Airbus is working furiously to clear the series of hurdles that must be negotiated before the A380 can make its first flight from Toulouse early next year
Airbus is confident the A380 will fly on schedule early in the new year, but not before it has completed a series of detailed tests and evaluations to ensure the aircraft is ready to leave the ground. As engineers work to complete the extensive pre-flight structural- and ground-test programme - now under way using the first two A380s and the static-test specimen - the entire flight-test team is preparing a full dress rehearsal of the A380's maiden sortie as a "virtual first flight" using the simulator linked to the iron bird test rig.
In one of the giant hangars at the Jean-Luc Lagardère final assembly site in Toulouse, the first three A380s (manufacturer's serial number (MSN) 001 - the first to fly - 002 and 004) are undergoing systems installation and testing at assembly Station 30. In a building adjacent, the static-test article ("ES" - the first A380 airframe to be completed) has just begun two years of structural testing, but has some critical limit-load capability demonstrations to complete before MSN001 will be allowed to take flight.
Assembly of the fourth flight-test A380 (MSN007) began in Toulouse on 18 November, following a hiatus on the line to allow the assembly team to decamp to Dresden, where they have completed structural build of the fatigue-test airframe. Testing on the fatigue airframe will not begin until September 2005, as it is not part of the pre-flight testing, but Airbus aims to have accumulated 5,000h of testing by the time of A380 certification in the first quarter of 2006.
By the time MSN001 has been painted for its formal "reveal ceremony" in Toulouse on 18 January, the aircraft will have undergone six months of test and completion work in preparation for its first flight. This is likely to take place around a month after the unveiling.
Assembly of the flight-test aircraft is roughly similar to that of the series production aircraft, although the process has been extended considerably as obviously complex pre-flight systems installation and testing is required.
Following structural completion at Station 40, each A380 is backed out of the hangar on its main wheels and moved to Station 30 in another part of the plant where its engines, auxiliary power unit, air conditioning packs and ram air turbine are installed, and system tests are carried out.
Development tests
Once series production is well under way, this process will take three weeks, but for the flight-test aircraft, in particular MSN001, the process will be a much longer, explains Mark Cousin, head of engineering support to A380 final assembly line and flight test: "As well as the serial tests, which will be performed on every aircraft, we will also undertake development-aircraft-specific tests to prove the correct operation of systems as designed." In all, MSN001 is spending nine to 10 weeks at Station 30, he adds.
Cousin gives some examples of the main development tests planned for A380 MSN001. These include function tests for:
* flight controls (normal and back-up) ;
* trimming horizontal stabiliser;
* braking and steering;
* bleed air system;
* slats and flaps;
* door operation and position sensing.
There are also trials of the landing gear, including a fit-check of the wheel and tyre clearances in their bays, and gear extension and retraction. "On MSN001 the extend/retract test was initially carried out using an external hydraulic supply, and tests with onboard supply are due to begin on 22 November," says Cousin.
Examples of the equipment to be checked during the production tests, which every A380 will undertake at Station 30, are:
* electrical generation system;
* fuel tank and pipe leakage check using helium gas;
* lights;
* APU fire detection and fire extinguishing systems;
* cargo and avionics-bay smoke detection;
* engine fire detection and fire extinguishing system;
* wing and engine de-icing system.
MSN001 now has two of its four Rolls-Royce Trent 900 engines installed, and the other two are ready for installation in the podding facility. The Pratt & Whitney Canada PW980 APU will be installed at the end of the Station 30 process.
The Trent 900 was certificated on schedule last month, having taken to the air on Airbus's A340-300 flight testbed aircraft in May. Executive vice-president A380 programme, Charles Champion says the engine has shown "satisfactory behaviour after almost 40 flight hours". He adds that Airbus will use the testbed to carry out icing trials in January, using the natural icing available at that time of year to derisk the icing aspects of the A380 flight-tests.
During the installation and testing process at Station 30, MSN001 (and later MSN004) is being equipped with a mini-cabin in a small section of the upper fuselage. This comprises interior furnishings (sidewalls and ceiling panels), galley, lavatory and overhead stowage bins.
Cousin says that most of the flight-test instrumentation has been installed at section level before delivery to the final assembly line. "The system is then connected and measurements validated on the line," he says.
MSN001 is equipped to record 6,000 measurements, with for example a sophisticated in-flight loads monitoring system using strain gauges in critical areas of the structure, pressure sensors in the hydraulic systems, video cameras for monitoring landing gear operation, and laser anemometry for accurate measurement of aircraft speed. There are two positions for flight- test engineers on the main deck and one on the upper deck. In addition, for most tests, telemetry will be used to transmit data in real time to a team of ground-based engineers monitoring the tests.
Cousin says that, once the Station 30 work is competed, the aircraft will be moved outside to Station 18 for its fuel and cabin pressurisation testing. "This is due to start next month," he says.
The Station 18 process will take around four to six weeks, says Cousin, compared with three weeks once series production is fully established. "We will calibrate the fuel tanks to determine gauged versus actual quantities, as well as checking expansion volumes, refuel rate, and the unpumpable, undrainable fuel quantities to establish the maximum usable quantity," he says. "We'll also carry out surge pressure tests, and carry out a new test - centre of gravity targeting."
Cousin adds that the cabin pressurisation tests will comprise air leak and overpressure tests - the latter to a 1.33 times the design pressure - as well as a check of the outflow valve/safety valve operation. During the Station 18 phase, MSN001 will be moved into the hangar for painting (only MSN001 and 004 will be painted in Toulouse).
Once the Station 18 process is completed, the test aircraft will depart the production aircraft process and move to two unique Stations - 22 and 17. When production is fully established, A380s will move from Station 18 to 15 for preparation for ferrying to Finkenwerder, where they will be outfitted and painted.
At Station 22, MSN001 will undergo systems and equipment upgrades, and testing in preparation for the first flight. "We will swap out any non-flight-rated items that were installed during the build process, as well as implement upgrades and changes that have come out of the ground test phase, as well as replace any defective equipment," says Cousin. "This should be a relatively short phase, but it will depend on the amount of equipment deemed necessary for replacement."
Pre-flight checks
While MSN001 is undergoing its mammoth ground-test schedule, MSN002 will be tasked with ground vibration testing to clear the A380 for flight. "Before the first flight, we need to measure the structural modes of the real aircraft structure, ie, the frequency and damping, and validate aircraft models used for flutter clearance," says Cousin.
The completion of MSN002 is running behind that of MSN001, with the aircraft having undergone a partial power-on at the end of October involving cockpit and electrical generation systems. The full power-on is scheduled next month. The ground vibration testing programme is due to start in December and will last about three weeks, says Cousin, with the work having been contracted out to the French aerospace research centre Onera and German aerospace centre DLR. "With the aircraft on jacks, small excitation forces will be applied to the airframe. Measurements of the structural response for a range of excitation frequencies will be made using accelerometers," explains Cousin.
The static-test airframe "ES" also has a part to play in the build-up to flight test, by providing data to support first-flight clearance requirements. ES was moved into a dedicated 10,000m2 (107,600ft2) hangar in June where the static test equipment has been built up around it. It is now surrounded by 306 jacks and 8,000 gauges, with the entire rig weighing around 1,000t.
"Static testing started in November, and for first flight clearance we have several tests to complete," says Jan Stueben, director of structure on the A380 programme.
Stueben says that the pre-flight tests comprise:
* 1g bending test to check gaps and interference of flaps and slats;
* flight-test instrumentation calibration;
* maximum wing bending at limit load;
* functioning of flight controls (ailerons and spoilers) the under limit-load deflected shape of the wing structure.
The static-test airframe will be used to calibrate MSN001's in-flight loads monitoring system, with a final cross-check on MSN001 for critical measurements.
In addition to ES, Airbus has constructed a complete aft fuselage and tail test rig (dubbed the rear-end test) to provide data in support of composite-structure certification. This will also undertake a series of tests in December to clear the aircraft for first flight.
Final assembly
The last pre-flight station for MSN001 is 17, where it will undergo final checks and preparation shortly before its maiden voyage. "MSN001 should spend two to three weeks at Station 17, and then we'll be ready to fly," says Cousin. "We'll check the radios, thrust reversers, ram air turbine deployment, oxygen system and then hand the aircraft over to the flight-test organisation." After final engine and APU runs, MSN001 will carry out a taxi test and low-speed accelerate/stop check, followed by a high-speed run to take-off speed and a stop. "The first flight should be one or two days after this," says Cousin.
MSN001 will launch the four-aircraft, 2,000h flight-test programme and should be joined by the second dedicated flight-test aircraft, MSN004, by the second quarter of next year.
MSN002 is destined to serve as one of the two Trent 900-powered route-proving aircraft (the other being MSN007), so once its ground vibration testing phase is completed it will be prepared for its ferry flight to Finkenwerder for cabin furnishing and painting. It is due to join the test programme in the third quarter of next year, when it will undergo the so-called early long-range flights with Airbus staff aboard.
After assembly of the first four test aircraft, there will be a gap in production before construction of the first customer aircraft (MSN003) begins. This aircraft will be delivered to launch operator Singapore Airlines following certification of the Trent 900-powered A380, which is scheduled at the end of the first quarter of 2006.
The first A380 powered by the General Electric/Pratt & Whitney Engine Alliance GP7200 will be the seventh aircraft built - MSN009 - which is due to fly late next year. This will be one of two A380s dedicated the GP7200 test programme and will be used for performance evaluation and propulsion system certification.
MSN007, which will be used for route-proving towards the end of the Trent 900-powered/A380 certification programme, will be re-engined to carry out a similar task for the GP7200 test effort, ahead of planned service entry of this version of the A380 with Emirates in October 2006.
MAX KINGSLEY-JONES / TOULOUSE
Source: Flight International
