Ventilation Flashcards
Open-circuit configuration- describe.
What threshold temps?
Open system is while on the ground and temp> 9 degs (decreasing) or > 12 degs (increasing) or avionics duct temp > 40 degs.
The skin air inlet valve is open and the blower pushes air through the avionics equipment and cockpit panel ventilation, before the extract fan pushes the air out of the skin air outlet valve (overboard).
Closed-circuit configuration- describe.
What threshold temps?
Closed system is while on the ground and temp<9 degs (decreasing) or <12 degs (increasing) or avionics duct temp < 40 degs.
The skin air inlet valve is closed, so air is fed from the avionics bay through the ‘skin exchange outlet bypass valve’ and the blower pushes air through the avionics equipment and cockpit panel ventilation, before the extract fan pushes the air to the cargo underfloor via the ‘skin exchange inlet bypass valve’ or around the ‘skin heat exchange’ circuit back to the blower fan.
Intermediate configuration- describe it? Which temp thresholds?
Intermediate configuration is while airborne and temp > 32 degs (decreasing) or > 35 degs (increasing).
The skin air inlet valve is closed, so air is fed from the avionics bay through the ‘skin exchange outlet bypass valve’ and the blower pushes air through the avionics equipment and cockpit panel ventilation, before the extract fan pushes the air out of the ‘skin exchange inlet bypass valve’ OR overboard (skin air outlet valve particularly open) OR around the ‘skin heat exchange’ circuit back to the blower fan.
What happens when blower or extract fault?
When blower or extract pbs are set to ‘OVRD’, the system goes in to closed configuration, with air being added from the air conditioning inlet valve.
When blower is set to OVRD, blower fan stops
When extract is set to OVRD, extract is controlled directly from the pb, both fans continue to run.
Smoke configuration- describe it.
When smoke detected in avionics, fault lights come on for blower and extract pbs.
When blower and extract set to OVRD, blower fan stops and cool air conditioning is added through the air cond inlet valve, which then goes through the avionics ventilation and cockpit panel ventilation before being exhausted overboard through the skin air outlet valve (which is partially open).
Controller failure?
In case of a controller failure, fault lights come on and BLOWER and EXTRACT fault lights come on, and are set to OVRD.
It is basically the smoke configuration, but the skin air inlet, exchange isolation valve and exchange outlet bypass valve remain in the last position before failure.
