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02-26-2013, 05:36 PM
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Join Date: Jan 2006
Location: Orange County CA
Posts: 646
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Expensive
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I don't know what type of switch you're looking at, and from which vendor. But a basic Honeywell TL-series SPST switch goes for about $20.
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The B&C switches are about $5 each. If you are concerned, you can buy several spares for replacement down the road, and still save money.
That's the beauty of building an RV. Everyone gets to choose what to buy and install. Have fun. Buy reliable parts from respected vendors, and be happy with your selection. It's your airplane. You only have to please yourself.
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Peter McCoy
RV9A N35PM S/N:91335
First Flight: April 2013
Hobbs: 400 hours after Oshkosh 2017
www.myrv9.com
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02-26-2013, 05:59 PM
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Join Date: Feb 2009
Location: San Jose, CA
Posts: 164
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I heard 'lectric Bob speak at Oshkosh a few year ago about exactly this. He advocated using inexpensive, off the shelf parts like B&C sells and then replacing the switches after 10-15 years. For $100, you can replace all the switches in a typical homebuilt periodically and achieve system reliability that likely exceeds that of expensive mil-spec switches.
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02-26-2013, 06:15 PM
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Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,687
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Quote:
Originally Posted by beav
I heard 'lectric Bob speak at Oshkosh a few year ago about exactly this. He advocated using inexpensive, off the shelf parts like B&C sells and then replacing the switches after 10-15 years. For $100, you can replace all the switches in a typical homebuilt periodically and achieve system reliability that likely exceeds that of expensive mil-spec switches.
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The reality is no one replaces their "equipment" until it fails.
Use whatever you want, quality stuff usually costs more, but to me (and most of my customers will agree) it's worth it.
8 years, 1300+ hrs, 100% Dispatch reliability.
__________________
Walt Aronow, DFW, TX (52F)
EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
Last edited by Walt : 02-27-2013 at 06:37 AM.
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02-26-2013, 07:15 PM
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Join Date: Mar 2007
Location: Sonoma County
Posts: 3,821
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Lectric Bob..... also explained why push on connectors were a superior electric connection.
I purchased all of my switches from Granger rated for AC. I used these switches in my propane truck. This switch was cycled over 40 times a day, five days a week for fifteen years. And NOT one failure. This was an AC rated switch on a DC load. Part # 4X849 about $6 each.
__________________
VAF #897 Warren Moretti
2019 =VAF= Dues PAID
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02-26-2013, 07:53 PM
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Join Date: Jan 2006
Location: Dallas, TX (ADS)
Posts: 2,180
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Quote:
Originally Posted by beav
For $100, you can replace all the switches in a typical homebuilt periodically and achieve system reliability that likely exceeds that of expensive mil-spec switches.
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How do you figure that? If you have less reliable switches in there, and you replace them, how does that make them suddenly more reliable? Does replacing a part suddenly make the replacement item more reliable then the original?
I look at switches the same way as any instrumentation - it needs to work. If it doesn't matter if it works or not, you probably don't need it and should consider getting rid of it.
TODR
__________________
Doug "The Other Doug Reeves" Reeves
CTSW N621CT - SOLD but not forgotten
Home Bases LBX, BZN
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02-26-2013, 08:07 PM
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Join Date: Nov 2012
Location: Northern Nevada
Posts: 137
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Getting back to the original question:
Both push on and screw on terminals work fine and do not often fail.
I use both on my aircraft. Both work!.
When do I use screw on .. when I have a linear group of switches or circuit brakers that are all tied together by a copper bus. You drill holes, then use screws though the bus (with lock washers). If you use pushons you will have many more connections that could fail.Also, not as clean looking.
Just my 0.02 cents.
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02-26-2013, 10:45 PM
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Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
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Forces and spec sheets....
The 1/4 inch Faston PIDG terminals are great, but some care needs to be taken installing and removing the terminal from tabs.
For 22g wire the minimum commercial crimp "pull out" force is 8 pounds, while the maximum "pull the terminal off the tab" force can be as high as 18 pounds for the first use.
So... don't pull on the wire to remove a terminal from a tab....
Numbers here -
http://www1.futureelectronics.com/do...CS/42067-1.pdf
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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02-27-2013, 12:11 AM
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Join Date: Feb 2006
Location: San Diego, CA, U.S.A.
Posts: 770
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Component reliability, system reliability, and dispatch reliability
Quote:
Originally Posted by beav
I heard 'lectric Bob speak at Oshkosh a few year ago about exactly this. He advocated using inexpensive, off the shelf parts like B&C sells and then replacing the switches after 10-15 years. For $100, you can replace all the switches in a typical homebuilt periodically and achieve system reliability that likely exceeds that of expensive mil-spec switches.
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I gotta disagree with 'lectric Bob on this one. No matter what type of switch you use, replacing them all unconditionally at some arbitrary interval is not only unnecessary and wasteful in time and money, but it also would likely hurt system reliability more than it could ever help because of infant mortality and other related effects.
All switches can fail. Not necessarily at the same rate, nor for the same reasons, but they all can and will eventually fail (though most will outlive your airplane). System reliability is a function of the reliability of the individual components under their respective operating conditions, but also the design of the system to prevent single component failures from taking down the system or large portions thereof. That's a whole topic in itself that I won't get into here. But the point I wanted to make is the following.
Even if you assume for the sake of discussion that the commercial grade switches from B&C are equally as reliable as the milspec switches (doubtful, but assume it for the sake of discussion), the milspec switches still have the advantage of ubiquity as I described above (post #7). Walt hit the nail on the head in referencing the objective of achieving good dispatch reliability. Part of that is reducing the failure rate by various means, including use of good quality of components. But another less obvious part is ensuring serviceability and minimizing down time when failures do occur, both at home and away, both at present time and in the future for the lifetime of the airplane. When you experience a failure 10 years from now and 1000 miles away from home (away from your personal stash of spare parts), the local mechanic or avionics shop is likely to have the standard milspec switches on hand, not the B&C flavor of the day from ten years prior. That's when that extra $100 spent upfront to use milspec switches in your panel (a drop in the bucket on a ~$100K airplane I might add) will have more than paid for itself, in getting you back on your way with minimum delay.
P.S. There was recently a thread discussing standard external power connectors versus Piper-style connectors and other possibly effective but non-standard contrivances, where I advocated using the standard connector for essentially the same reasons I'm advocating the milspec switches here. Dispatch reliability. When the s*** hits the fan at the most inconvenient time and place, consider what resources will be most likely available to get you back on your way.
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02-27-2013, 06:33 AM
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Join Date: Oct 2007
Location: Littleton, CO
Posts: 388
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Thank you for all your inputs which I do value?. In the interest of fairness, I plan to use half screw on and half Faston. I also intend to complete the rest of my airplane without priming any more.
I?m now schizophrenic and so am I
__________________
Bob Markert
Littleton, CO KBJC
Reserve Grand Champion Oshkosh 2016
Renegade Opposing Solo pilot and other Dirty Odd Jobs
http://www.rmrairshows.com/
2019 dues paid
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02-27-2013, 06:37 AM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by az_gila
The 1/4 inch Faston PIDG terminals are great, but some care needs to be taken installing and removing the terminal from tabs.
For 22g wire the minimum commercial crimp "pull out" force is 8 pounds, while the maximum "pull the terminal off the tab" force can be as high as 18 pounds for the first use.
So... don't pull on the wire to remove a terminal from a tab....
Numbers here -
http://www1.futureelectronics.com/do...CS/42067-1.pdf
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When I was ripping my panel out for the upgrade, I decided to "test" the quality of my crimps I had done on all of the ground wires going to the forest of tabs ground bus.
I pulled about 30 of them off the forest of tabs by pulling on the wire. Not a single one of them pulled the wire out of the connector. Some had to be pulled very hard to get em to come off.
Sold me on good connectors, good crimp tools and Faston connections.
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