Testing full power thrust of jet engines

The sound of jet engines in Dubai is set to get louder with the construction of the new Emirates engine test facility. Zoe Naylor visits the building designed to handle 150,000 pounds of thrust.

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By  Zoe Naylor Published  April 8, 2006

|~|116proj200.gif|~|The facility will comprise a structural steel preparation building (top) and a reinforced concrete testing facility (bottom) with 600mm thick walls.|~|Emirates is rapidly expanding its fleet and plans to more than double its fleet size by the year 2012. But like any airline, it must continually test its aircraft’s engines to make sure that they meet performance requirements. While the smaller engines are currently sent to a test facility in Abu Dhabi, the larger models need to be partially dismantled and flown to test centres in Hong Kong or Singapore. But this is about to change with the introduction of Emirates’ very own engine test facility, which is currently under construction on Academic City Road in the Lehbab area of Dubai. “There are two key uses of the facility,” explains Ben Othman Abdelkader, engineering power plant vice president, Emirates. “It is a test facility for engines that are being overhauled i.e. they undergo functional testing to make sure that they meet all the mechanical and performance requirements.” It is also used when any troubleshooting on an aircraft will take time. In such cases, the engine will be removed, and the work will continue on the test cell in order to avoid lengthy aircraft grounding. “Essentially the test facility is a large concrete enclosure where we will mount the engine as if it were mounted on the wing,” says Tony Anderson, programme manager at GE Transportation (Aircraft Engines). Operational tests can then be carried out on the engine to ensure its mechanical and performance integrity. The facility is also capable of testing the APUs (auxiliary power units). “Post overhaul, an engine must be tested in a test cell facility before it can be installed back on the aircraft,” says Abdelkader. He adds that the Emirates test centre will cater for the most powerful engines existing today, which have 115,000 pounds of thrust. “We don’t know at this time what the thrust will be in the future; but this test cell centre is capable of handling 150,000 pounds of thrust.” This will be the first test facility in the Middle East capable of handling this amount of thrust. “Currently, the maximum test capacity in the region caters for up to 80,000 pounds of thrust, and is in Abu Dhabi,” says Anderson. “This new facility will be one of a dozen in the world — and the only one in this region of its size. The test facility is made up of two main components: A u-shaped turbo fan concrete test cell (this is where the engines will be tested); and a steel structured preparation building. Burns & McDonnell from the US is responsible for the architecture and engineering on the project, as well as site supervision and project management, in collaboration with Sharafi-PHB as the local consultant. According to Edward Fayyad, general manager at Burns & McDonnell (Dubai office), the test cell has four elements: “Firstly there is an intake stack around 22m-high where the air comes in,” he explains. “Then there is the test chamber itself, where the engine will be hung for testing. This is about 37m long. Then there is the 26m-long augmenter section where the exhaust of the engine is sucked into a six-metre diameter augmenter tube. Finally there is the second leg of the u-shape that is the 26m-long exhaust stack,” he adds. The stacks and the test chamber have a cross section of 13m by 13m. The cell is constructed from heavy reinforced concrete (40 Newtons per mm2 compressive cube strength) with 600mm-thick walls, designed primarily for acoustic purposes. The testing equipment, as well as the aero-acoustical elements, are supplied by Aero-Systems Engineering. “The second section of the facility is the preparation building,” says Fayyad. This steel structure measures 88m long, 36m wide and 17m high, and is clad with insulated metal cladding. This building serves three main functions. Firstly, there is a preparation area itself: This is where the engines that have been taken off the aircraft and brought into the facility are then prepared for testing prior to entering the test cell chamber. In the preparation area, there are six universal workstations capable of preparing a number of engines, as not all will be the same type. In total, five engine models available on Emirates’ fleet can be prepared and tested in the facility: GE90-115, GP7200 and Rolls Royce’s Trent 500, 700 and 800 engines. “The six workstations and the test cell chamber are all interconnected via a 30-tonne monorail and bridge crane system. Using this system, the engines can be lifted off the truck when they arrive at the facility and positioned in any one of the workstations that are available for use,” says Fayyad. While only one engine can be tested at a time, six can be prepared simultaneously. A turntable on the 11m-high bridge crane means that it can orient the engines in whichever direction they need to go and take them to wherever is needed. “Once the engine is ready for testing, the monorail and crane system will be used to transfer the engine to the test cell,” says Fayyad. The second function of the preparation building is to house the APU test cell — a mini concrete chamber within the test cell that tests the APUs (Honeywell GCP 331-500B, 331-350C and 331-600A). These are the small engines that supply the air conditioning and electricity to the aircraft when the engines are not running. While nowhere close to the size of the main u-shaped test cell, it is still made from reinforced concrete with 300 mm-thick walls. The third function of the preparation building is offices, control rooms, and a prayer room — the support facilities. There is also a pump house building for all the fuel that needs to be pumped into the test cell during testing: “We will have two 80,000 litre double-walled steel underground fuel tanks — this is what the engines will run on,” says Fayyad. “For an extensive engine test (which will take approximately four hours), the fuel used will be around 30,000 litres,” says Abdelkader. The project poses a number of structural and environmental considerations. According to Anderson, there are stringent requirements for the inside of the test cell in order to meet FOD (foreign object damage) requirements: “We need to make sure that no loose item within the test cell chamber can break out or shake itself loose from the structure. The fasteners, for example, have to be lock-wired or welded, and the lights are all embedded inside the concrete itself,” he says. “On top of this there are the seismic requirements and the engine dynamic loads. In particular, we have to consider rotor seizure loads — if the engine is running, a bearing fails and it suddenly locks up, the result will be increased loading into the structure,” adds Anderson. One environmental consideration specific to this region that has been introduced into the project is an inlet stack cap. “If we have severe sand storms then we can shut operations down and close the inlet off to avoid sand ingestion into the inlet,” explains Abdelkader. And according to Abdelkader, this is the first installation in the world to have a horizontal sliding door covering the intake to protect it from sand. Noise emanating from the facility during testing is yet another consideration. To prevent unwanted noise pollution in the vicinity, a 500m radius from the centre of the test cell has been designated as a no-build area. “The facility is designed to maintain a 70db noise level at 75m distance from the noise source. At the 500m perimeter, the noise is down to levels that are in accordance with Dubai Municipality standards,” says Fayyad. Construction of the facility started in June 2005. The main general contractor for construction is Group Five Construction (Dubai branch). Overall, the project construction is now around 40% complete. “The u-shaped test cell and the stacks for intake and exhaust are mostly finished,” says Fayyad. “The augmenter chamber is also finished and now the walls of the test cell chamber itself are being built,” he adds. Approximately 5000m3 of concrete is being used to create the test cell, which is being constructed in 4m-high lifts. Around 750 tonnes of reinforcement steel will also be used. Around 520 tonnes of structural steel was used on the preparation building, most of which is erected. And work has now moved to the roof cladding. The overall completion date of the project is scheduled for January 2007.||**||

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