FLUG REVUE November 2004: Airbus A380 prepared for first flight

A380 PREPARED FOR MAIDEN FLIGHT

By Sebastian Steinke

It is early in September in the Jean-Luc Lagardère final assembly plant at the Airbus site in Toulouse. Groups of technicians who seem like miniature people next to a giant Gulliver stand next to the first flying A380 prototype, serial number MSN 001, and breathe life into the biggest passenger aircraft in the world. The hydraulic reservoirs and fluid pressure lines of the double-deck Airbus flagship are filled with oil for the first time and raised to the operating pressure of 5,000psi (345 bar). The new hydraulic system works with a higher pressure than previous Airbus types, on which the operating pressure was 3,000psi, as this enables smaller lines to be used, thus saving weight. The future Boeing 7E7 will also use a pressure of 5.000psi.

A380 assembly

Before being filled with oil, the A380 line system had already at the end of August been filled with pressurised air and subjected to leakage testing, as well as being tested for the formation of cracks under pressure and for the absence of obstructions. The next batch of tests is now directed at the electrical hydraulic monitoring instruments in the cockpit and the warning displays situated there. After this, the electro-hydraulically activated control surfaces, spoilers and landing gear activation will be operated for the first time. In a series of five phases, the hydraulic system, which has already worked smoothly on the true-to-size “Iron Bird” system simulator in Toulouse, is being prepared for the maiden flight. Another innovation on the A380 is the fact that for the first time at Airbus the hydraulic pumps and fluid reservoirs are located in the engine pylons, rather than behind the wing root fairing.

On 6 September, MSN 001's main fuselage landing gear was retracted and extended for the first time on the real aircraft. This was preceded by the successful completion of test runs on the landing gear simulator in Filton. The A380-800 has two main landing gears on both the wings (each consisting of four wheels, non-steerable) and under the fuselage (each having six steerable wheels), plus the nose gear (two wheels, steerable). On later versions with greater take-off weight, an extra, central landing gear could be fitted. For the present landing gear test runs, known as “Gear Swing”, the prototype has been jacked up in its completion position. During these tests, engineers also adjust the closed landing-gear doors. Soon the brakes and steering, along with the associated electrical and hydraulic systems, will be actuated.

Compared with previous Airbus types, the retracted landing gear of the A380 will be locked in position electrically rather than hydraulically. At the other end of the 500m long, 250m high hangar, the second prototype MSN 002 is already standing on its own feet, namely on the Near Zero Growth (NZG) safety tyres developed for the Concorde. It was on final assembly station 41/40 that test fuselage MSN 5000 and the first prototype, MSN 001, first saw the light of day.

As we reported briefly in the last edition of FLUG REVUE, successful completion of the power-up carried out on 30 July, in which MSN-001's aircraft electrical system was connected to the power supply for the first time, was necessary before the present hydraulic tests could start. Since then, the four generators, the auxiliary power unit in the tail and several hundred kilometres of cables, the majority of them made of aluminium for weight reasons, have been tested to ensure they are functioning correctly. These tests in turn were preceded by laboratory tests and measurements on test rigs.

After all the elements had been individually analysed, entire functional systems were powered up, and this is now being repeated on the real aircraft. The procedure includes connection of the new generators with variable frequency to the primary and secondary power circuits, all of which supply end consumers. Even if the most serious sequence of system failures were to occur, the A380 could still be flown with only one hydraulic system or with only one electrical system. As soon as the power and hydraulics on board MSN 001 have been completely tested, the last critical stage before the maiden flight will be to mount the engines. As is well-known, the first Trent is already flying on an A340 test aircraft in Toulouse.

While the main components are being powered up and measured out, further equipment is being installed behind in the cabin, although in this case it is not with full passenger furnishings but with ballast tanks and test equipment. KID-Systeme of Buxtehude delivered the first Cabin Intercommunication Data System (CIDS) on 9 September. Its nondescript black box, approximately four times as big as a car radio, contains the computer that controls all the cabin communications and in-flight entertainment. From a central, touch-sensitive monitor, the senior flight attendant can control and monitor onboard telephone, passenger announcements, the LED cabin lighting with dozens of different light settings depending on the time of day (“mood lights”) , the cabin temperature, plus music, videos and computer games for passengers on both floors. On top of this are controls for the doors and escape chutes, the water supply for the toilets and kitchens and monitoring of the waste water installation. The CIDS is already installed as standard in the A320 family. A lot of importance was placed on later expandability via digital interfaces, to cater for any additional features that the airlines might wish to offer.

Back to the first flying prototype MSN 001. Strictly speaking, its designation within Airbus is A380-841. The number 8 stands for basic version -800, the number 4 for engine manufacturer Rolls-Royce and the number 1 for the first variant of the Trent engines on this aircraft type, the Trent 970. By contrast, later aircraft powered by the GP-7270 engine from Engine Alliance, manufacturer code 6, will be known as A380-861. Airbus has had the codes F-WWOW and F-WXXL reserved as the tail codes for the first two flying prototypes. Later production aircraft, which carry a price tag of up to $270 million, will be identified up to delivery by the French temporary code F-W plus a code from a continuous series – WSA (MSN 003), WSB (MSN 005), WSC (MSN 006) etc. – until customers register their A380's in their home countries. The only known exception is Virgin, which is hoping to get G-VXXL as the final tail code for its first A380 (MSN 010).

Altogether, the A380 certification programme, which consists of three phases, will require four aircraft. In the first two months following the maiden flight, the focus of attention will be on ascertaining the A380's basic flight characteristics. This first phase is known among the engineers as “initial exploration of aero configuration” and will examine the A380's elementary flying and handling characteristics. The data collected will be evaluated both during the flight and afterwards on the ground.

This will be followed by a six month period, in which the aircraft development will finally be frozen, once all the systems have been optimised. With the aid of the data obtained during Phase 1, it will be possible to fine-tune the third-generation flight control system, which compensates for turbulence, the autopilot and the primary systems. This will then be followed by the certification phase, during which the programme items prescribed by representatives of the aviation authorities are demonstrated. Environmental data, fuel consumption figures and the detailed configuration of the passenger cabin will then be the focus of attention.

During the preparations for flight testing, the first, non-flying test fuselage A380 “ES” (Essais Statiques), serial number MSN 5000, will also play an important role in the stress tests. MSN 5000 does not have any hydraulics or avionics equipment. Its two-year test life will begin in November. It is already parked in the special dock of its test hangar, next to the A380 final assembly line with the two prototypes. In the first, nine-week phase, the aircraft structure, together with leading-edge slats and landing flaps, will undergo structural testing both under normal conditions and under the most demanding conditions likely to be encountered. The results will flow directly into the performance calculations for the maiden flight of MSN 001. After that, things will toughen up considerably for MSN 5000: for a whole year the fuselage, anchored to the floor of the test hangar by an array of steel cables, will be subjected to extreme loads, including overloading in every possible simulated flight phase and attitude. Once again, this series of tests will produce important evidence for certification purposes. Once the A380 has been certificated at the beginning of 2006, as expected, the crunch will finally come: MSN 5000 will be deliberately stressed to breaking strength. This will enable the engineers to see whether cracks and fractures form and develop as predicted. The results can be used to test the computational models that they have been using, which will be needed for future aircraft developments.

From page 20 of FLUG REVUE 11/2004

Last updated 13 October 2004

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