Mailing List lml@lancaironline.net Message #54370
From: Craig Berland <cberland@systems3.net>
Sender: <marv@lancaironline.net>
Subject: [LML] Airspeed sensing switch: Pressurization
Date: Sat, 30 Jan 2010 14:41:20 -0500
To: <lml@lancaironline.net>
Re: [LML] Re: Airspeed sensing switch: Pressurization

Do you guys have much luck opening the door before you deflate the door seal?  I tried to pressurize the cabin with the door seal deflated…..didn’t have much success with 32 InHg manifold pressure.  I suspect with the engine at idle, it wouldn’t be much better.

 

Craig Berland

IV-P    N7VG

 

Paul pointed out the obvious:   a door with even 1 psi behind it is dangerous.  (1 psi times 600 or so?   I don't have the measurements)

 

So I do buy the argument that at low throttle settings, and under normal circumstances, you aren't going to have much residual pressure in the cabin.   But there are lots of possible failure modes here:  a) pressure controller malfunction b) pressure controller set way below landing altitude c) exhaust valve is not operating correctly - not enough cabin exchange rate.  These may argue for the pressure switch

 

The suggestion I like the best is "check cabin pressure before opening the door".

 

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