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  #11  
Old 05-10-2019, 05:36 PM
Larry DeCamp's Avatar
Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
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Default Complexity vs reliability

I have pondered adding NC push buttons to the PMag 12v supply so I don’t have to kill my master to test the onboard source of the Pmag. Whether a 3rd switch contact ( previous comments) or sp push button, it is added points of failure.

Are contacts really a WEAK link at these power application .
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  #12  
Old 05-10-2019, 06:29 PM
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GalinHdz GalinHdz is offline
 
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Quote:
Originally Posted by Larry DeCamp View Post
I have pondered adding NC push buttons to the PMag 12v supply so I don’t have to kill my master to test the onboard source of the Pmag.
This is exactly how I have my dual P-Mag setup. With NC push button switches the power is off only when I have the button pressed. So impossible for me to forget or get it wrong.

FWIW; I push each switch before engine start to make sure they actually disconnect the power to the mags. Then I push each switch with the engine running to make sure the internal generators are working correctly. I monitor the power status to each P-Mag via my DYNON EMS display.



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Last edited by GalinHdz : 05-11-2019 at 05:52 AM.
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  #13  
Old 05-10-2019, 06:34 PM
Scott Hersha Scott Hersha is offline
 
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Location: Cincinnati, OH
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If they are a weak point then you could just pull the circuit breaker (if so equipped) to accomplish the same thing. Pullable circuit breakers are not meant to be switches, so I would assume their failure mode would be shorter than a switch, push button or otherwise. If your push button failed to the open position then you wouldn’t be able to start the engine. If it failed closed then you wouldn’t know it unless you are checking low RPM cut out. If the mag doesn’t shut down at very low RPM while holding the button in, then it has failed closed. Am I getting that right? I’m assuming a normally closed momentary push button switch. With dual Pmags this is a little easier to check without having the engine shut down and having to restart. Just make sure you ground the mag in this situation before re-instating power to the dead one.
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  #14  
Old 05-10-2019, 07:44 PM
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N941WR N941WR is offline
 
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It seams to me that if your P-mag switches are not on the Ship's Power & Ungrounded position for landing, then you missed something on your pre-takeoff checklist.

I have mine configured so that if the three position switches are all the way UP position, then you are ready to go. Simple ergometric panel design. Down is off, and the middle would be test. Everything is up and you are ready to go.

A push button switch to momentary drop power to the P-mags is a simple solution but takes more panel space.

Just a couple of things to think about as you design your panel.
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Last edited by N941WR : 05-11-2019 at 05:49 AM.
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  #15  
Old 05-11-2019, 05:47 AM
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Nihon_Ni Nihon_Ni is offline
 
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Quote:
Originally Posted by N941WR View Post
It seems to me that if your P-mag switches are not on the Ship's Power & Ungrounded position for landing, then you missed something on your checklist.

I have mine configured so that if the three position switches are all the way UP position, then you are ready to go. Simple ergometric panel design. Down is off, and the middle would be test. Everything is up and you are ready to go.
I'm using this solution with locking toggle switches to prevent inadvertently turning one off in flight. They're also on the side of my panel where it's unlikely that I would bump them.
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  #16  
Old 05-11-2019, 05:52 AM
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N941WR N941WR is offline
 
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Quote:
Originally Posted by Nihon_Ni View Post
I'm using this solution with locking toggle switches to prevent inadvertently turning one off in flight. They're also on the side of my panel where it's unlikely that I would bump them.
I used a recessed sub-panel to keep the switches organized and out of the way. (Probably won't work on an -8.)

Here is an old, pre SkyView, picture of what I'm talking about. It has turned out to be a GREAT setup!

(Click to enlarge)
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  #17  
Old 06-07-2019, 04:46 AM
WingsOnWheels WingsOnWheels is offline
 
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Quote:
Originally Posted by BMW_X6M View Post
Actually I described it incorrectly. DYNON is looking for a ground on the contact inputs, so I used two small relays. When de-energized they produce the ground for the contact inputs. The screen shows indicator lights.
You could also use a double-pole switch. One set of poles for the mag power, second set switched to ground for a contact input.
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  #18  
Old 06-07-2019, 09:57 PM
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Bill Boyd Bill Boyd is offline
 
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Never mind all that! Only one burning question, dangling for ages, matters in P-Mag world:

When will the 6-cylinder model actually come to market?
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  #19  
Old 06-10-2019, 02:48 AM
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KRviator KRviator is offline
 
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Quote:
Originally Posted by Bill Boyd View Post
Never mind all that! Only one burning question, dangling for ages, matters in P-Mag world:

When will the 6-cylinder model actually come to market?
I'd say they're too late now. Surefly have their 4 and 6 cylinder EI magneto-hole-mount replacements out now...$1500USD each, and STC'd for the certified crowd too.
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