Aircraft Bleed Air Control Units

It allows the bleed air isolation valve to open, permitting a crossflow of bleed air between the left and right systems.

Compressor section of the left and right engines, Auxiliary Power Unit (APU) bleed air, external air cart

By Bleed Air Controllers (BACs) that monitor the air supply via sensors within the ductwork

<p>Precooler heat exchanger; 5th (mid-stage) or 8th (high stage) of the compressor sections of the engines</p> Signup and view all the answers

<p>By cycling electrical power to the BAC off and on</p> Signup and view all the answers

<p>When selected to ON, essential 28V DC bus power is provided to the associated system, and the associated Bleed Air Controller performs a BIT check and establishes operational parameters.</p> Signup and view all the answers

<p>Air conditioning and engine starting on the ground</p> Signup and view all the answers

<p>By selecting the ISOLATION switch to 'ON'</p> Signup and view all the answers

<p>Air conditioning and pressurization, Pressurization safety valve, Wing anti-ice, Engine starting, Aircraft water system, Total Air Temperature (TAT) probe airflow (ground only)</p> Signup and view all the answers

<p>5th (mid-stage) or the higher temperature 8th (high stage) of the compressor sections of the engines</p> Signup and view all the answers

<p>By selective switching between compressor stages for a source of supply air and by passing the supply air through a precooler heat exchanger that uses ambient air drawn into the engine at the fan intake stage of the compressor</p> Signup and view all the answers

<p>To control the amount of fan air through the precooler to limit the temperature of the air in the bleed air manifold.</p> Signup and view all the answers

<p>The left BAC is co-powered by 28V DC from the left Essential DC bus through circuit breakers, and the right BAC is co-powered by 28V DC from the right Essential DC bus through circuit breakers. The BACs can be reset by cycling electrical power to the BAC off and on.</p> Signup and view all the answers

<p>The high-stage provides temperature augmentation by mixing the high-stage air with mid-stage air and changes the temperature control set point at the precooler inlet to 630°F (332°C).</p> Signup and view all the answers

<p>The purpose of the APU bleed air is to be inhibited when sufficient engine bleed air is available.</p> Signup and view all the answers

<p>When selected to OFF, the associated manifold pressure regulator valve closes and power is removed from the associated system.</p> Signup and view all the answers

<p>The APU may be used for starter-assisted main engine starts at and below 30,000 ft if required.</p> Signup and view all the answers

<p>The APU cannot be used to supply pressurization airflow in flight.</p> Signup and view all the answers