The 737 NG APU is recognisable by the “eductor” cooling air inlet above the exhaust. This and a redesigned silencer make the NG APU 12dB quieter than the Classics. The eductor works by using the high speed flow of the APU exhaust which forms a low pressure area.

The APU is usually located at the rear of the aircraft, in the tail, so the intake is generally somewhere on the side of this location. Aircraft place the inlet in different places though, and some even put the APU somewhere different. For some examples: 737 intake, the small NACA inlet at the bottom

Oct 7, 2016 · During an airplane operation, the air inlet scoop supplies forced outside air through the empty space between the APU insulation panels and the bulkhead for ventilation and for the removal of flammable or unwanted fluids.

APU configuration, function and style of operation are all examined here, together with maintenance requirements and management. The APU is a gas turbine coupled with an air pressure generator and a gearbox.

When commanded by the pilot, the APU can start fully automatically with just the flick of a switch and can operate up to the maximum certified altitude of each aircraft (in the case of the Boeing 737-8, said altitude is 41,000 feet).

Apr 20, 2021 · A detailed description and history of the various APUs on all generations of the Boeing 737.Contents0:00 Intro2:47 Components5:16 Types of APU13:13 Captions2...

Nov 4, 2010 · As said, it's to improve high altitude starting by directing airflow into the intake. Don't forget, most other modern types have retractable scoop intakes which force air into the APU at high altitude, which the 73 lacks.

APU max air demand: 90 lbs/min on the ground (restricted by APU bleed valve). 80 lbs/min in the air. APU bleed valve is an electro-pneumatically operated solenoid valve. When electrical load and bleed air extraction combine to raise the EGT above acceptable levels, the bleed air valve will modulate towards the closed position.

Welcome to the 737 Tutorial Series. This video will cover the normal operation of the Auxiliary Power Unit (APU), as well as the operation and system logic ...

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