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A diagram of the aft pressure bulkhead of the Boeing 747 used on Japan Air Lines Flight 123. Multiple instances of damage to the aft pressure bulkhead have occurred; while a few cases have led to serious failures leading to aircraft losses, others have proven to be survivable.
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 ...
Air bled from the engine fan is blown across the pre-cooler, located in the engine strut, and absorbs excess heat from the service bleed air. A fan air modulating valve (FAMV) varies the cooling airflow to control the final air temperature of the service bleed air. Notably, the Boeing 787 does not use bleed air to pressurize the cabin.
An interesting feature of all three German jet engine designs that saw production of any kind before May 1945: the German BMW 003, Junkers Jumo 004 and Heinkel HeS 011 axial-flow turbojet engine designs was the starter system, which consisted of a Riedel 10 hp (7.5 kW) flat twin two-stroke air-cooled engine hidden in the intake, and essentially ...
Low pressure (40–70 psi or 280–480 kPa), high volume air from the compressor section of the APU is bled off through a system of pipes to the engines where it is directed into the starting system. 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 ...
A 66,500 lbf (296 kN) thrust version (GEnx-2B67) will be used on the 747-8. Unlike the initial version for the 787, this version has a traditional bleed air system to power internal pneumatic and ventilation systems. It will also have a smaller overall diameter than the initial model to accommodate installation on the 747.
The part of the bleed air that is directed to the ECS is then expanded to bring it to cabin pressure, which cools it. A final, suitable temperature is then achieved by adding back heat from the hot compressed air via a heat exchanger and air cycle machine known as a PAC (Pressurization and Air Conditioning) system. In some larger airliners, hot ...
This system is not affected by any additive or fuel combination to replace 100LL for piston-powered aircraft. Single-engine light aircraft fuel tanks are usually in the wings, but some aircraft have a small "header tank" between the normal fuel tank and the engine, to facilitate reliable fuel flow to the engine.