Airframe system tutorial answer (Topic 3 ~ 14) 2010
8i) Power transfer units are used to pressurize a hydraulic system from another hydraulic system without the exchange of any fluids. The Power Transfer Unit usually consists of a hydraulic motor driving a hydraulic pump. 8ii) The Ram Air Turbines are usually used in emergencies when all hydraulic power is lost. Ram Air Turbines can be extended into the air stream outside the aircraft so that the air flowing through the turbine blade can drive a hydraulic pump to provide enough hydraulic power to actuate systems needed to get the aircraft safely on the ground. 8iii) An Auxiliary Power Unit is a compact, self-contained unit that provides electric power and compressed air to drive hydraulic pumps during periods of ground activity or in flight if needed. The Auxiliary Power Unit consists of a small gas turbine engine with engine controls. Its compressor bleed system is connected to the airplane’s pneumatic systems and provides pneumatic power for airplane functions.
Done by Lin Zhi Yong (0710125) (DARE/FT/3A/24)
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