Pneumatics And Air Conditioning Flashcards
How many bleed sources are there per engine?
2 (NL and NH)
When does Nh bleed air help to supply the pnuematic system?
when pnuematic pressure is below 55PSI in the air or below 65PSI on the ground
When does the 18PSI system recieve pressure
when the engine is on
BLEED HOT
bleed air exceeds 287 deg. valves auto close
If one bleed valve is closed, will pressurisation be affected?
No
What do the air conditioning packs provide?
conditioned air to the cabin and flight deck, air for pressurisation
If one air con pack is off will pressurisation be affected?
No
How many air con packs are there?
2
If both packs are off will pressurisation be affected?
Yes - no bleed air in
CABIN PACK HOT
1 pack air cycle machine exceeds 207deg or 75psi. Auto shutoff/valve close
FLT COMP PACK HOT
2 pack air cycle machine internal temp 207deg or 75psi. Auto valve shutoff
How is the Air conditioning system controlled in manual mode?
with the cold/hot toggles
How many outflow valves are there?
3 (2 AUTO rear, 1 manual front)
How are the rear outflow valves opened and closed?
using 18PSI against a spring, controlled by the pressure controller unit
What happens if the aircraft lands pressurised?
the cabin will climb at 600ft/min for 1min then dump (with less than 2.5PSI diff)
What is needed for DUMP valve switch to operate in the air?
switch needs to be powered, 18PSI air.
Normal max cabin pressure diff?
5.5PSI +-0.3
Max cabin diff (pressure relief valve)
5.95PSI
What does the manual knob do?
changes the forward outflow valve to alter cabin alt
What does the manual switch on the f/o side panel do?
fully opens the forward outflow valve (DUMP)
what are the 4 main modes of the pressurisation system?
AUTO, MAN, DUMP, CAB SET
Max cabin alt?
8000ft
How would you manually set a lower cabin alt?
Semi auto(cab set) - set desired cabin altitude (unpressurised at that level when on descent)
What is the cabin rate of climb and descent at the detent?
500ft/min climb, 300ft/min descent
What does the fault light mean on the pressure controller mean?
Pressure controller has failed. Rear valves fully shut
what will happen to cabin altitude if pressure controller fails?
cabin altitude will rapidly decrease until max diff is reached, and stay at 5.95psi.
CABIN PRESS
Cabin altitude exceeded 10000ft. Emergency descent to 10k or MSA.
Memory items EMERG descent?
Oxy Mask on
Mic switch mask,
pax signs on
emerg descent, accomplish A/req (P/L FI, C/L max, maintain Vmo)
In an electric failure, what positions do the compressor bleed valves default to?
NL open
NH closed
Which pack is selected when bleed set to MIN
Pack 2
DUCT HOT
outlet of a pack is over 88deg. Auto to full cold.
Where are the temp sensors for cabin temp?
by the CAPT feet, under 5A, At the outlet ducts
Which pack(s) work with the APU on?
Both when set to NORM
Why do we need to turn the APU bleed air off before opening engine bleeds?
There’s no one way valve so the pressure will cause APU to stall/surge
What bus is the Pressure controller connected to
L MAIN
Which valve(s) have the 5.95PSI regulator?
All 3
If you switch to manual pressurisation and the manual knob is fully anti-clockwise, what should you do first?
Bleed to MIN or off first (stops large drop in cab alt)
Will a pressure controller fault bring on the Master caution?
No
What is the Cabin PSI max on the ground?
0.5PSI
