Air Conditioning and Pressurisation Flashcards
(30 cards)
How may air conditioning packs are installed?
2
Is a single pack enough to satisfy the requirements?
Yes
Which pack supplies which area?
Pack 1 flight deck into common duct
Pack 2 cabin
What conditions must be met or a pack valve to open?
at least 10PSI in bleed system
no auto shut off and no overheat
When will auto shutoff of both packs occur?
- on ground during engine starting or both thrust reversers are unlocked
- if engine failure is detected during takeoff or in flight at altitudes below 13500ft and a thrust lever setting above MIN takeoff is selected
How is pack operation restored after an auto shutdown due engine failure?
by operating AIRCOND AUTO SHUT pb or by selecting a lower thrust setting. Will be automatically restored when climbing above 13500ft.
How are normal and economy flows selected?
manually via ECON pb. ECON is achieved when both pack valves are open and the auto controlled cabin temp is within a preset range from the selected temp.
economy is automatic during:
- takeoff, normal is restored 1 min after takeoff
- upon TOGA activation, restored after 1 minute
- as long as max TO thrust is selected
What is augmented flow?
operative when one pack is manually switched OFF
If you are in economy mode and a pack fails, what happens?
Normal , then when off, goes to augmented mode.
How do you select a cabin or flight deck temperature?
via the temperature selectors.
Where is air temperature displayed?
on air con panel
How is the flight deck and cabin air distributed?
flight deck: via air outlets on side walls, ceiling, pedestal and floor
cabin: cabin wall,
How many re-circulation fans are there, what do they do and how are they controlled?
4 fans. mounted in cabin ceiling to recirculate air, controlled by RECIRC FANs pb.
How and when would you introduce RAM air into the aircraft?
when unpressurized
What happens to the air con system if an engine failure occurs above 13500ft and below?
assuming thrust lever above MIN TO is selected:
If above, econ mode.
If below, both packs auto shut off.
Is there any time the automatic switch to economy flow will not work?
When both in manual mode, econ is inhibited. ECON is only possible to select when both pack valves are open and the auto controlled cabin temp is within a preset range from the selected temp.
If an external air con unit is supplying ventilated air, what precautions must you take and why?
must open avionics hatch to prevent pressurisation of aircraft that prevents opening doors and windows.
alternative open sliding window before it is connected
What would you do to reduce cabin air temperature during ground ops and initial flight?
- before landing start the APU
- select the APU off shortly before TO
- during ground ops with cabin air supply select the recirc fans off if OAT is above 15 degrees
- during ground ops keep blinds closed
- select air con ECON mode off when passengers are boarding
What is normally operating maximum differential pressure as applied by the controller?
7.46psi
At that max differential pressure by the controller, what is cabin altitude at 35000?
8000ft
What is the differential pressure limited by the outflow valves?
7.65psi and cabin alt 12000 +- 1500ft
What is the altitude limiter set to?
cabin alt 12000 +- 1500ft
What warnings is there of excessive cabin altitude?
Level 3 alert CABIN ALT when above 10000ft
How is the fuselage protected aginst negatvie pressure?
via two inward pressure relief valves
