Fred:  Posting here is a trial for me--I am good at stirring the pot I guess.  However since I have an unpressurized IV and have done the door seal thing I will swallow hard and share.

First some answers to unasked questions:  I flew without an inflating door deal for about 50 hours waiting to paint and to prove to myself the seal was necessary in an unpressurized IV.  It is!!  The CO and noise was prohibitive until the seal was installed.  Of course this was caused by the lower pressure inside the cabin, even with the vents open, sucking all things evil into the pilot's sanctuary.  Next the fit:  I did not do much to alter the fit of the molded door to the molded frame thinking the inflated seal would fill the 1/2 inch gap.  It does but after observing for about 150 flight hours I think the larger gaps around the corners (here the gap grows to nearly an inch) could have been worked a bit to get everything down to about a half inch.  Now your questions:

1.  Not sure exactly what you mean about the silicone tape step.  If you mean the extra seal that is sent with the kit and is applied to the door frame (as apposed to the inflating seal that is applied to the door) I did not use that seal and have never seen a IV with it installed.  If you mean using silicone tape to actually attach the inflating seal to the door well I used several alternatives but found that silicone RTV though messy was the only thing that holds the seal in place.

2.  I have varied the pressure in my seal and used a gauge to experiment.  20 psi is too much and makes my cabin snap, crackle and pop.  I have used as little as 8 psi but find the seal has problems expanding all the way into the gaps in the door corners--the reason for extra work here.  I now fly with 10 psi and all works fine, though the pump seems to blip on every few seconds during flight.  I think this a dead band problem with the pump's pressure switch and I may look for a switch with a greater dead band some day--hopefully before the pump burns out.

hope that is helpful and does not stir sleeping Hamids (I have no self control...)

paul, N94PT

 

I am about to install the pressurized door seal on my unpressurized LIV.  .

 

For my aircraft, I wonder if the mating silicone tape that is bonded to the door frame is truly required.  The greatest delta P I can imagine across the door is about 0.3 psi, far short of the 5.5 psi of the pressurized aircraft.  I can see that the silicone tape may be required to hold the door seal in place against the pressurization forces, but it seems like overkill for the unpressurized aircraft.

 

Earlier discussions suggested reducing the air pressure from 20 psi to about 11 psig (if I recall correctly) to extend the seal lifetime.  This was for pressurized aircraft.

 

Questions:

 

1)     Can I eliminate the silicone tape on the door frame and let the seal seat on the paint of the door frame?  Eliminating the silicon tape would save a step and provide a cleaner installation.

2)     Can I further reduce the required pressure?  I would think I could go to a low pressure (say 5-8 psi), flight test, raise it a bit if I get a leak, test again, etc.

 

Any of you non-pressurized guys have any advice or recommendations?

 

Thanks,

 

Fred Moreno