Peter Henley/Blackbushe
RAYTHEON AIRCRAFT has made a success of acquiring an existing aircraft type from another manufacturer, refining its design and marketing it energetically. Examples include the Raytheon Pilatus PC-9 MkII and the Hawker 800 XP. Another is Raytheon's Beechjet 400A, which started life as the Mitsubishi Diamond.
Initially, Raytheon was content with the sales rights secured in 1985, assembling the aircraft from kits made by Mitsubishi. By 1989, the tooling had been moved from Japan to Wichita in Kansas in the USA, together with all engineering and manufacturing rights. A US Air Force requirement for a tanker-pilot-training aircraft was met by Raytheon's T-1A Jayhawk derivative of the Diamond, which takes graduates from the T-37 trainer and prepares them for the US Air Force tanker force. This contract was worth 180 Jayhawks to Raytheon and deliveries are still taking place, with a finishing date of 1997.
The Diamond appealed to Raytheon because of the competence of its design and characteristics such as its vertical oval cabin cross-section, which made it a comfortable fit within the Beech family. There was no light jet in the Beech range to which King Air operators could move up, and Raytheon's policy of focusing on cabin comfort bestowed considerable appeal to a modified, luxuriously equipped, version of the Diamond. Raytheon clearly regarded the Diamond as a good design, which was ripe for development and believed that the Raytheon style of marketing would make it a world leader in its class. Ed Berger, Raytheon's manager, Beechjet product marketing, puts the company's marketing policy for the 400A in clear perspective when he says: "The emphasis is on the guy in the back," and that "-speed and performance, combined with comfort, is where this aeroplane shines".
SMOOTH TRANSITION
The idea is that a busy company executive can move from the luxurious efficiency of his or her office to the cabin of the 400A and into a micro recreation of their office. This approach to equipping the aircraft does not stop at cossetting passengers by means of deeply upholstered, leather-covered armchairs, but extends to lighting, air conditioning and business tools such as an Air-show flat screen for video or personal-computer use and a compact-disc player to complement the cabin's audio system.
Beech brought an example of its latest 400A to the UK Farnborough air show in September, giving Flight International a chance to fly the aircraft. Berger, himself a 400A pilot, was joined by Mahlone Becker, chief pilot for jet demonstrations. She and Berger were keen for me to witness the performance, luxury and quietness of the aircraft in the climb to 40,000ft (12,200m) and in the cruise once there. The planned flight therefore consisted of a climb to FL40, a cruise followed by a descent to middle levels for handling, a brief visit to Southampton for an approach and circuit and a return to Beech's temporary home at Blackbushe.
On the ramp, the Beechjet looks a neat little aircraft but, as is to be expected with a small business-jet, it does not have an auxiliary power unit and is therefore dependent upon ground power for air conditioning before engine start, although the on-board batteries are robust enough to start the engines.
The aircraft door, just forward of the port wing, is easy to use and has integral steps which fold in and out automatically and take up remarkably little room within the cabin when the door is closed. Interior headroom (at 1.44m) is strictly limited, but the floor is level (without a central "trench") and, because of the attention focused on furnishings, the cabin has an air of spaciousness and light, flattering to its modest overall size. Climbing into the pilots' seats (and out again) is not easy because of the smallness of the cockpit.
ACCOMMODATING ALL TYPES
To assist the tall, the portly and the clumsy, Raytheon has fitted an overhead strap in the cabin roof and, to limit the damage such people might cause to the centre console, has provided a clever fold-away cover for the aft-part of the pedestal. In addition to protecting the equipment fitted there, it can be used as a seat, a table, or a foot rest. Once the seat had been gained, it proved to be comfortable enough; it had the usual inventory of five-point harness, fore and aft and vertical adjustment, lumbar support and comfortable armrests - but no true recline for the seat back. The whole seat can be rocked through limited travel, but I found that I could not achieve the amount of recline I would have liked. Much thought has gone into the development of the cockpit, but, because of the 400's modest size, it is limited to 2.68m3 (95ft3), with a width of less than 1.5m, and is verging on the cramped. There is little room for documents and no stowage for flight bags. A real strength of the cockpit is, however, its excellent field of view, the unusually shaped side windows affording sideways view even in turns at angles of bank up to 45°.
Electrical control is consigned to a panel in the roof, which exhibits an amazing display of different switch types - toggle, latched toggle, rocker and rotary, all commendably clear in their labelling, which have white legends on a black background. This panel has jurisdiction over the two generators, the ignition, jet pumps, booster pumps, anti and de-icing, heating, lighting.
The Collins avionics installation is comprehensive. Each pilot has a three-tube display consisting of a cathode-ray tube for the primary flight display (PFD) another for the multi-function display (MFD) and a sensor display unit - a smaller CRT which can display radio-magnetic indicator, very low-frequency, VHF omni-directional radio range and distance-measuring equipment information to choice.
DISPLAY UNITS
Each PFD has attitude, airspeed and altitude in the upper portion and horizontal situation information below it. There are two control display units (CDUs) at the forward end of the centre console. Each is accessible to either pilot. These CDUs control the PFDs, MFDs and radar. There is a full suite of navigational and communications equipment, including traffic-alert and collision-avoidance system. A set of three standby instruments (airspeed indicator, altimeter and attitude) is above the first pilot's MFD.
Power to start the engines comes from the aircraft's 24V, 40A/h lead-acid battery or from an external 28V direct-current source through a socket on the aft starboard fuselage. A ground-power-unit start is recommended in ambient temperatures of -15°C or below. The before-start checks can be completed some time before the planned departure time to enable engine starting as soon as the passengers have boarded. The Pratt & Whitney JT15D-5 engines of 13kN (2,965lb) take-off thrust each, have what was described to me as a "smart-start" system.
This, however, seemed to fall short of the automatic starting, including shut-down if a malfunction occurs, already available on state-of-the-art turbofans. With the 400A, the engine fuel-controls have to be switched on, the start selection made to left or right, the start button pressed, the thrust lever moved to idle at 8% N2, and the instruments monitored for inter-stage turbine temperatures and starter disengagement. Engine behaviour is displayed on a central panel, having five instruments for each engine arranged in two vertical columns - the left column for the left engine and the right for the right engine. The instruments are predominately analogue, but indicators such as those for turbine and fan RPM have simultaneous analogue and digital displays.
Taxiing the 400A is straightforward. The hydraulic wheel brakes have anti-skid and are applied through toe action on the rudder pedals. The parking-brake handle is located under the lower left side of the instrument panel. To set the parking brakes, the handle is pulled out and the toe brakes pressed two or three times. Nose-wheel steering is via the rudder pedals, the authority of the pedals extending only through 25° left or right, an additional 20° being available either way by using differential brake and asymmetric thrust. The engine thrust-reversers are checked while taxiing. These are hydraulically operated and selected by putting the reverser levers mounted on the thrust levers up and back at the idle position, thus deploying the reverser doors which redirect the exhaust gases forward, over and under the engine nacelle. On the first flight of the day, the engine fuel-controls should be checked. The procedure for this is slightly laborious, requiring 66% N2 compressor speed to be set, the check switch to be pressed followed by thrust to idle and a check that the N2 recovers to 52% when the switch is selected off.
The aircraft was lightly loaded, having no passengers (the maximum permitted is nine) or baggage, but had 1,590kg of fuel distributed between the wing and forward fuselage tanks (1.270kg) and the fuselage rear tank (320kg). Fuel in the 400A is contained in a plethora of tanks - two centre-section bladder tanks, two wet wing-tanks, two under floor bladder-tanks, and two aft-fuselage bladder tanks holding a total of 2,230kg of useable fuel. Refuelling is via three fillers, two over the wing and one above the starboard engine. Fuel quantity is indicated by a two-pointer gauge for the two wing tank groups and another indicator for the fuselage tank group. Fuel can be cross-fed in flight to equalise the fuel between wings.
PRE TAKE-OFF CHECKS
The all-up weight (AUW) for take-off was 6,675kg (against a maximum permitted of 7,310kg). The weather at Blackbushe was good, dry visual meteorological conditions, with little wind and the temperature 15°C, QNH 1020mb. Runway 26 is 1,340m long and the airfield is 330ft above sea level. The pre-take-off checks were completed from the electronic checklist displayed on a multi-function display. Flap was set to 10°. The 400A, has Fowler flaps, which occupy almost the full wingspan (made possible because roll control is by spoilers). The flaps are electronically selected through a lever on the centre console and hydraulically operated. The positions are 10°, 20° and 30°, flap up and the first two down settings being used for take off as required by weight and field performance considerations. On this occasion, take-off was with the flaps to10°, and the ECS (engine bleeds) on; the speeds were V1 101kt, VR 108kt, V2 114kt (210km/h). The technique for take-off is to set the power to about 90% N1 against the brakes. During acceleration, and before 80kt, the non-flying pilot refines the power set to the precise take-off thrust. The aircraft was easy to keep straight, using nose-wheel steering initially, then rudder. Rotation and establishing the climb attitude of about 13° nose-up were straightforward; retraction of the gear and flaps produced innocuous pitch changes.
As the take-off had been with the engine bleeds on, there was no airborne initiation of the pressurisation and there was no pressurisation surge - but a bleeds-off departure was not undertaken during the flight and I therefore had no experience of switching on the bleeds during the climb. Once airborne, the yaw damper was selected on and the engine thrust set for the climb; the engine synchronisation was put on (it must be off for take off and landing and can be selected to synchronise either fan or turbine as required). Throughout, the flight-director information had been easy to read, including the tape airspeed and altitude displays. The aircraft settled into a comfortable climb at 250kt and 3,000ft/min (1.52m/s).
All the 400A's primary flying controls are mechanically operated. Pitch control is exercised through the elevators, while pitch trim uses electrical operation of the variable-incidence tail-plane. Roll control is via the spoilers with two trim tabs outboard of the flaps on each wing trailing edge to provide roll trim. The spoilers have inboard and outboard portions on each wing upper surface and double as the airbrakes - in which mode they are electrically selected and hydraulically and mechanically operated.
CONVENTIONAL CONTROL YOKES
The control yokes are conventional, with a "coolie's hat" trim switch for pitch and roll. Rudder trim is through a control console mounted trim wheel. I found the pitch trim irksome to use for relieving even relatively small control loads. There is a yaw damper switch on the auto-pilot panel and the damper is normally switched on in flight regardless of whether the auto-pilot is to be used. The yaw damper was effective at its job, but, when switched off, rudder-induced Dutch rolling was marked with little natural damping; I was told that use of the yaw damper is mandatory above 28,000ft. Control harmonisation was good and the control forces congenial. Roll control through the spoilers was as if by ailerons; there was no discernable yaw with spoiler deflection (yaw damper in).
As FL40 was approached, the rate of climb was still 1,200ft/min and the handling of the aircraft still crisp and responsive. The attention to cabin detail - Nomex sound insulation, particularly in the rear fuselage, and Lord fluid-elastic engine mounts - has certainly paid dividends.
Dropping back to middle levels, a rate of descent of 5,000ft/min was achieved with the throttles closed and airbrakes out at 250kt. The airbrakes, selected by a lever on the centre console, provoked only slight pitch changes, with no buffet, but there was some aerodynamic noise. Because the airbrakes are the roll-control spoilers, deployed symmetrically, there is some loss of roll authority when they are out and roll control required noticeably higher control wheel forces. The airbrakes are either in or out with no intermediate settings. At 15,000ft, the aircraft handled pleasantly with harmonised control forces in pitch roll and yaw (yaw damper on and airbrakes in). The AUW for stalling was 6,100kg ,and the predicted clean speeds were 127kt trim and 105kt for the stick shaker.
WARNING SYSTEMS
The aircraft has a stall-warning system, which includes stall annunciators and aural signals to headphones and speakers and a control-column shaker to simulate airframe buffet; there is not a stick pusher. There is also an angle-of-attack (AoA) indicator and, when the stick shakers operate, igniters are activated in the engines to guard against high-AoA flameouts. Approach to the stall warning was routine and predictable, with good aileron and rudder control; the aircraft can be flown out of the stick-shaker regime by applying full power with little loss of height.
Next, a coupled instrument-landing-system approach to runway 20 at Southampton was flown. All the modes tried (altitude hold, heading, tracking and localiser/glideslope) were smooth and accurate, while localiser capture from about a 60í intercept was good. Airspeed was easily controlled on the glideslope with power. The 400A's limiting speeds of 200kt for the gear and flaps (to take-off and approach) and 170kt (to land flap) allow speeds to be kept up in the instrument pattern and visual circuit when time or air-traffic control requirements dictate.
After a full-stop landing at Southampton and a back track for departure, an engine failure after take-off was simulated by throttling back the starboard engine at V2 and 10° flap. The aircraft continued with a healthy rate of climb as expected, but some into-live-engine rudder and aileron were required to maintain heading.
The 400A has a rudder-booster system employing bleed air, but it relieves the pilot of about 75% of foot force rather than providing full yaw compensation. I had wished to experience an engine cut at about 2,000ft and a subsequent airborne relight, but Becker was not happy with this and preferred the simulated procedure. Airborne relights are possible up to 35,000ft, between 100kt and 250kt using starter-motor assistance, or between 200kt and 250kt using the windmill procedure, according to the aircraft manual.
It is evident that Raytheon has done exactly what it claims and has taken care of the "guy in the back" and it equally clearly is, as Berger says, that in terms of speed, performance and comfort that the 400A is at its best. Vmo (maximum permitted speed) is 320kt, or 0.78M above 11,000ft, but only 264kt below 8,000ft, however, at levels between 35,000ft and 34,000ft. The book shows cruise speeds in true air speed of about 450kt, with a useful 3,100km (1,690nm) long-range cruise at 45,000ft.
The take-off field length at maximum AUW and the landing distance required at maximum landing weight are both under 4,000ft at sea level/indicated airspeed. It is in all-round performance, rather than at high speed, that the 400 does well. The comfort of the cabin, including noise levels, is beyond dispute and the Rockwell-Collins avionics and Pro Line 4 flight-control system endow the aircraft with a go-anywhere sophistication. In my view, however, that level of sophistication is not matched in some of the basic aircraft systems - the dated electrical-control panel, the multi-tank fuel system without single-point refuelling, lack of automatic engine start or electronic engine management, for example.
Despite these reservations, the Beechjet 400A is an excellent and competent aircraft and pleasant and fun to fly. Its ultimate appeal is as an airborne limousine for busy executives.
Source: Flight International
