> To: lml@lancaironline.net
> Date: Wed, 4 Sep 2013 07:42:10 -0400
> From: 2thman1@gmail.com
> Subject: [LML] IVP pressurization
>
> Having trouble getting my pressurization to work effectively.
> I did my best to seal the pressure vessel but never got above .25 PSID with my 6 horse shop vac. Used both pressure and vacuum to check for leaks. No smoke but used a down feather and then a stethoscope with tympanic membrane removed. Outflow valve is covered during these tests.
>
> After lots of frustration i hired a guy who has built and/or pressurized about a dozen IVPs to come take a look. He determined using smoke that there were a couple of slight improvements to be made mostly in the wire bundles through the aft pressure bulkhead and after doing this he declared the vessel seal very good.
>
> So we deduced that maybe the shop vac is not as efficient at blowing air as I thought, but my flying experience with the aircraft is that it doesn't do much better than the .25 PSID in flight up to 14.5K ft.
>
> Wondering why there is inadequate pressurization with a good pressure vessel leads to thoughts of outflow valve problems. I bought the device with the kit in 1996 so it occurs to me the valve could be dirty or rubber diaphragm could be failing, etc. I removed the outflow valve yesterday and tried to examine the parts. i lubricated the mandrel that the poppet valve slides on with a very small spritz of LPS1 lubricant in case there was stiction there. I did notice that with the poppet valve manually moved to the furthest closed position the diaphragm still had somewhere around a 1/32" gap at the seating perimeters. Should the air pressure in flight fill that diaphragm to close the gap or does this indicate the valve needs servicing?
>
> Finally is there a way short of the manual dump switch to keep the system from pressurizing better than what I see by mismanaging the controller? Am I just setting the pressurization up wrong? Have only been up to 3,000 ft elevation airports, (KRDM) and lower - most at sea level.
>
> Thanks for any help.
>
> John Barrett
>
> Sent from my iPad
>
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