The Dornier 228 is now well settled into service1 and orders for 40 aircraft have been received. 24 of them have been delivered. The production line is running at two to three aircraft a month. In addition, India has signed up for 150 228s, eight of which will be delivered complete, 16 in kit form2 and the rest will be made under licence.
The TNT wing is paying off in offering good short-field performance combined with high cruising speed and excellent rate of climb. In fact, the new wing and the high power-to-weight ratio of 8.8 lb/HP are already allowing Dornier to move into higher weights without serious loss of performance.
Certification
A variety of improvements are already being introduced. First of all, the landing weight has been increased from 5,500 kg (12,125 lb) to the same level as maximum take-off weight, 5,700 kg (12,630 lb), so that minimum stage length is no longer determined by the landing weight.
Dornier’s fatigue tests have now reached more than 180,000 flight cycles and the company claims it can now guarantee four lives of 30,000 flight cycles. These tests have shown that the operating weights can be yet further increased without modifications and Dornier should now be obtaining German certification for an increase in take-off weight to 5,980 kg, a landing weight of 5,750 kg and a zero-fuel weight of 5,590 kg. It is now clear that weight increases beyond those already mentioned could be achieved with only minor3 airframe modifications.
Dornier claims that the 228 requires 0.71 maintenance man-hours (that is, actual hands-on time), per flying hour, including 0.1 hours for the engines.
Systems
The 228 is a simple aircraft, even to the extent of being certificated for single-pilot operation for those who want it. The flight controls are all mechanical with minimum complications. Elevator and ailerons are controlled through push-rods which make them light and free of friction. The ailerons droop with the flaps. A light centring spring in the aileron circuit can be offset by an electric motor to apply aileron trim.
The elevator circuit contains a spring giving a permanent nose-down effort to reinforce natural static stability. The surface is mounted on the movable, tailplane, whose electric actuator motor is controlled from conventional twin-gang switches on the aileron wheels. The tailplane motor will stall when the out-of-trim effort becomes equivalent to a pull or push force of 110 lb (50 kg). British certification has required automatic trimming when the flaps are lowered or raised, because the trim change caused by the first five degrees of flap is substantial and in the opposite direction to that expected. The rudder is controlled by cables and has a plain, mechanically actuated trim tab.
The electrical system has two engine-driven generators, two static inverters, two batteries, essential and non-essential buses and an external supply. The fuel system has two boost pumps, two engine cut-offs and a cross-feed switch. The two main tanks in each wing are interconnected and transfer into a feeder tank behind each engine nacelle. Normal refuelling is over-wing, but a low-mounted, single-point pressure refuelling nozzle is optional.
The flaps are electrically operated. A self-contained hydraulic system operates the undercarriage, wheel-brakes and nose-wheel steering. Pressure is raised to about 3,000 lb/in2 (210 bar) by an electric pump as soon as the gear lever is selected down. The system is switched off as soon as the gear is retracted, but some pressure is stored in an accumulator. There is a manual pump for emergency undercarriage lowering. The aircraft can be taxied with brakes and asymmetric throttle if nosewheel steering fails.
The Garrett TPE331-5 engines are flat-rated at 715SHP and top temperature and torque limits are automatically controlled. The full power is maintained at up to ISA +18° at sea level or up to 7,300 ft in ISA. The propellers normally turn at just under 1,600 rev/min. The propeller pitch is also automatically adjusted to prevent reverse thrust if an engine loses power.
The standard flight control system is the King KFC-250, which has an integrated flight director.
At the controls
Pilots should like this aircraft. It has that quality of smooth responsiveness and excellent control harmony which is a trademark of German aircraft design. The stalls are absolutely classically pure and single-engined handling seems to be quite viceless.
3700 знаков
Notes
1. to settle into service – ввести в эксплуатацию
2. in kit form – (зд.) комплектом
3. minor – незначительный
4. smooth responsiveness – плавная управляемость
5. viceless – safe
