Malibu Pressure Update (Part II)

G'day Zeir,Thanks for that. So the ECS switch will probably open a constant mass flow control valve supplying bleed air to the air cycle machine which supplies conditioned air into the cabin. If this is the switch you were referring to as being switched on at 12000 ft then I can well understand the pressure bump you referred to. Air cycle machines spin at unbelievably high rpm's and supply a huge airflow.Thanks for your personal experience story; it certainly added an interesting aspect to this thread.Cheers,Roger @YSSY