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Dear Pete/Group,
I rewired my pressurization - I am somewhat not able to test the system
completely on the ground (which I was told is not uncommon). I hopefully
fly soon - then I should know.
This is what I found out/wired mine - please advise if I am wrong:
Pin 4 and 13 on the outflow valve are doing the same thing - if they get
grounded the system will dump the cabin pressure
I used pin 4 for the airspeed/valve handle circuit.
I used pin 13 for the electrical manual dump switch.
The wiring diagram for pin 4 can only be used as a schematic - the logic
is wrong - the lancair manual shows it right: pin 4 is grounded when
airspeed is low AND the gear handle is down
The wiring diagram for pin 13 is correct - pin 13 is grounded when the
switch is closed.
I used the pin 13 as an ON/OFF switch for my pressurization and mounted
the switch up side down - I turn on the pressurization when I open the
switch
I hooked up my outflow valve to my vacuum pump circuit that I use for my
steam instrument gages (gyro etc.)
Thanks for your help
Ralf
-----Original Message-----
From: Pete Sinclair [mailto:pete@leapfrogventures.com]
Sent: Tuesday, March 22, 2011 9:01 AM
To: lml@lancaironline.net
Subject: RE: Pressurization
The wiring diagrams I have seen show the gear switch grounding pin 4 of
the pressure head for planes without vacuum, and pin 13 if you have
vacuum. I think this is backwards. Pin 4 opens a solenoid in the
pressure head that connects the vacuum port directly to the bellows.
This allows the vacuum to pull the bellows fully open (dump mode). So,
if you have vacuum, you want pin 4 grounded when on the ground and
taking off (to prevent the pop you get when going to full power). I
added a small electric vacuum pump to mine to do this that goes on
whenever pin 4 is grounded.
Pin 13 goes to a second solenoid in the pressure head, but I have yet to
figure out what it does.
Pete
-----Original Message-----
From: billhogarty [mailto:billhogarty@hughes.net]
Sent: Sunday, March 20, 2011 6:29 AM
To:
Subject: Pressurization
For Pete Sinclair:
Pete: Looks like you might be the expert on this topic. I was looking
for a preflight check but thought that the system was grounded thru the
gear down switch. Any help here??
Thanks, Bill Hogarty
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