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The first German jet engines built during the Second World War used a mechanical APU starting system designed by the German engineer Norbert Riedel.It consisted of a 10 horsepower (7.5 kW) two-stroke flat engine, which for the Junkers Jumo 004 design was hidden in the engine nose cone, essentially functioning as a pioneering example of an auxiliary power unit for starting a jet engine.
In some aircraft, the shut-off function is a different valve located after the fuel selector valve. Typically, after the selector valve—situated at a low point in the fuel run—there is a gascolator — a fuel filter that can be opened on the ground and drained of fuel impurities denser than petroleum, mainly water and sediment. Other ...
This bleed air is directed into a mechanism to start the engine turning and begin pulling in air. The starter is usually an air turbine type, similar to the cartridge starter, but uses the APU's bleed air instead of the burning gases of the propellant cartridge. Most cart starters can also use APU air to turn them.
Gas turbine aircraft engines such as turbojets, turboshafts and turbofans often use air/pneumatic starting, with the use of bleed air from built-in auxiliary power units (APUs) or external air compressors now seen as a common starting method. Often only one engine needs be started using the APU (or remote compressor).
Bleed air in aerospace engineering is compressed air taken from the compressor stage of a gas turbine, upstream of its fuel-burning sections.Automatic air supply and cabin pressure controller (ASCPC) valves bleed air from low or high stage engine compressor sections; low stage air is used during high power setting operation, and high stage air is used during descent and other low power setting ...
The quantity of bleed air flowing to the AC pack is regulated by the flow control valve (FCV). One FCV is installed for each PACK. A normally closed isolation valve prevents air from the left bleed system from reaching the right PACK (and vice versa), although this valve may be opened in the event of loss of one bleed system.
The first production model, the TFE731-2, began rolling off the assembly line in August, 1972, and was used on the Learjet 35/36 and Dassault Falcon 10, both of which entered production in 1973. The TFE731-3 was developed for use in the Lockheed JetStar re-engining program, and subsequent versions of it have been used on a number of aircraft ...
Compressed air is sent to the ATS turbine from the aircraft auxiliary power unit ( bleed air from the gas generator or from a free-turbine load compressor, eg PW901 APU), from an already-running engine (bleed air) on a multi-engined aircraft or, for early jet aircraft, from an air compressor mounted on ground support equipment.
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