
After start the only unusual step was to select the other FADEC for each engine on the overhead panel. This checked the operation of both the engines' identical controllers.
Take-off speeds and engine thrust settings were entered before taxi. Bumping the throttles up slightly started the aircraft rolling, with idle power giving a reasonable taxi speed. Hydraulically actuated nosewheel steering, controlled by a small tiller on the left side console and by the rudder pedals, allowed easy tracking of the taxiway centreline. When used together, tiller and pedals gave a tight turn radius: a 360° turn required less than 19m lateral offset.
Flaps were set to 9° for take-off, and a control sweep performed before lining up on the runway. Once cleared I advanced the throttles to the THRUST SET position, just short of the firewall. In this position, take-off, maximum continuous, climb and cruise thrust settings can be selected using pushbuttons aft of the throttles. Three levels of take-off thrust are available: 90%, 100% and 107% of nominal maximum. For our take-off the 90% level was selected.
Yoke forces
After brake release the 19,782kg aircraft (empty weight including crew was 13,591kg) accelerated down the runway. At 124kt indicated airspeed Costa called "rotate". I found the yoke forces required to achieve the desired 14° lift-off attitude somewhat excessive. On the calm, 26°C day the Legacy lifted off the runway 30s and 1,200m after brake release. Gear and flap retraction caused little change in yoke forces as we accelerated to the initial climb speed of 240kt.
I followed the FMS's pitch guidance for the climb to the aircraft's ceiling of 39,000ft (12,000m). At 3,000ft above mean sea level (1,000ft above ground level) climb power was selected with the thrust pushbutton. The FADEC now acted as an autothrottle, keeping N1 at its optimum level throughout the climb. Passing 10,000ft the flight director commanded a slow acceleration, reaching 290kt at 12,000ft; 290kt was held until Mach 0.65 was reached after passing FL216. The autopilot was engaged, and smoothly tracked both pitch and roll commands throughout the remainder of the climb. The climb from 5,000ft to 39,000ft, including a number of ATC-directed 90° turns, took 25min and burned 656kg of fuel.
Once level at 39,000ft, Costa selected the cruise thrust level and recommended I let the aircraft accelerate. The Legacy has a maximum operating Mach number (MMO) of 0.80, about 10% lower than its Falcon and Gulfstream rivals, which I had feared would translate into a slow cruise speed. In less than 5min the aircraft reached M0.795/246kt, where I pulled the throttles back out of the THRUST SET position to stay below redline. Total fuel flow was 0.280kg/s (0.625lb/s) as the 18,670kg aircraft held 457kt true airspeed.
After disengaging the autopilot, I found the aircraft easy to hand fly, even at the upper righthand corner of its flight envelope. A series of sharp inputs in each of the three control axes showed the Legacy to be stable. My fears had been unfounded - the Legacy cruised quite smoothly just below its MMO.
I next did a series of steeply banked turns. Passing 55° of bank an aural "bank angle" caution was annunciated. I continued pulling until I felt mild airframe buffet at 65° of bank and slightly more than 2g. Buffet investigation complete, I slowed the aircraft to M0.75, where total fuel flow was 0.270kg/s at 430kt. I next slowed the Legacy to M0.707, the long-range cruise speed, where total fuel flow was 0.225kg/s at 405kt.
Costa took control of the aircraft and accelerated to M0.79 as I left the flightdeck to sample the cabin environment. At 39,000ft, the automatic pressurisation system maintains a comfortable cabin altitude of 8,000ft. Deck angle was less than 2° nose up, making walking through the cabin easy. The ambient noise level was fairly low, the loudest area being by the forward entry door. Quietest was the third seating area, where the sofa/pullout bed was located.
Capt Marcelo Romanelli, acting as a safety observer, installed the noise curtain over the main door, which markedly quietened the cabin. My survey of the cabin complete, I returned to the cockpit for a descent to 18,000ft. I pushed the power to the THRUST SET position, selected cruise, and nosed the aircraft over.
As airspeed increased past MMO into the red "overspeed indication" bar, the flight director commanded a climb to reduce airspeed. I engaged the autopilot, which followed the flight director's guidance and raised the nose to slow the aircraft below MMO. I then retarded the throttles to idle and descended to 18,000ft in preparation for slow speed manoeuvring.
The first stall was in a clean configuration. I slowed the 18,170kg aircraft at 1kt/s. When the aircraft was within 10° of stall AoA, a pitch limit indicator appeared on the attitude director indicator. The stick shaker triggered at 126kt indicated airspeed, and the pitch limit indicator turned amber. Ignoring the shaker I continued to hold aft yoke pressure. The wings remained level and nose steady on heading as the aircraft slowed further. There was no classic pitch break and little airframe buffet as the pitch limit indicator turned red and the stick pusher fired at 119kt. Releasing backpressure and advancing the throttles recovered the aircraft to normal flight.
Stall tests
The gear was lowered and flaps set to 9° for a take-off configuration stall. At 114kt the stick shaker activated, followed by the stick pusher firing at 109kt. Holding the red "stk pusher" disconnect button on the yoke allowed me to slow the aircraft to 104kt. Even at this low speed, the wings remained level and heading steady. Recovery to normal flight was accomplished by lowering the nose. The pitch limit indicator gave a real-time display of what attitude could be held to recover rapidly to level flight without encountering a secondary stall.
A landing configuration stall, gear down and flaps 45°, and recovery was similarly uneventful, with shaker activating at 105kt and pusher firing at 100kt.
Rather than returning directly to San Jose dos Campos, Costa suggested we do an approach and landing at Embraer's new flight test facility at Gaviao Peixoto. Located in a rural citrus-growing area 300km northwest of San Jose dos Campos, it has a 3,050m-long runway with a 1,525m-long overrun, as well as ample space for hangers to support both flight test and future production.
Rate of descent at idle power and 280kt was 3,000ft/min. Deploying the speedbrakes increased the rate of descent to 4,900ft/min, and caused no pitch force changes as the pitch trim system automatically compensated with more nose up trim.
After slowing to 230kt and retracting the speedbrakes I turned the yaw damper off. A sharp rudder input excited a dutch roll. The resulting motion, controls free, exhibited lots of roll, and showed little tendency to damp out. Co-ordinated use of the rudder arrested the motion. After another sharp rudder input I turned the yaw damper back on. It quickly stopped the unwanted motions. While required for autopilot operations, the yaw damper is not required for dispatch - nor was it missed during our hand-flown high-speed cruise operations at 39,000ft, when it was turned off.
Several miles from Gaviao Peixoto, Costa pulled the right throttle to idle to simulate an engine failure. On final approach the gear was lowered and flaps set to 22°. As I stabilised the aircraft at 135kt for final approach the rudder was extremely effective, with less than an eighth of available rudder trim required to maintain co-ordinated flight.
Engine power response on the left engine was good, allowing me to closely maintain speed during the approach. Good control harmony and near-centreline mounting of the engines made flying the approach quite easy. On touchdown I retarded the left throttle to idle, causing two speedbrake panels on each wing to deploy automatically as ground spoilers.
Uneventful shutdown
Moderate application of toe brakes and reverse thrust on both engines quickly slowed the aircraft to taxi speed by the mid-field turnoff point. Shutdown and post flight procedures were uneventful. During the 2h 6min first leg of the evaluation flight we had burned 2,109kg of fuel.
After a short tour of Embraer's new facility it was time to return to San Jose dos Campos. For the second take-off, the 90% thrust level was again selected. Decision speed (V1) and rotation speed were both 116kt. Take-off safety speed (V2) was 125kt. Lined up on the runway for take-off, I held the toe brakes and put the throttles to the THRUST SET position.
After the engines stabilised, a green automatic take-off thrust compensation system (ATTCS) advisory message was displayed on the EICAS. To improve climb performance in the event of an engine failure, ATTCS increases thrust in the operating engine by 10%. Accelerating through 116kt Costa called "rotate". As the main gear lifted off the runway he pulled the left throttle to IDLE, simulating an engine failure. About two-thirds of the available rudder travel was required to keep the nose tracking straight on runway heading.
I climbed the aircraft at V2 and retracted the gear. Checking the EICAS display confirmed thrust on the "good" engine had been increased to 100% by the ATTCS. Just 80% of rudder trim was needed to zero out forces during the climb. Satisfied with the Legacy's response to an engine failure shortly after lift off, we used both engines to climb to 25,000ft for the return to San Jose dos Campos.
Once level at 25,000ft, I let the speed increase to 315kt, just below the Vmo of 320kt. The 16,950kg aircraft was travelling at 466kt true airspeed and had a total fuel flow of 1,583kg/h. During the engine-out manoeuvring a slight fuel imbalance had developed. Crossfeed procedures were remarkably simple. Moving a single rotary switch on the overhead panel to the LOW fuel system position opened a crossfeed valve and turned off the appropriate boost pumps in the proper sequence. While manually configuring a fuel system to crossfeed is not difficult, all too frequently the wrong boost pumps are turned off or positive fuel pressure not maintained to an operating engine.
Final descent for the ILS approach to runway 15 was accomplished with the gear and speedbrakes extended, as ATC had kept us at too high an altitude to use a more economical idle-power clean descent. Level at the glideslope intercept altitude I armed the flight director's approach mode. Once captured, the flight director's commands were easily followed and allowed me to track both the localiser and glidepath accurately.
Flaps were set to 45° for the approach, giving a target speed of 126kt for the 16,625kg aircraft. At 200ft radar altitude "Minimums" was announced, and I continued visually. The Legacy's trailing-link main landing gear made for a smooth touchdown. After flying the nosewheel on to the runway, Costa set the flaps to 9° for the touch-and-go manoeuvre. At 126kt he called rotate. The gear was retracted and flaps left at 9° for the climb to downwind. During the visual circuit I found pitch and roll control forces to be well harmonised, but somewhat heavy.
The full-stop landing was on centreline within the first 500m of the runway. Thrust reversers and toe brakes brought the Legacy to a halt after a ground run of 1,300m. Slowing through 21kt groundspeed caused the speedbrakes to stow automatically for taxi back to the ramp. As was the case at Gaviao Peixoto, shutdown and post-flight procedures were easily accomplished.
Impressive package
Overall, I was quite impressed by the total package offered by the Executive version of Embraer's Legacy. Its cabin is one of the biggest available in a business jet at any price. Its moderate acquisition cost and high level of standard equipment make the aircraft even better value. Operating costs should be easy to predict and control given the large number of ERJ-135/145 aircraft in airline service.
The Legacy's range is on par with similarly priced super mid-size business jets, such as the Cessna Citation X, Bombardier Challenger 300 and Dassault Falcon 50 or 2000, yet it offers a larger cabin. Only when judged against more expensive large-cabin business jets such as the Challenger 604 and Gulfstream G400 does the Legacy's 5,745km range suffer by comparison. The aircraft's ability to cruise comfortably at speeds approaching M0.8 shows that its cabin comfort does not come at the expense of speed.
An outstanding performer in many categories, a buyer need not be blinded by passion to purchase a Legacy Executive. The numbers speak for themselves.
Source: Flight International
