From: Larry <IIMI > To: "Jeffrey E." <jeevacation®gmail.com> Subject: Re: update Date: Sat, 14 Jan 2017 16:28:40 +0000 I;11 ask them,. Maybe, less air pressure into cabin due to reduced power setting, when power levers are up at cruise or climb, the outflow valve is exhausting air from engines overboard to maintain cabin pressure,. During decent, the outflow valve closes to maintain cabin PSI, since airflow from engines is reduced? Just a guess, I'll ask the experts Thx Larry Sent from my iPad On Jan 14, 2017, at 11:19 AM, jeffrey E. <[email protected]> wrote: question would be why is it like glass on descent On Sat, Jan 14, 2017 at 12:12 PM, Larry c wrote: Jeffrey interesting findings: 1-left engine is oscillating air pressure into the cabin while APU bleed air and engine bleed air are ON, while advancing the throttles, there is a check valve that prevents air from engine to back feed the air duct from APU into cabin,. Suspect faulty check valve,. Inspecting and removing check value for possible fault. 2-during low power setting idle engine, the conditioned air that comes out by your feet along lower cabin side wall is not working properly when selecting auto full cold., when you advance the power on engines, the air blows warm to hot air, even when full auto cold is selected,. In Manuel operations, it works Normal,. This could be our issue during your last flight from Paris to NY when you stated you couldn't control cabin temp properly., Mechanics are in constant communication with Tech ops for proper trouble shooting techniques for this item. Support in Brunswick has been great. Both could be contributing factors to our Vib issue i think? ***lust pulled plane into hanger to start sheet metal repair,. The trouble shooting of Cabin temp and check value will continue, since electrical wiring and Cabin temp probe checks can be done in hanger with aircraft power. 3- precooler and pylon area, Fan Air modulation controller appear be t