A320 Avionic cooling logic

[b767300]

Hi all

Regarding Avionic cooling on A320 fleet

The FCOMS says

CLOSED CONFIGURATION (Flight and ground)

Flight phase
The threshold is
+35c and increasing
+32c and decreasing

Ground phase
The threshold is
+12c and increasing
+9c and decreasing

INTERMEDIATE CONFIGURATION (Inflight only)

The threshold is
+35c and increasing
+32c and decreasing

OPEN CONFIGURATION (On ground only)

The threshold is

+12c and increasing
+9c and decreasing



I do understand that the 3 degrees split is for the computer not to go crazy.

I am trying to visualize the above logic, any idea to simplify this ?

Highly appreciate your knowledge sharing.

[noughtsnones]

Open:
-This configuration is used if warm ambient conditions exist while the aircraft is on the ground.
-Outside air is drawn through the open inlet valve by the blower fan where it then passes around the avionics equipment.
-The extract fan then pulls the heated air and expels it out through the fully open extract valve.
-Avionics compartment air does not pass through the aircraft skin heat exchanger or the cargo under floor.

Intermediate:
-This configuration is used if warm ambient conditions exist during flight (airborne or thrust levers placed to a takeoff position while on the ground).
-The configuration is exactly the same as the closed configuration except that a small internal flap within the extract valve opens to expel some of the heated avionics compartment air overboard.


Closed:
-This configuration is used mostly during flight or if cold ambient conditions exist while the aircraft is on the ground.
-Avionics compartment air is cooled via an aircraft skin heat exchanger; air is circulated by the blower and extract fans.
-The inlet and extract valves remain closed.
-Air is expelled through the cargo under floor and out through the outflow valve.


A G00g1e search for "Quizlet A320 Air Systems mrdeerwood" found a text description, does my picture (incorporating a table of the thre possible heat sinks assist?http://i1007.photobucket.com/albums/af196/noughtt/A320avioniccooling_zpsf20d1d6e.png

[Swedish Steve]

Note that on the latest A320 the logic has changed slightly. Our last 3 aircraft delivered this year have a different setting for on the ground.
Before, on the ground, skin temp above 12deg and the inlet/outlet doors would open. On the new config they stay closed until the avionics cooling exhaust rises to 35 deg. So in European temps, the inlet/outlet flaps will not open normally on the ground.
The crew notice and ask questions.

[IFixPlanes]

The new behaviour comes with the new "comfort duct temperature sensor" (34HQ) in combination with an AEVC V07. Threshold is 40 °C.
See OIT 999.0042/14.