The construction and equipment installation of three ultra-long-range A321XLR test aircraft is undergoing final finishing touches at the final assembly line in Hamburg, Germany. Among them, the A321XLR with production serial number (MSN) 11000 has been successfully handed over to the flight test team. At the same time, Airbus sites are fully advancing ground test activities in preparation for the upcoming flight tests and certification.

One of them is the "Virtual First Flight" (VFF) campaign, the overarching goal of which is to clear all hurdles regarding the aircraft's new systems, flight control laws and crew so that flight tests can begin. The development of the A321XLR revolves around a dedicated R&D simulator and a co-located collaborative avionics test laboratory in Toulouse.

The virtual flight test differs from the full-motion flight simulator, which is moved by hydraulic jacks, in that the R&D simulator is fixed to the ground. In addition to being equipped with a real pilot control and display system, there is a dedicated workstation behind it, with the same displays and user interface that a flight test engineer (FTE) uses to monitor flight and adjust test parameters in a real aircraft. Adjacent to the entrance to the R&D simulator is a large virtual flight test laboratory that includes many of the actual avionics modules that are currently installed in the avionics bays of the three A321XLR test aircraft. In addition, the modules can be connected directly to the simulator for virtual flight and evaluation by Airbus test pilots, with simultaneous monitoring by their FTE colleagues.

Connecting the avionics in the lab directly to the simulator enables engineering test pilots to validate the A321XLR's improved flight control system laws under specific conditions (such as during flat or high-speed flight) and to respond to the normal flight conditions of the aircraft. The handling of external disturbances is evaluated and fine-tuned.

Vincent Claudel, Head of the Laboratory and Flight Test Integrated Product Team, said: “The virtual flight test campaign, which began in March this year, will conclude with a virtual maiden flight (VFF) 'dress rehearsal' or test run. During this exercise, all flight crew members Personnel, including test pilots, flight test engineers and flight test engineers who have been confirmed for the maiden flight, will rehearse in the simulator all the procedures that will then be performed on the real aircraft."

Vincent added: “The rehearsal process during the VFF commissioning included electrical and engine power up, taxi out, takeoff, climb, opening of the flight field, all the way to landing, taxi back, power down, etc. In fact, everything was the same as the actual flight. The process is exactly the same, and the sequence is exactly the same.”

Flight Control System Functional Integration Testing To validate the flight control computer for subsequent integration with the main simulator, engineering experts first complete the avionics module in a nearby laboratory using the Control and Guidance Integration Workbench (CGIB). testing and fine-tuning.

"Before connecting the avionics module to the simulator, we need to perform integrated operational testing to verify it at the system level to ensure that the flight control laws it controls are performing well," Vincent noted.

"Iron Bird" and the new eRudder The simulator can also be directly connected to and controlled by the aircraft's physical hardware, such as the hydraulically actuated control surfaces on the test stand. In an all-new model program like the A350, the testbed is known as the "Iron Bird." However, since the A321XLR is derived from the A321neo, it only needs to provide a physical test bed equivalent to the tail of the aircraft (especially the vertical tail). This is to facilitate ground testing of the new electronic rudder (eRudder) architecture, which is gradually being rolled out to other members of the A320 family of aircraft.

Ground system integration and testing

Vincent said: “Most of the tests carried out in preparation for the A321XLR’s maiden flight, such as flight control laws and autopilot tests, were performed by Toulouse engineers and flight testers in simulators and avionics benches. However, other Testing activities have been carried out successively at various Airbus sites for over a year to bring other systems relevant to specific ATA specification chapters into compliance." To this end, multinational companies in Toulouse, France, Hamburg and Bremen, Germany and Filton, UK The R&D team collaborated on A321XLR testing and system integration activities.

"There are two large test rigs in Filton, UK, which we call 'Landing Gear Zero', to validate the newly upgraded landing gear, tyres and brakes of the A321XLR (ATA Chapter 32). Phil Dayton also has a 'fuel integration test bench' for testing the A321XLR's new fuel and inerting system (ATA Chapter 28), in particular the validation of the new optimised rear center tank (RCT)."

“Meanwhile, we have a high-lift system bench in Bremen, Germany, for validating the new inboard single-slotted flap configuration unique to the A321XLR. In Hamburg, we have an air-conditioning system bench (ATA Chapter 21), as well as “drinking” Water and Sewage” System Workbench (ATA Chapter 38). In addition, Hamburg is equipped with an environmental chamber to optimize cabin and cockpit comfort during long-haul flights at high cruising altitudes.”

Hamburg uses 'environmental chamber' to recreate external atmospheric conditions on long-haul flights

"Even after the maiden flight, ground laboratory testing at these sites, as well as simulator testing in Toulouse, will continue, while supporting flight testing activities and certification subjects and other activities throughout the year," said Vincent.

Reviewing Editor: Peng Jing

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