Airframe Systems

Topics: Cabin pressurization, Gas compressor, Compressed air Pages: 5 (1868 words) Published: October 15, 2012
P1 – State three purposes of pneumatic supply system for a typical piston engine powered light aircraft, and give the functions of the piston engine air compressor and receiver, within the system. An aircraft powered by a piston engine usually tends to have a pneumatic air supply system. This allows the function of different systems on the aircraft that are essential to the flight of the aircraft. In a newer system the supply system will provide a vacuum of air for the gyro’s, so that the de icing boots on the leading edge of the wings can inflate, for example, the boots on the jet stream wings inflate. The vacuum sometimes provides for some of the flight controls. An example of these flight controls would be the auto pilot system. The piston powered aircraft tend to consist of a receiver and a compressor. The compressor collects the air from the intake of the engine, creating a high volume of compressed air and storing it, acting like a storage tank. The receiver is there to make sure that the volume of air is consistent and smooth, else parts may move with too much force and damage themselves. In modern day aircraft, the only pneumatic system used is there to drive the autopilot system and the gyros. P2 – describe how air is supplied to the cabin pressurization system pre-cooler, for a typical passenger aircraft that’s powered by gas turbine engines, include in your answer where the air supply is taken off the engine The cabin pressurization system is designed to keep the pressurization of the inside of the aircraft to a higher level than outside the aircraft, this is done by taking air from the ram stage of the gas turbine. This air is then supplied to the heat exchanger at minimum pressure. When the aircraft is in flight, the air is bled from the low pressure stage of the compressor, this supplies air to the aircrafts pneumatic systems. But when the aircraft is on the ground at a standstill, there is no pressurization in the gas turbine. The high pressure stage of the compressor is manually operated on the ground when the engine is idling. A regulating valve is used to regulate the pressure of the bleed air when it has been taken from the pressurization stage of the engine. the air is then passed through a heat exchanger and dehumidified. The hot air is cooled and the heat exchanger is fed by cool air directly from the early compression stage of the engine.

P3-with aid of diagrams describe the purpose of the aircraft cabin pressurisation systems, for a typical pressurized airframe. In your answer state the function of the following system features : I. Ram air ii.bleed air iii.the air cycle unit and the humidifier(water extractor) On passenger aircraft, a control system is there to monitor and control the temperatures of the cabin area. The cabin conditioning and the pressurization system would be -56°c and would be impossible for passengers to survive the lack of pressure and breathe, as the aircraft flies at a very high altitude. The control system is there to control the cabins temperature and maintain the cabins pressure. The control system has 2 related systems, one of them is for the temperature control and the other is for pressurization. Both of these use the engine bleed air. The hot pressurized air passes through the heat exchanger. This cools down the air as it passes through, reducing the air to the desired temperature. When the hot pressurized air enters the air conditioning pack, it passes through a valve that controls the air pressure before passing through the heat exchanger. The heat exchanger is there to dissipate the heat as the air passes through them, they are positioned inside the ram air ducts, sometime on the underbelly of the aircraft. The ACU’s role is to cool hot bleed air. The system works similar to a refrigerator except there is no condensation or evaporation of a refrigerant involved. The unit consists of a small air expansion turbine and a compressor, connected by shaft. The...
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