Beyond the Horizon—The Hawker 4000

By Geoff Cooper.

The Hawker 4000 (nee Horizon) super mid-size business jet has been a long time in the design, construction and certification process. It is the largest aircraft in the Hawker family to date—69’6” long with a wingspan of 61’9” and standing almost 20’ tall. Design of the aircraft began in 1993 and the aircraft made its maiden flight in August 2001. However, it did not gain initial type certification until December 2004.

Final type certification followed in November 2006, but modifications required additional certification and this was achieved with the first production model in June 2008. The company can be excused for this prolonged gestation period, with the Premier 1 and T-6 Texan II in development simultaneously, and a rebranding and change of owner, all taking place in the intervening years.

The wait has definitely been worth it. This “typically Hawker” jet—albeit with a new T-tail design—would make any owner stand proud and every FBO very happy to have it parked centre-stage on its ramp. First appearances count, and the exterior finish is superb and very worthy of the praise it attracts.

The fuselage is built by Hawker (Wichita) in three sections on an aluminium mandrel sized to the interior cabin dimension. It is all-composite construction using graphite/epoxy materials with a honeycomb core and results in superior strength together with the advantage of lighter weight. Laying up is by machine to very fine tolerances and the finished product—with fuselage walls approximately an inch thick—is then baked in an autoclave for around eight hours at 175°C.

The wings (manufactured by Fuji in Japan) are all-metal construction with single-piece top and bottom skins, while the tail surfaces all have aluminium spars and ribs with composite skins. The only imperfections to the surface of the supercritical wings are single rows of very small vortex generators on the upper surfaces ahead of the ailerons to prevent flutter at “very high speeds”.

Various flush fairings/doors around the wing centre section and fuselage house single-point refuelling, potable water refill, lavatory servicing, AC/DC power receptacles, landing/taxi lights and maintenance access. The tail cone houses the Honeywell auxiliary power unit, which is available for all services on the ground and as a backup electrical supply in the air.

Towards the rear on the left hand side of the fuselage is the access door to the rear stowage compartment, which is conveniently located at a level that is easily accessible from the outside. With a volume of 89 ft3, the heated and pressurised baggage area can carry up to 900 lbs.

Access to the cabin is via an integral set of steps with a comfortably gradual gradient. The steps feature two cleverly designed compartments intended to house all those bits and pieces that pilots must “remove before flight” to ensure a safe operation. Night lighting is provided for the stairs, which have both internal and external operating switches for the crew.

Located at both sides of the door inside the cabin are closets—ideally positioned to place one’s Armani suits or Versace gowns inside as one steps aboard—keeping them crease-free throughout one’s lengthy journey.

Step into the main cabin and the first obvious impression is space—lots of it. With a flat-floor stand-up height of six feet, a length of 25 feet and width of 6’ 5.5”, the 867 ft3 cabin has ample room for the four pairs of club seats fitted to the demonstrator aircraft—with room for another four seats if desired. An optional three-seat divan is available to replace the right hand rear club setup.

The seats are plush leather with arm rests and fully adjustable, as one might imagine, with recline and rotate functions, and are complemented by full size pullout writing tables. The cabin features a DVD entertainment system, LED lighting and twin Rockwell Collins (Series 4000) air-show screens that provide a truly informative presentation.

A Passenger Service Unit (PSU) located above each seat unit contains typical airline type oxygen masks in case of the event of depressurisation.

Dual engine driven air cycle units—one each for the flight deck and cabin—provide conditioned air at a maximum differential of 9.6 psi, which can maintain a comfortable cabin altitude of just 6000’ at FL450—far superior to most current commercial airliners. A gaseous oxygen system provides sufficient supply for all on board in the event of an emergency and the crew positions have diluter demand masks with smoke goggles.

In the rear of the cabin, a sliding door provides access to the lavatory facilities and full vanity unit. In-flight access to the baggage hold (at altitudes up to 35,000 feet) is also available through this cubicle.

At the front of the cabin, a fully equipped galley occupies the right hand side adjacent to the entry door. Standard features include a microwave oven, coffee maker and hot/cold water supply, with variations available on request.

Beyond the galley, in the business end of this business jet, the forward panel layout dominates one’s first glimpse of the flight deck. The full Honeywell Primus avionics suite incorporates five substantial colour LCD screens: two primary flight displays (PFDs), two multi-function displays (MFDs) and a central Engine Indicating and Crew Alerting System (EICAS); all the big jet gear—and more.

The centre console houses dual multifunction control display units (MCDUs) and most of those other very important “need to be close at hand” controls: power levers/autothrottles, flap selector, speed brake, park brake, trims, engine start and gust lock.

Along the sidewall adjacent to the captain’s seat, a flat panel houses the audio selector panel (ASP), the nosewheel steering tiller and a cursor control device (CCD)—very similar to the one in the B777—for manipulating the MCDU. The co-pilot’s station is similar but without the nosewheel steering capability.

The crew seats recline and are adjustable fore, aft, and vertically. Armrests, headrests and lumbar support contribute to ensuring maximum comfort.

Rams-horn control columns integrate nicely with the contour of the instrument panel coaming which houses each pilot’s PFD controller and the Flight Guidance Controller.

The forward windscreens are single-curvature pieces and the side windows double-curvature. All are electrically heated (as are the large cabin windows) through conductive layers within the assembly, negating any requirement for defogging. The windscreens’ exteriors are treated with a rain repellent coating, eliminating the need for wipers and retaining the sleek, clean lines of the exterior forward flight deck.

The overhead panel between the pilots contains systems controls and lighting switches. Everything is logically located for intuitive selection and, as with almost every modern aircraft, is of the “set and forget” type. Typically, lights are extinguished during normal operation, and any abnormal condition will result in visual and audible signals being displayed on the caution panels and EICAS display unit.

The standard avionics suite makes for impressive reading. While one might expect this in an aircraft with trans-Atlantic approval, the Hawker 4000 features a significantly higher “standard” fit than its competitors and indeed, some of the Hawker’s features are not even available as options in competing aircraft whose “base” prices are already higher than the Hawker. In the Hawker 4000, all primary nav/comm units (GPS, INS, VOR, DME, VHF) and the FMS are duplicated and, with the total integration of the flight controls—auto-pilot and dual auto throttle—crew workload and fatigue levels are significantly reduced.

Propulsion for the Hawker 4000 is provided by twin tail-mounted Pratt & Whitney Canada PW308A high-bypass twin-spool turbofan engines, each delivering 6,900 lbs of thrust. Hot-and-high performance is retained with a flat rating to ISA +22°C, which enables normal departures from many of the more challenging airfields around the globe. Additional systems on the accessory gearbox include AC generator drive, hydraulic pump and bleed air sources for engine starting, anti-ice, air-conditioning and pressurisation.

Engine thrust management is controlled by typically modern methods, with a full authority digital electronic control (FADEC) incorporating the thrust lever, electronic engine control (EEC) and fuel control unit (FCU). All work nicely in unison in response to the pilot’s demand for power via the thrust lever position. This sets and regulates fuel flows and engine protection parameters via electrical commands, further easing the flight deck focus, particularly during critical phases of flight when pilots would rather not have to direct their concentration towards setting exacting criteria.

The TBO (time between overhaul) on the engines is a very respectable 6,000 hours, and a diagnostics unit monitors and records engine data and faults—either automatically or in response to pilot selection. Recorded data is then analysed by ground based computer software. This has been a regulatory requirement for aircraft operating on ETOPs (extended range twin engine operations) for many years, and has proved extremely beneficial in identifying and addressing otherwise minor performance deterioration that might well have become significant. Hydraulically operated Nordam “bucket” type thrust reversers complete this dynamic engine package.
Dual independent hydraulic systems operating at a typical 3000 psi power the nosewheel steering, landing gear, wheel brakes, parking brakes, spoilers, rudder and emergency rudder control, and standby electrical generator (HDMG)—another requirement of ETOP’s flying. A power transfer unit ensures full systems operation in the event that either of the engine driven pumps should fail.

Anti-icing (which prevents ice accumulation, as opposed to de-icing, which removes ice that has accumulated) for the wing leading edges is designed to be “evaporative”—pressure and temperature-controlled bleed air is distributed along the surface by piccolo tubes to prevent any ice accumulation. The supercritical design/laminar flow wing is highly dependent on the surface remaining “clean”, which cannot be achieved with de-icing where the result is often “flow back” and an uneven surface. The horizontal stabiliser features a unique de-icing system referred to as “thumpers”—an electromagnetic expulsive system that is used to break any ice accretion away.

This is almost entirely an AC aeroplane. Two engine-driven AC generators—either of which is individually capable of picking up the total electrical load—supply normal electrical requirements. The APU is available up to 34,000 feet in the event that both main generators should fail. The HDMG will do likewise in the event of total loss of AC and DC power.

There is some DC power available, of course. Two conventional 28-volt lead-acid batteries are fitted to start the APU (which then provides the AC power to the transformer rectifier units [TRUs] that convert the AC to DC to charge the batteries!) The fact that the flap system also utilises DC power for its operation prevents this from being a comic paradox. An external power input is available for both sources.

Primary flight controls are a mix of conventional and “fly-by-wire” systems. These are naturally interlinked to provide a common status to both pilots but are capable of independent and single-source operation if required. Secondary controls include horizontal stabiliser trim and spoilers, which have multiple functions—assisting with roll and speed control in flight and as “lift dumpers” on the ground.

All systems are fitted with servo tabs and variable differential transformers—both linear and rotary—to provide feedback on control surface position and relay information to the autopilot servos. Standard equipment includes a rudder ratio/feel unit, yaw damper, stall warning protection and stick shaker.

The four-segment flap panels are set to any one of three positions—12°, 20° or 35°—by mechanical drive from the power drive unit. The system incorporates multiple safety features to protect against asymmetry, torque overload or failure of the mechanical drives.

Performance is where the Hawker 4000 really excels and this new aircraft maintains a long recognised company tradition of “fill the seats, fill the tanks and let’s go”. It also makes it a class leader amongst its competitors—the Gulfstream G200 and the Challenger 300.

With a zero-fuel weight of 23,500 lb, maximum payload of 2,500 lb, maximum fuel capacity of 14,600 lb and a maximum takeoff weight of 39,500 lb, this aircraft has been designed with long range flights in mind. Capable of climbing to FL370 in 14 minutes, and with a certified ceiling of FL450, the Hawker 4000 will fly at speeds ranging from M.78 (LRC) to M.84 (MMO), with M.82 being the standard high speed cruise.

Its range (with IFR reserves) with a typical load of six passengers varies from 2,950 nm at M.82 to 3,175 nm at M.78—so minimal, in real terms, that high speed cruise of M.82 is standard operating procedure.

At sea level on a standard day, with the same load of six passengers, the aircraft will get airborne from 5,000 ft runway and fly 3,000 nm. Increase the temperature to ISA+15°C and the required runway length only increases by around 250 ft.

For example, were one to take one’s family skiing in Aspen for the weekend (as one does in one’s Hawker 4000), one could depart this airfield (7,006 ft runway at 7,820 ft ASL) and fly 2,210 nm at high speed.

At a maximum landing weight of 33,500 lb, this aircraft requires just 3,000 ft of runway for landing. These are amazing figures for a “biz-jet” of this size.

When this writer joined the Hawker 4000 demonstration crew aboard the aircraft in Sydney recently for its Pacific “launch” demonstration, it rapidly became apparent that this was an exceptional aircraft. Start-up was simple and brief, while the taxi was very quiet and smooth; taxiway undulations were barely noticeable through the trailing link undercarriage. Idle power was more than sufficient to break away with eight passengers and 7,000 lb of fuel on board, and the 70° of nose wheel deflection made it obvious that access to and from even the most congested tarmacs would be a breeze.

Departure was from Sydney’s RWY 34R into a very light northerly. The acceleration was quite astounding and those of us facing rearward in the luxury club seating noticed a distinct trend to slide aft. Climb-out was similarly impressive and, very quickly, the auto-throttles were commanding a thrust reduction to level off at the hold down altitude of 5,000 ft. Once cleared to resume climb, we very soon levelled off at FL260, where noise levels at cruise thrust were extremely quiet as we were given a PowerPoint presentation.

All too soon it was time to return for landing. Extension of the speed-brake created only mild vibration on descent and engine noise was hardly audible. Lining up on the ILS 34R, the automatics commanded a smooth profile as the Hawker’s crew—Scott Rosin and Jay Palm—configured the aircraft for landing.

Again the undercarriage demonstrated its prowess (don’t pilots just love this ego-enhancing gear). The touchdown was very smooth, the spoilers deployed automatically and the crew used only reverse idle to roll out to the far end.

The pilots both described the Hawker 4000 as “a delight to fly”.

Once we were back on the ramp, it was not difficult to rate the quality and performance of this aircraft—simply spectacular! Hawker Beechcraft can be truly proud of this model. Even the most discerning critic would be hard pressed to find fault. This is air travel—beyond the horizon—in class, comfort and style.

The author would like to thank the team at Mascot FBO for the opportunity to participate—it was a pleasure indeed.