Story ID: 040Legacy450AINNov15EBAYNM
Legacy 450 Flies Fine Steep Approach
By: Matt Thurber
Caption: Testing of the steep approach mode for the Legacy 450 and 500 is done and Embraer expects certification next month.
Word Count: 1169
Embraer expects to receive steep approach approval for the Legacy 450 “midlight” and 500 midsize jets next month, and AIN flew the 450 in Brazil on September 11 to try the new capability.

The Legacy 450 and 500 share so much commonality in systems, avionics, fly-by-wire flight controls, handling and pilot techniques that the FAA has issued a “AAA” common type rating, which means no differences training is required. Having flown both airplanes–the Legacy 500 twice and the 450 once–I can confirm that the feel and handling are exactly the same.

The major physical difference between the two airplanes is the fuselage, which is unique to the 450 and not just a 500 fuselage with segments removed. This was necessary so that the 450’s windows would be positioned properly for passengers’ seat locations. The other difference, of course, is performance. The 450’s range is less than the 500’s–2,575 versus 3,125 nm–but otherwise the airplanes are similar, with small differences in takeoff and landing distance, although the 450’s full-fuel payload is 27 pounds greater. Both share the same Rockwell Collins Pro Line Fusion flight deck and Honeywell HTF7500E engines, but thrust on the 450 is 6,540 pounds per side while the 500’s engines each deliver 7,036 pounds.
 Comfortable Cockpit
The cockpit of the Legacy 450 felt instantly comfortable. It is so well laid out and systems and controls so logically placed that I don’t think it will take pilots long to learn to fly the new Legacys. The fly-by-wire flight controls are operated by a sidestick for each pilot, functioning individually; the rudder pedals are mechanically connected between the pilot and copilot side. Elimination of the bulky yoke is a big benefit of fly-by-wire, and the Legacy 450/500 cockpit takes full advantage of all the extra space. There is even a slide-out work table for each pilot.

I flew left seat alongside chief test pilot Eduardo Camelier for the flight from São José dos Campos Airport, where Embraer’s headquarters is located and the new Legacys are assembled. (Legacy 450/500 assembly at Embraer’s facility in Melbourne, Fla. will begin in the middle of next year.) Our takeoff weight, with two pilots and three Embraer personnel, was nearly 29,500 pounds, well below the 35,274-pound mtow. We carried 5,660 pounds of fuel, about half of the 10,851-pound maximum fuel load.

For this flight, we decided not to climb directly to the 450’s initial cruise altitude of FL430 (maximum is FL450), but stopped at FL300 so we could spend more time flying maneuvers and the steep approach. As I did with Camelier during my first Legacy 500 flight, we pushed the 450’s fly-by-wire flight controls to the limits of the flight protection envelope. In the high-speed regime, we left the autothrottles at a high power setting, pushed the nose down and let the airspeed build to the Mach 0.83 Mmo redline, at which point the fly-by-wire automatically pulled the nose up to keep the speed within limits.

After descending to 15,000 feet we explored the other end of the envelope, decelerating with full flaps and landing gear down to the minimum possible flying speed at 1.04 Vso. I had experienced this in the 500, and it was once more amazing to be flying a 30,000-pound business jet at 87 kias and retaining full control. While in this configuration, I held the stick fully aft and moved it from side to side and watched as the flight control system automatically maintained the 1.04 Vso margin; in the bank the airspeed climbed slightly to about 94 kias to maintain the margin over stall speed, then it dropped below 90 kias as the wings leveled.
 Flying the Steep Approach
To prepare for the real thing, we first flew in the steep approach configuration while still in the mid-teen altitudes, using a 5.5-degree glideslope. This angle is adjustable, and we moved it down to 7.5 degrees to see what the view outside the windshield looked like. The 7.5-degree angle is a required certification test. The steep approach mode is activated by a button: on this 450 it was on the aft center console but will be moved to the copilot’s right ledge area for the certified steep approach configuration.

In steep approach mode, the flaps must be fully extended. After the pilot pushes the button, a white CAS messages illuminates, showing that the mode is armed. The system remains in the armed mode until selection of full flaps and gear down, at which point it engages and the CAS message turns green. The mode turns off automatically in certain conditions, including flaps not full, aircraft on ground, takeoff/go-around, angle-of-attack near stall or flap extend speed exceeded.

Rather than selecting just open or closed, the fly-by-wire system modulates the wing spoilers throughout their extension range to maintain the selected glideslope. When Camelier changed the glideslope to 7.5 degrees and I pitched the nose down, the spoilers opened further to maintain the descent angle without increasing airspeed, and we could see the actual amount of spoiler deployment on the flight control synoptic on the cockpit displays. According to Camelier, “When going to a pitch angle greater than 6.5 degrees, the system changes the sidestick-versus-spoiler deflection curve.”

I then flew some maneuvers trying out the 450’s direct mode, which shuts off envelope protection and makes the flight controls act like those in a normal airplane. In direct mode I flew an approach to stall and recovered, and the 450, like the 500, handles this without any wing drop. In direct mode I had to use the elevator trim switch because this mode deactivates automatic adjustment.

We switched back to the fly-by-wire normal mode and flew two touch-and-goes at São José dos Campos before setting up for the steep approach. I set the autobrake control to medium, which would help us get stopped if we used more runway after the steep approach. Camelier assured me that a normal touchdown is possible after the steep approach, and this turned out to be the case. I set up the 450 at about 1,500 feet agl closer to the runway this time, and Camelier switched on the steep approach mode. The autothrottles and spoilers helped manage the descent, and I used the fly-by-wire’s TCS trim button on the stick, which works in landing configuration, to set the airspeed right at Vref. Staying on the 5.5-degree glidepath was just a matter of a few tiny moves of the stick, but the fly-by-wire system maintains the selected flight path, so a lot of stick movement is unnecessary.

I was getting better at avoiding too much flare before the touchdown in the Legacys, and as we passed through 50 feet the autothottles retarded, I pulled the nose gently to the horizon and the Legacy 450 touched down on the mains. The automation then lowered the nose and applied the brakes to slow us down with plenty of runway remaining.

Embraer expects to receive steep approach certification for both the Legacy 450 and 500 in the middle of next month.