Sounds like the outflow valves decided not to work that day. I've had them freeze shut, but that probably had more to do with the outside ambient temps and the humidity than anything else. This is Alaska!
they may have had to shut down the cooling packs due to the failure. I'm sure a mad dog driver might be able to shine some more light on the temperature situation.
|Quoting AAR90 (Reply 7):|
What "heat"??? Temperature has virtually nothing to do with pressurization.
Actually, heat has everything to do with pressurization. The aircraft is pressurized using bleed air off the engines which is of higher pressure than ambient and also very warm.
On the B1900, we heat the plane using bleed air and we can get it pretty darn hot. We control the temperature using a valve that bypasses the warm uncooled air by the cooling system and mixes it with the cooled air. Aircraft use various means to cool the air down to more survivable temps.
Most trasport category aircraft use air cycle machines. ACM's in my opinion are quite amazing pieces of machinery and can be quite complicated in design, but work on a very simple premise.
An ACM forces the air to work, nothing more. Since the air is a closed system, ie no energy is being added, it has to use some of its potential energy, which at the time some is in the form of heat, to work. It is also important to note that energy cannot be created or destroyed, it can only be transfered, see Newton about those laws.
The air goes to work, usually spinning a turbine, and the temperature is lowered as energy is transfered to the turbine.
Got to love science!
"A pilot's plane she is. She will love you if you deserve it, and try to kill you if you don't...She is the Mighty Q400"