I prefer inflatable door seals as the cabin is not only a little quieter, there is typically less cold air entering the cabin around the edges of the doors.
To succeed with this idea, I ordered the “hardware” from Lancair Aircraft – pump, hoses, pressure switch, fittings, check valve, and pneumatic switch since Velocity Aircraft didn’t have a source for the parts. (I think they do now.)
This diagram is straight out my Legacy Builder’s Manual. I used it as reference for what parts to order from Lancair.
The first seals we used on the doors caused too many door fit problems. These had already been installed on another single engine airplane, but weren’t working out as well as hoped. They were installed on the fuselage door flanges. I decided to install on the door flanges. Hopefully, it would go smoother. It didn’t. After a lot of effort trying to make these seals work, the doors were still too difficult to close. Not good.
Luckily, Scott Swing was able to find seals from the same company but that were smaller. They were also available in black which looked much better than the gray ones that we had been trying to make work. This smaller seal also uses smaller diameter tubing which was also better, as the smaller tube was easier to route from the top of the cabin to the door, and fit into the gap much better.
Notice the black outline on the door. That is the seal. Notice the small orange tubing. That is the door seal pump output line. We routed this tubing via the pilot side door frame and thru the ceiling. Notice the black trim around the door jamb. That is the standard Velocity door trim.
We installed the seal on the door flange, rather than the fuselage. This is better as the seal is not subject to wear and tear from climbing in and out of the airplane. This allowed us to use the standard Velocity finish trim pieces on the door jambs. These have a very nice look. I’m glad we were able to stick with them.
The pneumatic switch is quite an interesting little device. In the off position, the pump doesn’t run as the tube between the pump and the switch is sealed. Also, this position vents the door seal to the outside which causes it to depressurize. When turned to the on position, it closes the vent and connects the pump tube to the seal. When pressure is obtained, the pressure switch turns the pump off. Rather ingenious.
The green light indicates the seal pump is running. Once the seal is pressurized, the pump should remain off.
For longevity of the door seal itself, it is good practice to depressurize the seal prior to opening a cabin door.
