'The minimum of 290 kts is "the minimum airspeed required to maintain appropriate cabin pressure differential with the outflow valve in the full open position" according to our Flight Manual.'---another mistery
This does not appear in our books,and I think it's definetly wrong.
With 'Pack trip Off" the pack valve is closed,so no matter how much air is going through the ram door.Also the Mix valves,and all valves in the ACM can be in any position,no matter what.As I said,the pack valve,which is before the pack will be closed.
There is a difference between mix valves fail in HOT position (It happed to me once--very hot day on the cocpikt,no matter the speed) and the pack trip off closed.It nthe second case the pack is closed,not working.
The answer to your question is,probably ,that by keeping more than 290 kts,the plane will be ventilated at an increased rate(due to depression created on different areas on the fusselage,that creates suction,and removes hot air from inside.Why hot air? Because of all the electrical wires and instruments,I guess)
So,I guess,It's a question of aerodinamics rather than valves or packes.The air will enter through some valve and exit by another due to pressures created moving fast.
You won't be able to mantain any cabin pressure differential with the valve open,no matter what speed you keep.If anybody knows different ,I stand corrected,but then,there would've been no emergency descent,right? Just increase speed,and it's ok.Nonsense
