Air Systems Flashcards
Which systems rely on bleed air for operation?
(i) Wing & Engine Anti Ice
(ii) Hydraulic & Water Pressurisation
(iii) Engine starting
(iv) Air conditioning/Pressurisation
(v) TAT Probe
Which compressor stages is bleed air obtained from?
5th & 9th stage compressors.
When will the DUAL BLEED light illuminate?
Whenever the APU bleed air valve and the engine bleed air valves are open at the same time.
When will a wing-body overheat condition exist?
When there is a bleed air duct leak.
Which pack does the flight deck receive conditioned air from?
The left pack.
What air combination does the passenger cabin receive? And where is it all combined prior to being distributed?
Excess air from the left pack, air from the right pack and air from the recirculation system. It is all combined in the mix manifold.
How many packs is the APU capable of supplying bleed air for?
(i) Two packs on the ground.
Or;
(ii) One pack in flight.
In what mode, and up to what altitude, can a single pack maintain pressurisation and temperature?
High flow mode, up to the maximum certified ceiling. (41,000ft).
In what aircraft configuration will the packs automatically switch to high air flow, in the event of a pack failure?
In flight, with flaps up.
What is the purpose of the ram air system?
To provide cooling air for the heat exchangers.
When are the ram air inlet doors in the full open position?
On the ground, or in slow flight with the flaps extended.
Does the cold and hot air mix upstream or downstream of the water separator?
Upstream.
What is temperature range for the zone controllers?
18 degrees to 30 degrees.
What is the purpose of the trim air system?
To fine tune individual zone temperatures; because the packs are trying to set a temperature for the zone that requires the most cooling.
What temperatures will each pack maintain if all temperature selectors are positioned OFF?
Left pack will maintain 24 degrees, and the right pack will maintain 18 degrees.
What is the purpose of the recirculation fans?
To reduce pack load and bleed air demand.
Where do the recirculation fans gather air from, and eventually send it to?
From the passenger cabin and electrical equipment bay, to eventually be sent to the mix manifold.
What is the maximum differential PSI that will be limited by the pressure relief valves?
9.1 PSI.
Up to what cabin altitude can the cabin pressure controller control?
8,000ft.
At what pressure differential from the selected FLT ALT will the pressurisation descent mode be activated?
0.25 PSI.
Which stage is primarily used for bleed air, and which is used to help maintain pressure in low power conditions?
The 5th stage is the main source, with the 9th stage used to maintain pressure.
What must thrust be limited to, when the DUAL BLEED light is illuminated?
Idle.
