Craig,

I tested my ability to open the door of my IV-P with the seal inflated, just to see if I could do it in an emergency (yes-definitely), but it risks blowing out the seal, so I wouldn’t recommend doing it, at least on a regular basis. As you would expect, the door is difficult to open, as you’re working the latches against the pressure seal…hard on the latches and other equipment as well.

You may have noticed that a large amount of air passes the door seal when it’s not inflated. I actually leave it un-inflated for drawing cooling air from the tail NACA duct through the cabin when I’m not running the air conditioner. Therefore, it’s not possible to achieve any pressure differential within the cabin with the seal deflated.

One issue I have is operating at low altitude (e.g the pattern) with the seal inflated and the engine at low power. The air collected at the NACA inlet on the vertical stab pushes the cabin flapper valve open (as designed) and temporarily pressurizes the cabin a small amount. It then closes and the pressure dissipates, allowing it to open again. The result is a surging that’s uncomfortable on your ears. There are a couple of ways to prevent this in my airplane, but it’s a bother nonetheless. My best solution so far is to turn on the air conditioner, which diverts the tail scoop air away from the cabin and across the a/c condenser coil and then out the back.  (Note that my a/c installation/configuration is a personal design, probably unique in the fleet, so this won’t work for others.

Bob