Update – ATR42

An increasing number of the longer regional routes are being flown by jet aircraft, which in Western Australia have long since replaced the Friendship. With the upgrading of additional NSW airfields to jet standards, East-West Airlines too will shortly introduce the F. 28 Fellowship on regional routes. In spite of this the majority of the routes operated by the Nation’s regional airlines are (and will remain) typical turboprop routes. By typical turboprop routes we mean routes where the traffic is inadequate to support a jet aircraft at a viable frequency and where the sector distances are short enough to ensure that the journey time differential between jet and turboprop aircraft is small enough to be acceptable to the turboprop passenger. This definition ignores several other factors which could of course dictate the use of a jet aircraft. Nevertheless, the number of these typical turboprop routes in Australia is considerable and is certain to ensure a place for a new-generation turboprop transport in the regional airlines’ future inventories. It seems appropriate therefore to take a look at Europe’s most recent design in this category, the ATR 42, and to comment briefly upon its suitability for Australian operations.

Program Status

Among the front-running contenders for the eventual Fokker Friendship replacement programme is the ATR 42 twin turboprop transport, designed and constructed jointly by Aerospatiale of France and Aeritalia of Italy. The ATR 42 programme was launched by the two companies in October 1981 (on a 50/50 work and cost-sharing basis) and the first aircraft is due to fly in August 1984. The Franco-Italian consortium managing the programme has thus taken advantage of later launch and first flight dates to provide a more advanced design than any of the competitors, knowing that the greater production resources of Aerospatiale and Aeritalia will permit a higher monthly delivery rate. Deliveries to airlines will commence in the second half of 1985.

The ATR 42 programme is today on schedule from both the technical and commercial standpoints. Basic design options were frozen in 1982 and detailed design of many elements including the structure has today been fully completed. Systems design was 90 per cent complete at the end of March 1983 and a similar proportion of the electrical systems drawings will be issued by mid-1983. Computer-aided design and computer-aided manufacture play a major role in this programme.

In developing an aircraft fully tailored to regional carriers’ needs, the design teams in Toulouse and Naples have put an accent on the optimisation of existing technologies, using new technologies and materials only where these are justifiable on grounds of cost-effectiveness. Aerodynamics is a case in point of optimisation of existing technology. Using an airfoil section developed by Aerospatiale, the joint design teams have evolved a very efficient wing having an exceptionally high lift/drag ratio and maximum lift coefficient. With a wing area of only 54. 5 m2, the ATR 42 has optimised take-off, cruise and landing performance, the latter achieved by the use of large double-slotted flaps with fixed slats. For landing these flaps deflect to 60° without rearward movement. This wing will still permit the fuselage stretch to accommodate over 60 passengers, which Aerospatiale/Aeritalia already envisaged. ·

Choice of vendors for major items of equipment has also been made. In addition to Pratt & Whitney Aircraft of Canada and Hamilton Standard for the engine and propeller, the vendors include Messier-Hispano-Bugatti for the landing gears, Sperry and King for the basic avionics, and Softair for the pressurisation system. Orders for initial ship sets of long lead items were placed during the first quarter of 1982. .

A full-size engineering mock-up of the fuselage and flight compartment (built at Aeritalia’s Naples plant) has been available at Aerospatiale’s main Toulouse facility since September 1982. This not only assists design and manufacturing personnel to finalise the layout of the various systems and equipment but also serves to check the accessibility of these items, prior to the availability of the first aircraft for which metal was first cut in August 1982.

Final assembly, flight testing and certification of this first aircraft and all subsequent commercial versions of the ATR 42 will be performed at Aerospatiale’s Toulouse facility, which will also produce the product support.

From the commercial standpoint, there has been an exceptionally good response to the ATR 42 from the many hundreds of airlines and other organisations that have had presentations; the technical excellence of the ATR 42 design has been warmly praised by potential customers who in turn have provided some helpful criticism. These presentations have in many cases been made with the help of a full-size cabin and cockpit mock-up, normally located at Toulouse but available for periodic expositions.

At March 31, 1983, a total of 43 firm orders for the ATR 42 had been received from 14 companies in seven different countries, together with paid options for a further 1 O aircraft. Purchasers include Ransome Airlines, Command Airways and Wright Airlines of the USA, Cimber Air of Denmark, and the Finnish national carrier Finnair, and six customers from France and Italy.

But what of the aircraft itself? With a capacity of 42/49 passengers at a seat pitch of 32/30 inches respectively, the ATR 42 is the largest and most modern of all the new-generation regional transport aircraft. The high-wing layout and large diameter fuselage carrying a sharply raked fin and a high-set tailplane give the ATR 42 a purposeful look. Unconventionally for commercial transport, the twin-wheel main gear is attached directly to two of the main fuselage frames and accommodated in neatly streamlined lateral pods. These also house some of the air conditioning, hydraulic and other systems equipment which are consequently readily accessible on the ground. Great emphasis is being placed on maintainability by the joint FrancoItalian design teams, which include maintenance specialists whose specific task is to ensure that MSG 3 maintainability philosophy is fully applied to the design of the complete aircraft.

Powered by two Pratt & Whitney Aircraft of Canada PW 120 turboprops, each driving a Hamilton Standard SF 14 propeller and giving 1800 shp for take-off, the aeroplane will cruise at 276 kt at altitudes of up to 25,000 feet. This altitude is not limited by the cabin pressurisation system but by the necessity for providing a complete passenger oxygen system above that height. The design range of the basically equipped ATR 42-100 aircraft is 700 nm (1500 km) with 42 passengers and baggage, that of the higher gross weight ATR 42-200 model is 950 nm (1760 km) with 46 passengers and baggage. Summarised details of these two models are given at the end of this article.

The advanced design brings advantages.

From an Australian viewpoint, what distinguishes the ATR 42 from other new-generation transports? The main features of the ATR 42 have been examined from documents recently released by Aerospatiale/Aeritalia and from inspection of the two mockups at Toulouse. They reveal that the ATR 42 offers a number of positive advantages for Australian operations, which are briefly summarised below:

The overall design concept is undoubtedly slanted towards the upper end of the regional market, as demonstrated by the bigger all-round capacity and the greater refinement, particularly in aerodynamic design. These will provide the extra margins of useful load and performance that any aircraft requires to cope successfully with Australia’s harsh environment.

The wing design has provided the best compromise – a high cruise speed of 276 kt combined with excellent take-off and landing performance permitting operation at maximum gross weight from airstrips of approximately 1000 metres. Competitive designs have either had to choose between STOL performance (which is quite unnecessary in Australia for an aircraft in this category) or a high cruise speed and mediocre field performance.

The ATR 42’s high cruise speed will result in much shorter block times than with the Fokker Friendship. Even for sectors of 600 km, ATR 42 block times will stand in comparison with those presently being achieved with the F. 28 Fellowship, which means that some of the long thin’ regional routes could perhaps revert to turboprop operation with improved profitability.

The greater capacity of the ATR 42 compared with other new-generation transports results in less fuel burnt per seat km. This in turn contributes to giving the ATR 42 the lowest seat-km cost of any aircraft in this category.

The very large fuel capacity (4500 kg) is an advantage for Australian operations, firstly because regional routes here are longer than in many countries, secondly because Australian fuel reserve requirements are comparatively stringent, and thirdly because the ability to fly several sectors without refuelling will result in cost and time savings.

The ATR 42 will be certificated to cruise at up to 25,000 feet (limited by the requirement for individual passenger oxygen above that height and not by the pressurisation system which provides a maximum differential pressure of 6 psi). This high cruise altitude not only helps to avoid turbulence but also improves fuel economy on very long routes.

Cabin maximum width (2. 57 metres) and floor width (2. 26 metres) are larger than for any competitor, including Friendship. They contribute to the very high standard of comfort offered by the ATR 42, which also includes large galley, toilet and baggage/cargo facilities as standard fitment.

The main baggage/cargo compartment of the ATR 42 is located forward of the passenger cabin and immediately behind the flight compartment. This arrangement, so successfully used on the Friendship, eliminates trim problems and will permit random seating of passengers under any conditions. It also permits crew access to this compartment during flight.

Dual cooling packs of large capacity provide independent heating/cooling for the flight crew compartment and passenger compartment, a feature that should be appreciated in Australian climatic conditions.

The high-wing layout and widely spaced engines give more propeller/ground and propeller/fuselage clearance than is the case with competitive aircraft. The first should obviate propeller blade damage in operation from unsealed runways and the second should ensure a low level of noise in the cabin.

The regional airlines will no doubt examine the above points, as well as a number of other features when they start their search for new equipment.