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Aviation History
1997
1997 - 1231.PDF
FLIGHT resr Revised and upgraded, and under a new marketing name - the ATR- 72 flies on. XKV^WA- Breath of fresh AI(R) PETER HENLEY/TOULOUSE WHEN AERO INTERNATIONAL (Regional) (AI(R)) was formed in January 1996 from die regional-aircraft businesses of Aerospatiale of France, Alenia of Italy and British Aerospace, its declared policy was to manufacture and market a family of complementary regional aircraft. That family now includes the Jetstream 41 turboprop (with 29-30 seats), the ATR 42 and 72 turboprops (48 and 66 seats), and the two RJ four-engined jet airliners (the RJ85, with 85-92 seats, and the RJ100, with 100-110 seats). The company is keen to review, revise and update its aircraft, and has recently completed a demanding programme to update the ATR 42 and 72. The aim has been to refine both types by incorporating the latest relevant technology, and to increase the commonality between die two. Both models, from inception, had the same type of wing, tail and fuselage - the 72 having a stretched version of the smaller aircraft's fuse lage. Now they share die same engine types and propellers, and commonality is such that pilot type ratings are good for both aircraft, and air line-engineering organisations face far fewer headaches over spares holdings and mainte nance procedures. The newest simulators are even designated "ATR 42/72" and need only an easily accomplished change of instrument panel to represent either version. Both aircraft types have sold well since the 42 was launched in October 1981 - over 500 units to date - although success has not been without its pitfalls. In 1994, an ATR 72 crashed near Roselawn, Indiana, with the loss of all on board. The accident happened in extreme icing condi tions with several exacerbating circumstances. The accident, together with another to a Jetstream, nevertheless led to damaged public The ATR 72-210A is a better aircraft for pilot and passenger. confidence in turboprop airline safety in the USA - and imposed upon Aerospatiale an oner ous responsibility to ensure that the ATR series was more tolerant to icing conditions. While modifications were being undertaken to counter the airframe-icing problem, work was completed by AI(R) to enhance the general appeal of the 42 and 72. The latest versions, the 42-500 and the 72-210A, have the same Pratt & Whitney 127F engine and the same Hamilton Standard HS568F six-bladed propeller. The electrically synchrophased propeller blades are part of the package which AI(R) is incorporating in the 72-210A to make the aircraft quieter, smoother and cheaper to operate. DEALING WITH THE ICE The aftermath of the Roselawn accident revealed that ice could build up on the upper- wing surface behind the leading-edge de-icing boots (but only with supercooled rain drops spreading back over the aerofoil before freez ing) and interfere widi roll control by disrupting the air flow over the ailerons. Wider-chord de- icing boots have been introduced to break up any ice forming behind the leading edge, and spring tab assistance of the ailerons has been incorporated to improve their effectiveness in icing conditions - although the mechanical control runs to the ailerons remain as before. Because of the high-wing configuration of the ATR, it is not possible to see wing-icing from the cockpit bur, as a result of the tests AI(R) has done by flying behind a "water bomber" in icing conditions, guidance to pilots on how to identi fy hazardous conditions from the cockpit has now been provided. In addition to the "commonality" now offered to operators of mixed ATR fleets, AI(R) has aimed to reduce noise and vibration levels in the cabin by cutting noise and vibration at source through the slower rotating, better syn chrophased six-bladed propellers, and by ame liorating noise and vibration through frame damping in the fuselage structure and skin damping to the centre portion of the fuselage. Flight International was able to sample the effectiveness of these modifications during a flight test from AI(R)'s plant in Toulouse, France. The aircraft used was a production 72- 210A. It conforms to die classic mould of high- wing turboprops, with its fuselage sitting comfortably close to the ground on a relatively narrow-track (4.1 m) undercarriage, each of die double-wheeled main legs folding neatly into a pontoon on eidier side of die lower fuselage; die main and nose-wheel doors remain open while the wheels are extended. The high wing ensures that die engines are kept above the worst of airport debris and water spray from contaminated runways, and the 3.8m-diameter propellers are afforded ample ground clearance. The tail-plane is mounted nearly, but not quite, on top of die slighdy swept fin. The primary flying controls are all mechan ically operated and each has a horn balance. Roll control is provided by die ailerons working in synchronisation with an hydraulically powered spoiler on each wing. The trailing-edge flaps have two segments on each wing and are elec trically controlled and hydraulically operated; asymmetric extension protection is provided. The standard aircraft offered by AI(R) has a passenger door widi integral folding steps, aft on the left hand side of the fuselage and a • FLIGHT INTERNATIONAL 7 - 13 May 1997 43
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