Bombardier is giving its super mid-size competitors run for their money with the Challenger 300, which offers good value and spacious cabin with low operating costs
When formally launched at the Paris air show in 1999, Bombardier's new super mid-size business jet was named the Continental, to emphasise its US transcontinental design mission. Later the aircraft was rebranded the Challenger 300 to associate it more closely in customers' minds with the company's Challenger 604, the value-for-money leader among large business jets.
In fact, the Challenger 300 is designed to bridge the gap between Bombardier's Learjet and Challenger lines, and is intended to combine the traditional strengths of the two families: speed and style with size and reliability. And while the name may have changed since the programme's inception, one thing has remained constant: Bombardier's drive to develop an aircraft that delivers more than the competition for less money.
The Challenger 300 is an all-new aircraft and, after an aggressive four-year certification programme, received Transport Canada type approval on 31 May 2003, followed on 4 June by US FAR 25 certification and on 31 July by European JAR 25 approval. On the eve of the aircraft's January entry into service with Bombardier's Flexjet fractional-ownership subsidiary, Flight International was invited to fly the Challenger 300 at Bombardier's Wichita, Kansas flight test facility.
The design's Challenger lineage is readily apparent in its four cockpit windows. While arranged like those of the original Challenger 600, their taper evokes a more Learjet-like appearance. From some angles the fuselage looks as large as that of the Challenger 604, but its cross-section is more ovoid than circular. The flat-floored cabin offers the same 1.85m (6ft) of headroom as the 604, and, while not as wide at 2.19m, is only slightly narrower than that of the large-cabin Gulfstream 400.
Cabin layout
The cabin is 7.22m long, including an aft lavatory. Typical seating is for eight passengers in a double-club arrangement. An optional side-facing divan is certified to 16g, allowing its use for take-off and landing and increasing seating to nine. The interior is integrated by DeCrane, which uses a fit jig to ensure precise alignment of components at the Tucson completion centre. Eventually both production and completion will move from Wichita and Tucson to Bombardier's Montreal Dorval plant.
Bombardier pilots Ed Grabman and David Ryan accompanied me on the pre-flight walk-around inspection. The most prominent feature of the aircraft is its large wing, which has a relatively simple planform and structure for ease of manufacture. The highly polished fixed leading-edge droops slightly on the outboard half. The notch where the droop starts and three small vortilons outboard of it are instrumental in preventing spanwise flow along the 27%-swept supercritical wing without resorting to fences.
At 48.5m2 (520ft2), the Challenger 300's wing is the smallest in the super mid-size class, but only by a narrow margin. The aircraft's closest competitor, Raytheon's still-to be-certificated Hawker Horizon, has a 49.3m2 wing with higher sweep and no winglets. Bombardier says the Challenger 300's slender 1.15m-high winglets reduce lift-induced drag by around 17% in the cruise.
Power is provided by two Honeywell AS907 turbofans, recently redesignated HTF7000s, each flat-rated at 6,830lb thrust (30.4kN) to ISA +15°C (59°F). Pre-flight inspection was easily performed from ground level. Engine oil level is checked with switches behind an access panel just forward of the right wing leading edge. Fuel quantity and distribution can also be checked at the same time.
Single-point pressure refuelling, to a maximum capacity of 6,420kg (14,100lb), can be accomplished without accessing the cockpit. Gravity refuelling is possible through overwing caps, but total fuel is reduced to 5,900kg.
Noise from the tail-mounted auxiliary power unit (APU) was low enough when forward of the wing to conduct conversation at normal voice levels. Access to the pressurised, 3m3 (105ft3) rear-fuselage baggage compartment from the ramp is via a door just forward of the left engine inlet. The doorsill is relatively high, and an external ladder or stand is required to easily load items. But the compartment is accessible from the cabin, both on the ground and in flight.
Cabin entry is via an electronically actuated semi-plug-type door with integral steps. The door seal is a static arrangement, not pressure inflated, but an acoustical curtain serves to reduce noise and moderate cabin temperature in flight.
The cockpit features Rockwell Collins Pro Line 21 integrated avionics with four 305 x 255mm (12 x 10in) liquid-crystal displays (LCD) on the forward instrument panel. While the Challenger 300 comes standard with a single flight-management/global-positioning system, our test aircraft was equipped with optional dual systems. Bombardier does not offer an inertial navigation system; instead it uses dual attitude heading/reference systems.
Electronic checklist
The outboard LCDs serve as the primary flight displays (PFD), with an attitude director indicator on the top half and horizontal situation indicator on the bottom half. The inboard LCDs operate as multifunction displays (MFD), with engine indication and crew alerting system, navigation and system synoptics available. A good feature of the MFD is the full-time radio bar along its bottom edge, which shows tuned frequencies. An electronic checklist can be displayed on the right-side MFD, but it is not a "smart" checklist and merely an electronic rendition of the paper one.
Notable by its absence is an overhead panel. In its place is an overhead emergency exit hatch, required since all four cockpit windows are fixed. All system control panels are located on the centre pedestal, and are logically arranged. As with most new aircraft, a quiet dark cockpit philosophy is used to minimise visual and aural clutter.
The manual four-way seat and electrically adjustable rudder pedals allowed me to reach a comfortable seating position. Regardless of the seat's location, the emergency oxygen mask is always readily available, as it is mounted on the outboard shoulder of the seat. Field of view out of the windows was good, and gave a clear view of the winglets, which will aid taxiing in confined ramp spaces.
Pre-start checks were rapidly accomplished, and pneumatic bleed was automatically configured to start the engines using APU air. The start procedure using full-authority digital engine control (FADEC) was essentially automatic, each engine reaching idle RPM within 40s of start initiation. Nose-wheel steering (NWS) was engaged by a forward instrument-panel switch before advancing the power to taxi for take-off. The NWS tiller gives ±65% of motion, and allowed easy negotiation of 90% turns. The rudder pedals give ±7% of motion, more than sufficient to track centreline on the straight portions of the taxi.
Grabman set the flaps to "20" in preparation for a maximum power take-off. The APU was left running for the take-off. While using APU bleed to pressurise the aircraft slightly decreased the take-off roll, more significantly it provided more conditioned air than the engines would have.
Once cleared for take-off, I advanced both throttles to the take-off detent. The FADECs stabilised the engines at a N1 of 86.2%. Acceleration was brisk as the 14,810kg aircraft (maximum take-off weight is 17,460kg) rolled down the runway. Grabman called "V1" and "Rotate" at 116kt (215km/h) indicated airspeed.
Yoke forces were light as I established a 12% nose-high climb attitude. The yoke-mounted pitch trim rapidly relieved forces during gear and flap retraction as the aircraft accelerated to the initial climb speed of 250kt, where the throttles were retarded to the climb detent.
Passing 5,000ft above ground level, I engaged the autopilot in flight-level change pitch and heading-select roll modes, using a glareshield-mounted switch. The throttles stayed in the climb detent as the FADECs maintained the optimum climb N1. During the climb, air traffic control gave us numerous turns and several intermediate level-offs. During these manoeuvres the autopilot adeptly tracked the required headings and altitudes.
Exciting roll
At an ATC-directed level off at FL310 (31,000ft) I turned the yaw damper off, and used symmetric rudder inputs to excite Dutch roll. The resulting motion was undamped, with lots of roll. A series of well-timed rudder and aileron inputs were able to damp out the motions. Motions from the same rudder input with the yaw damper on were quickly damped out. While dispatch with the yaw damper inoperative is allowed, the aircraft is limited to operations at or below FL310, well below its ceiling of FL450.
Passing FL350, a climb Mach of 0.75 was held until levelling off at FL410. Total time to altitude from brake release, exclusive of intermediate level-offs, was 13min. For a maximum gross-weight aircraft on a standard day, Bombardier projects a time to FL410 of 18min and a fuel burn of 455kg. This ability to climb directly to FL410 quickly gets the Challenger 300 above most weather and the majority of opposing air traffic, greatly increasing the probability of getting direct routing to the destination.
Level at FL410, the throttles were left in the climb detent to allow the aircraft to accelerate to its normal cruise speed of M0.8. Reaching M0.8, the throttles were retarded to maintain that speed. I found the trend arrow on the PFD's airspeed tape greatly eased the task. At 236kt indicated air speed, the 14,330kg aircraft held a true airspeed of 445kt, with a total fuel flow of 680kg/h. Pushing the throttles up accelerated the aircraft to the maximum operating Mach number of 0.83 and an airspeed of 247kt indicated/465kt true, where the total fuel burn was 875kg/h.
At M0.83, I rolled the aircraft into a 45% angle-of-bank turn, a manoeuvre that you would not even attempt in the older classic Learjets. Roll control forces were moderate, and there was no perceptible airframe buffet during the turn. Rolling to 60% bank it took a little more yoke backpressure to maintain level flight and there was moderate airframe buffet during the turn. Rolling the aircraft wings level and slowing it to M0.8, I re-engaged the autopilot.
At M0.8 I engaged the "Mach hold" feature of the FADEC. This allows the FADEC about ±3% N1 authority about the set throttle position to maintain a constant Mach. The throttles remained stationary while the FADEC kept the aircraft at the desired cruise speed. During the flight I had been wearing a noise-cancelling headset; taking it off in preparation for visiting the passenger cabin revealed flightdeck noise to be remarkably low.
The test aircraft's developmental cabin interior was only partially complete, lacking seats and tables. At M0.8 I found the noise level to be fairly low in the mid-fuselage portion, increasing slightly forward near the entry door and aft towards the engines. Cabin deck angle was approximately 1° nose up, allowing for easy movement throughout the cabin. The Challenger 300 has a single air-conditioning pack, identical to those in the Global Express. The lone pack maintained a comfortable temperature and a cabin altitude of 7,400ft. Should the pack fail, an auxiliary pressurisation system allows the flight to continue at altitudes of up to 35,000ft.
Back in the left seat, I disengaged the autopilot with the yoke-mounted switch and then cancelled the FADEC Mach hold function by slightly retarding the throttles. I pushed the nose over to establish a 10% dive and the aircraft accelerated to M0.83. As in level flight, there was no airframe buffet at Mmo. In the dive I made a sharp control input in each axis. Aircraft response in all cases was well damped.
Still at M0.83, I pulled the speed-brake lever to its full aft position. Around 10kg of forward yoke force was required to counter the resultant nose-up motion, as the rate of descent exceeded 5,000ft/min. The Challenger's descent was continued to 15,000ft above mean sea level, where I planned to evaluate the aircraft's slow-speed handling characteristics.
Slowing to set up for two stalls I was able to further evaluate the Challenger 300's roll characteristics. Unlike the hydraulically actuated rudder and elevators, the ailerons are unpowered. Roll control authority is enhanced by two hydraulically actuated fly-by-wire spoilers on each wing. While the control yokes are normally tied together, the first officer's yoke displacement determines aileron deflection and the captain's yoke controls roll spoiler deployment. In the event of jammed controls, the yokes can easily be decoupled by pressing a thumb catch switch on the captain's control column. Once decoupled, the captain can maintain roll control solely by using the spoilers.
At 250kt indicated airspeed I found roll control with spoilers alone to be good. After reconnecting the yokes to restore full roll control, I slowed the aircraft to 200kt. Half deflection of the yoke gave a roll rate of about 12%/s during 30%-bank to 30%-bank rolls. Full yoke deflections revealed a fairly linear roll response as the roll rate roughly doubled to 25%/s. At yoke deflections of over three-quarters maximum, however, the unpowered nature of the ailerons was revealed by a slight buzzing feedback in the yoke caused by aerodynamic separation at the control surface.
Approach to stall
For the clean-configuration approach to stall I levelled the wing and continued to slow the aircraft by around 1kt/s at idle power. As the 13,950kg aircraft slowed through 140kt, I stopped trimming in the pitch axis. There were no natural aerodynamic cues to alert to pilot before "stall" was annunciated and the stick-shaker activated at 124kt. Control effectiveness in all three axes was good at the shaker activation speed. Releasing yoke backpressure allowed the aircraft to fly out of the stall and return to normal flight.
The gear was lowered and flaps set to "30" in preparation for a landing-configuration stall. Flap extension did cause light airframe buffet and a power setting above idle was required to maintain a level-flight deceleration rate of 1kt/s. I stopped trimming as the aircraft slowed through the VREF speed of 117kt. The stick shaker and aural "stall" warning activated at 103kt. Again, control effectiveness was good and recovery was effected by relaxing yoke backpressure.
Gear and flaps were retracted in the descent for our return to Wichita. Grabman programmed the flight management system for an instrument landing system (ILS) approach to runway 1L. A good feature of the avionics suite is that it automatically tunes the ILS receiver for the approach. Having burned less than 100kg of fuel since the first approach to stall, VREF for a flaps "30" approach was still 117kt. The flight director (FD) was armed to capture the localiser and glideslope, and I followed its guidance to hold a constant heading and altitude. Depending on pilot preference flight-director guidance can be displayed as either a "V" bar or split cues, another good feature of the avionics package.
Gear and flap extension on final approach, before glideslope capture, caused little change in pitch control forces as the aircraft slowed to 117kt. Once established on the glideslope, roughly 57% N1 was required to maintain VREF, while the airspeed trend vector allowed me to control approach speed accurately. During the approach I found the FD guidance easy to follow.
At 35ft radar altitude I retarded both throttles to idle. At about 5ft above the runway I pulled slightly aft on the yoke, raising the nose 2-3% from the level approach attitude, for a subtle flare manoeuvre. The aircraft touched down softly, no doubt aided by the trailing-link main gear, about 600m from the approach end of the runway.
Grabman set the flaps to "20" and I advanced the power to the take-off detent for a touch and go. He called "Rotate" at 117kt, our approach speed. Once airborne with the gear still down, Grabman pulled the left throttle to idle to simulate an engine failure. At 132kt, around V2 +10kt, I needed 25kg of rudder force and 80% rudder displacement to maintain co-ordinated flight. The centre pedestal-mounted rudder trim was sufficient to zero out pedal forces.
Configuration for the simulated single-engine approach was flaps "30", the same as with two engines. On final approach an N1 of about 63% was required on the right engine to hold the VREF, of 117kt. With the rudder trim centred only 2kg of pedal force was needed to maintain wings-level flight while tracking the localiser. On this approach I waited until 20ft radar altitude to retard the good engine to idle. Again a subtle flare was initiated a few feet above the runway, resulting in another soft touchdown.Easy landing
Once on the ground, with wheel spin-up, the two roll and two ground spoilers on each side automatically deployed. I raised the throttle finger lifts and engaged the hydraulically actuated thrust reversers. As the engines spooled up, I applied moderate pressure on the toe-actuated carbon main-gear brakes. Keeping a steady pressure, not enough to trigger the anti-skid system, slowed the Challenger 300 to below 60kt (6kt of headwind) in less than 5s, just as the thrust reversers were fully deploying. Since there was still 1,000m until the runway turn-off point, I stowed the thrust reversers and released the toe brakes. Taxi back to the ramp, shut down and post-flight procedures were easily accomplished.
During the 1h 20min flight (1 hour 34 min block-to-block) I found the Challenger 300's handling qualities to be quite good, and its Pro Line 21 avionics suite eased flight management tasks while increasing situational awareness. Its ability to climb directly to FL410 should get the aircraft above most other traffic, while its 5,740km (3,100nm) range gives the Challenger 300 true US transcontinental capability. The voluminous cabin and M0.8 cruise speed should make even the longest flights enjoyable for eight passengers.
Based on lessons learned from previous programmes and direct feedback from customers, Bombardier has sought to smooth the Challenger 300's entry into service by refining maintenance procedures, enhancing technical support and ensuring adequate spares are in the field. Service entry is with the company's own Flexjet fractional programme, where annual utilisation rates will be twice those of typical corporate operators. This should provide the manufacturer with an early opportunity to discover and resolve any problems.
While a capable aircraft in its own right, the Challenger 300's strong suit is its value. Compared to its super mid-size competitors, the aircraft offers a spacious cabin at a smaller acquisition cost, typically $17.4 million. Bombardier projects the savings to continue as the Challenger 300's hourly direct operating costs should be lower than any of its competitors. With the Challenger 300, Bombardier has staked a claim to providing the most jet for the least money in the crowded super mid-size class.
Source: Flight International
