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  #61  
Old 05-13-2018, 11:37 AM
rv7charlie rv7charlie is online now
 
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Mark,

A multi-throw toggle switch is yet another single point of failure. If it physically breaks (yes, it happens), you could lose both pumps.
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  #62  
Old 05-13-2018, 11:58 AM
Mark33 Mark33 is offline
 
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Location: Baton Rouge, La.
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Quote:
Originally Posted by Mike S View Post
If you are running dual feeds and CB's, and switching with a toggle switch, why would you need the relay at all?

In the linked schematic the relay is used to switch from one pump to the other while using a single feed from a single CB.
The way Iím planning on wiring it will incorporate some redundancy. On one relay Iíll have 87 connected to one pump and 87a connected to the other pump. On the second really Iíll do the exact same thing. This way the B.M. can do itís thing with its automatic switching capabilities and if one of the paths of electricity is interrupted for any reason (C.B.,relay,etc.) the other C.B. and relay can take over full duty and continue to allow the B.M. to work as normal...including its automatic pump switching functions. So basically, 87 from both relays will go to one pump and 87a will go to the other pump....so Iíll have two relays and two different circuits/C.B. doing the job that one relay and one C.B. can do....but they will be a backup for each other in the event one of them were to fail. Iím also planning on incorporating an oil pressure sensor switch into the system so that while the toggle switch is in the pump1/auto position, and if thereís no oil pressure, the fuel pumps will automatically shut down. All modern automobiles have this safety feature built in, so that in an accident the fuel pumps donít continue to run and possibly spray fuel everywhere. This safety feature/switch will only affect the system when the toggle switch is in the pump1/auto position. By flipping the switch into the pump 2 position everything will work as normal.

Mark
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  #63  
Old 05-13-2018, 12:03 PM
Mark33 Mark33 is offline
 
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Quote:
Originally Posted by rv7charlie View Post
Mark,

A multi-throw toggle switch is yet another single point of failure. If it physically breaks (yes, it happens), you could lose both pumps.
Thatís a great point....and well taken, but Iím using top quality mil-spec switches and I think the simplicity of a single switch has merit....but I have thought about your exact point quite a lot.

Mark
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  #64  
Old 05-13-2018, 12:15 PM
rv7charlie rv7charlie is online now
 
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Well, even space-qualified stuff breaks. Surprisingly often.

One of the reasons I like the Aeroelectric Connection list so much is the basic philosophy that drives it. Bob emphasizes to not ask how reliable something is, but what happens when it breaks. If bad things would happen, then ask what could be done to create plan B. It's unreasonable to add spare wings, but an additional switch? Not hard at all. :-)

Worst thing (and I struggle with this) is the added *operational* complexity. That's multiplied if some other pilot needs to fly the plane.

Charlie
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  #65  
Old 05-13-2018, 12:31 PM
Mark33 Mark33 is offline
 
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Quote:
Originally Posted by rv7charlie View Post
Well, even space-qualified stuff breaks. Surprisingly often.

One of the reasons I like the Aeroelectric Connection list so much is the basic philosophy that drives it. Bob emphasizes to not ask how reliable something is, but what happens when it breaks. If bad things would happen, then ask what could be done to create plan B. It's unreasonable to add spare wings, but an additional switch? Not hard at all. :-)

Worst thing (and I struggle with this) is the added *operational* complexity. That's multiplied if some other pilot needs to fly the plane.

Charlie
Charlie,

My thoughts exactly!!....including me trying to fiddle with more than one switch in the event of an emergency. Heck, Iíll be doing good just to drive the thing to a safe landing. LOL!! But youíre point is well taken regarding Bobís line of thinking regarding ďwhat ifĒ. I think the way Iím going to be able to wire it, itíll default to one of the circuits to continue to be hot and at least one of the pumps to continue to run even if the toggle switch itself fails.

Mark
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  #66  
Old 05-13-2018, 12:46 PM
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rcpaisley rcpaisley is offline
 
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Location: Upland, CA
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Default pump backup

"I lost faith in Bus Manager when I saw it recommends both pumps share common wiring, circuit breaker, and relay."

As already stated:
If you want further pump power redundancy, simply add a toggle switch with its own power source to one of the pump 12v terminals - pretty simple.

The automatic pump management of the Bus Manager is a very nice feature.
As is the start batt select feature, and of course the redundancy of the essential bus. You lose all of this going another route.

Robert
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  #67  
Old 05-13-2018, 10:27 PM
svyolo svyolo is offline
 
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Robert;
Threads like this are the reason I am here. To learn. Very occasionally I might have something to add.

I am not a moderator, but to me your posts cross the line and actually detract from the thread.
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  #68  
Old 05-14-2018, 02:03 PM
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rcpaisley rcpaisley is offline
 
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Default svyolo

Hi Svyolo,
Sorry if we cross the line for you.

We have worked with more than 450 aircraft/builders now over the last 16 years.
Our only concern is safety. If we can help a few people avoid the mistakes that have been implemented before them, this is a well worthwhile effort in our estimation.

I fully realize that the din of opinion in internet forums can be overwhelming.
It is not always easy to discern the facts that sit between the endless lines of good intentions.

A very good place to start is to get information directly from suppliers who have been down these roads many times before and know their products well.

Robert
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  #69  
Old 05-15-2018, 07:07 AM
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DanH DanH is online now
 
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Quote:
Originally Posted by rcpaisley View Post
Our only concern is safety. If we can help a few people avoid the mistakes that have been implemented before them, this is a well worthwhile effort in our estimation....

A very good place to start is to get information directly from suppliers who have been down these roads many times before and know their products well.

Robert
Ok, so seriously....tell us what happened to these two.

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA
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  #70  
Old 05-15-2018, 11:07 AM
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rcpaisley rcpaisley is offline
 
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Default NTSB

As far as I know:
1. Voltage regulator failure leading to over voltage, dual lithium battery installation melt down, electrical system failure.

2. Non standard wiring installation, too small of a circuit breaker used on the injector circuit, injector breaker popped during low level (river following flight), hard landing.

Robert
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