The British Airways Flight Training (BAFT) centre at Heathrow offers CAA and JAA approved training and familiarisation courses on a wide range of aircraft, including Boeing 737, 757, 767, 747, 777 and Airbus A320. The facility is the largest civil aviation training centre in the UK, and trains BA's own flight crews and those of other major passenger airlines and cargo carriers.
The site on which BAFT is located is managed by British Airways Properties, which has set up an Energy Saving Working Group tasked with energy saving initiatives throughout Heathrow, encompassing everything from offices to aircraft hangers. As British Airways Property Manager, Alan Glenister, explains, the flight simulators make BAFT one of the heavier users of power, so investment in energy saving initiatives in this area can give large reductions in emissions to improve the overall carbon footprint. Availability, however, is a key requirement, as Brian Woodgate, senior simulator development engineer, points out:
“Our 14 full flight and four fixed base simulators are in constant demand, with training courses being fitted around the operational rotas of flight and cabin crews. It is therefore crucial that each simulator is available around the clock and functions efficiently and reliably. We are currently undertaking a scheduled programme of upgrades that are designed to improve the overall energy efficiency of the training centre by reducing energy consumption and costs.”
Each simulator is in a self-contained cell, which incorporates specialised computer and hydraulics rooms for driving the system, plus dedicated environmental control systems. These are designed to maintain the ambient temperature within set limits, providing cooling for the complete cell area, including the computer and hydraulics plant, and the enclosed flight deck within the simulator.
Senior engineering technician, Dennis Doody, emphasises that the performance of each environmental control system is critical, both for the comfort of trainers and crews and to ensure that all equipment operates efficiently. For example, each simulator uses three image projectors to create the high definition 3D images seen through the cockpit windows. The image is projected onto a curved mirror, mounted within the body of the simulator, with a thin Mylar outer layer that is held in place by vacuum. Changes in ambient temperature can affect the operation of the vacuum pump, which, in turn, can adversely affect the magnification, clarity and realism of the projected image.
Previously, the air handling units in each simulator cell used an arrangement of motor-driven fans that were continuously driven at maximum speed, regardless of demand. As Mr Doody points out, this was extremely inefficient, not just in terms of energy consumption, but also wear and tear on components such as motor bearings, drive shafts and belts. Moreover, running the fans at maximum speed made it difficult to achieve precise control of the environmental conditions in each cell, and the air handling systems were accounting for a significant proportion of all energy used in each cell.
The air handling systems upgrade was subsequently carried out by British Airways with the help of its contractors and suppliers, the drives specialist, Parker SSD, building services control system specialist, Trend and Emcor, who carried out the engineering work.
Each of the air handling systems uses a large fan, typically driven by a single 11kW motor to draw air into the air ducts, from where it is passed through a pre-heater and then either to a cooling or heating battery, depending on ambient temperatures. An extraction fan of up to 16kW maintains atmospheric pressure in the cell. A series of dampers is used to control the air flow and draw in outside air if the external temperature is lower, in order to benefit from a free cooling effect.
In this upgrade, the original fan motors are retained and are now controlled by Parker 650V ac variable speed drives, interconnected via a Trend building management unit. This enables the fans to be driven slowly or at idling speeds for most of the year, or at maximum output during especially warm weather. The drives are designed to be easy to configure, even in complex open-loop applications, and to provide a wide range of power outputs and options.
Mr Doody has experience of drives from various suppliers and says that the Parker units are “among the best available”. They are simple and straightforward to use, in his opinion, and offer a lot of functionality. The modular design, moreover, makes it easy to make changes to the control panels, should these be needed. Just as importantly, given BAFT’s requirement to keep the simulators available 24x7, is the fact that Parker manufactures in the UK and is able to offer local technical support and immediate access to replacement parts in an emergency. The modified air handling systems with the new drives have now been fitted to two of the simulator cells, and these are achieving significant energy savings, as Brian Woodgate explains.
“The combined Parker and Trend system is enabling us to reduce our energy consumption in each cell by a massive 95%, while at the same time cutting costs in other areas. For example, we previously needed to change filter elements every three months; now we only need to fit new elements once a year, while wear on moving parts such as bearings has been considerably reduced; our motors thus last longer with less routine maintenance. Also, as the air handling units now run for most of the time at low speeds the overall noise level in each simulator cell has decreased, improving working conditions. Finally, and most importantly, these upgrades are extremely cost effective, giving us a payback period of under two years, and the ability immediately to reduce our carbon footprint.”