I have an Aerostar 700P with a Dukes Electric Outflow Valve PN 5362-00-01. This valve only uses electrical signals to communicate with the controller and pressurizes to 5.5. I know the valve has a problem because one of the gears fell off the valve and was rattling around inside the can. We put the gear back on but because it came off the shaft I am assuming that there is more going on with the valve. Dukes is unhelpful (they can't repair it or look at it till next year) but if any of you have a source for one I would appreciate it.

As they say, once you have pressurization you can never go back, and flying around at 8K and 9K is not near as fun.

Appreciate any help you may have.

I don't have any experience with these guys, but its worth a call...

http://www.cabinpressurerepair.com/home.html

Eric

Have you contacted Jim Christy at AAC? Surely he can help you..

Yes, Jim has been very helpful but it is a Duke's issue.

Not sure if you can post but try the lancair site. Lancairtalk.net. All the IV-P use an electric dukes valve. Being an experimental plane there are a few people on there that have learned a lot about them and have some other sources for repair.

Eric,

Alan Speakmaster (Master Aviation) is very knowledgeable on the inner working of the pressurization controller.

(203) 790-5226

Forrest

Thanks Forrest, The controller is fine and the outflow valve is fine. I really just need to know how to recalibrate the valve after the gear fell off. I will check with Alan.

If any of you have the Dukes electric pressurization I have involuntarily become a resident expert because the people at Dukes were more useless than _____ on a nun (sorry if that was offensive but Dukes brings it out of me).

Here is how the system works. The controller and the outflow valve have matching potentiometers that determine the position of the valve. If your valve becomes uncalibrated (i.e. the controller thinks you are at a different altitude than you are) the calibration was actually pretty easy assuming you have a little redneck in you. You will have to first remove the outflow valve and the cover screws that face the AC unit in the cabin because you cannot remove them with the outflow valve in place.

All you have to do is set the controller at the altitude where you are at field elevation and confirm that the motor is not running. You will get no voltage being sent down the motor wires if you do this right. Then remove the gear on the outflow valve itself and go fly the plane with a safety pilot. Climb to the altitude where you want pressurization to start and then rotate the valve stem until the pressurization starts. At that point pull the breaker so that the potentiometer doesn't move and install the gear. I did this and hit the nail on the head on the first try.

The gear came off the shaft initially because if the potentiometer loses a connection to the outflow valve it will never sense that it arrived at the proper place. Apparently when the shop was doing my avionics work they wire tied the wires for the JPI to the harness for the outflow valve. The weight of the JPI harness was enough to disconnect the potentiometer wire in the outflow valve (but not the hot wire or the ground). I did notice that the cannon plug on my outflow valve had been assembled by someone who clearly did not have the right tools. Three of the five pins were crimped incorrectly (these were the potentiometer wires) leading to a bad connection. This may account for why my valve had previously been back to Dukes on four occasions in its 11 year life.

Now off to drink a martini and celebrate.