Today's Message Index:
----------------------
0. 12:15 AM - Reminder (Matt Dralle)
1. 12:52 AM - Re: Z-16 (pestar)
2. 06:25 AM - Re: Re: Battery contactor versus circuit breaker (Robert L. Nuckolls, III)
3. 07:38 AM - Fuselink Link 14/10 AWG connection (Harold Lanfear)
4. 08:40 AM - Re: Fuselink Link 14/10 AWG connection (George, Neal E Capt USAF ACC 505 TRS/DOJ)
5. 10:08 AM - Toggle Switch Failures in Canadian C-152 (Robert L. Nuckolls, III)
6. 10:15 AM - Re: Fuselink Link 14/10 AWG connection (Robert L. Nuckolls, III)
7. 10:45 AM - Re: Fuselink Link 14/10 AWG connection (paul wilson)
8. 11:20 AM - Re: Fuselink Link 14/10 AWG connection (Robert L. Nuckolls, III)
9. 11:21 AM - Re: Adding crowbar to older Z-11 architecture (Robert L. Nuckolls, III)
10. 04:39 PM - Re: Fuselink Link 14/10 AWG connection (paul wilson)
11. 06:04 PM - Covering up the contactors (James Kilford)
12. 10:07 PM - Re: Covering up the contactors (Robert L. Nuckolls, III)
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Dear Listers,
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Message 1
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Go to http://www.narva.com.au/products/browse/relays, they have a range of relays with the diode built in at low cost. I am using them for OV protection as per Bobs diagrams.
Yep I know it is down under but the relays are manufactured in Europe.
Cheers
Peter Armstrong
Auckland, New zealand
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=318289#318289
Message 2
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Subject: | Re: Battery contactor versus circuit breaker |
>
>It really sounds from what I'm reading that a battery contactor is
>the more desirable and "elegant" solution from a number of different
>aspects, rather than a circuit breaker purely serving as "automatic"
>battery wiring protection.
>
>I know the diagram was only ever intended as a very rough guide for
>the builder, but I can only speculate why it was drawn with a
>breaker on the supply side instead of a battery contactor.
Most folks skilled at airframe and power plants
are not widely read or experienced in electrical
systems. While suggested architectures and diagrams
are always functional at some level, they almost
never embody the best we know how to do nor are
they tailored to the builder's mission profile and
design goals.
It's not uncommon to find 'suggestions' that really
stretch the imagination of the reader to deduce
the simple-ideas that support the feature's
incorporation.
Whether or not to go the contactor route is driven
by two major considerations. Location of the switching
device for convenience of operation and/or power
savings when the engine driven power source or
battery size is small. A 0.8A contactor current draw
is no big deal when a 60A alternator is keeping
the lights lit. But when the alternator is good
for say 8A or you're trying to extend battery-only
operations, elimination of a contactor has benefits.
So it isn't a one-size-fits-all thought exercise.
Bob . . .
Message 3
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Subject: | Fuselink Link 14/10 AWG connection |
I=92m following Bob=92s Z-13/20 circuit and ready to install the 14 AWG
fusible link in the 10 AWG feed to the Battery Buss. However, there are
no crimp connectors matching both sizes; can I solder this joint or are
there better ways? I don=92t have spade and socket terminals to match
and hate to make a purchase for just a couple of terminals. Thanks much.
Message 4
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Subject: | Fuselink Link 14/10 AWG connection |
Harold -
You have several acceptable options. Among them:
1. Solder the 10-ga to 14-ga junctions, support with heat-shrink & cover
with fiberglass tube.
2. Strip the 14-ga wire back twice as far as you normally would and fold
the stripped end back on itself to better fill the 10-ga crimp connector.
Heat-shrink and fiberglass tube as indicated in AEC.
neal
===================
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Harold
Lanfear
Sent: Friday, November 05, 2010 9:26 AM
Subject: AeroElectric-List: Fuselink Link 14/10 AWG connection
I'm following Bob's Z-13/20 circuit and ready to install the 14 AWG fusible
link in the 10 AWG feed to the Battery Buss. However, there are no crimp
connectors matching both sizes; can I solder this joint or are there better
ways? I don't have spade and socket terminals to match and hate to make a
purchase for just a couple of terminals. Thanks much.
Message 5
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Subject: | Toggle Switch Failures in Canadian C-152 |
The C-152 switches cited in the Canadian publication
have nothing in common with the failures we've been
discussing here on the List in recent years . . .
The failure modes we've considered have to do
with a riveted construction of the Carling switches
that have been used on light airplanes for about
50 years. We've also considered some poor joining
(crimps) in the wire grips of terminals.
http://www.aeroelectric.com/Mfgr_Data/Switches/Carling/Carling_F-series.pdf
Over time, something has changed in materials,
design or process that make these devices more vulnerable
to loss of contact between the various metallic
joints in the current carrying path. All of the
numbered features in this figure . . .
http://aeroelectric.com/Pictures/Switches/Toggle_Switch_with_Fast-On_Tabs.jpg
A number of readers have reported failures in
Carling switches with most occurring in the one
circuit that generally operates at significant
current flow all the time for day and night
operations . . . strobes.
The failures have generally demonstrated
a rise in joint resistance followed by heating
exacerbated precipitation of the failure . . .
http://www.aeroelectric.com/articles/Anatomy_of_a_Switch_Failure/Anatomy_of_a_Switch_Failure.html
The C-152 switches referenced in the article are
are smaller and a cut below the Carling, F-series
switches we've been discussing. I'm familiar with
them but do not know who made them. They ARE a much
less expensive switch but I don't recall that they
used the riveted construction common to the F-series
Carlings. I believe the construction of these switches
looks more like this:
http://aeroelectric.com/Pictures/Switches/Miniature_Rocker_Cutaway.jpg
No rivets, only a pair of moving contacts that
get the benefit of some sliding motion that
tends to improve contact performance compared
to contacts that are simply mashed together. It's
interesting that this design REDUCES number of
metallic joints in current path from 10 down to
5. Pretty slick little switch.
I captured the Canadian failure analysis
and started to sift if for salient data and
conclusions.
http://www.aeroelectric.com/articles/C152_landing_light_switch_failures.pdf
This document is only a small cut above the typical
dark-n-stormy night story found in legacy aviation
rags. These guys did a electron microscope and
spectrometer analysis of the gooey stuff on the
switch to decide that it was probably dust and
drippings from a fitting on the oil pressure gage above.
Availability and applications of whippy tools
does not automatically translate into better
conclusions and remedial actions. As soon as
the writer mentioned "no DC ratings", commented
on circuit breaker performance, and iced the
cake with recommendations for a 70A rated panel
mounted switch, the value of their subsequent analysis
stepped off into the weeds. See:
http://www.aeroelectric.com/articles/Switch_Ratings.pdf
The effects have rippled throughout the aviation
community.
http://www.cessna.org/public/saib/docs/saib-ce-09-42.pdf
http://www.cessna170.org/forums/download/file.php?id=1199&sid=8c7275731a2108c3bdd961d763760192
http://n631s.blogspot.com/2009/09/landing-light-switches.html
Bottom line was that the switches used in these
applications (whether the C-150/152 mini rockers
or the larger Carling F series) have a SERVICE LIFE
that is driven more by CHRONOLOGICAL AGE and ENVIRONMENTAL
CONDITIONS (dripping oil, dust, moisture, etc) combined
with a LACK OF ACTIVITY that tends to burn away corrosion
and contaminants.
Would the failure have been prevented by installation
of a superswitch?
http://aeroelectric.com/Pictures/Switches/Toggle_Switch_with_Mold-Captured_Terminals.jpg
It might have taken longer . . . but the switch would eventually
wear out and need replacement. The mode of failure would
probably have been less exciting. But these switches
are 10x the price of the devices used in tens of thousands
of production airplanes with a very low rate of spectacular
failures.
Light GA aircraft place unusual demands on switches. I've
been suggesting for nearly 20 years that the OBAM aircraft
owner/operator simply shotgun a new set of switches into
the airplane every 5 years or so. Costs $50 in parts
and a couple hours work. Can't do that on a TC aircraft
for less than an indentured servant contract on your
first born. Nonetheless, the spectacular failure of this 20+
year old switch covered with greasy dust was determined
to be "inadequate to the design".
For every one that HAS failed, there are thousands
of switches that have NOT failed. I personally witnessed
extensive "life cycle testing" of new switches in
Cessna's lab . . . a landing light was switched on/off
for thousands of times before any new switch was considered
"adequate to the design". But like all laboratory
testing adventures, stresses on the device during
testing had little relevancy to stresses experienced
in service.
Just how did these investigators EXPECT a switch
to fail? Some switches may fail passive but quite
often, they get hot and smell bad. This report
suggests that a device "adequate to the design"
would last until the airframe was scrapped or at
least not get hot and smell bad. Sorry my friend
but it just doesn't work that way.
Bottom line is that the vast majority of switch
failures being reported to those-who-know-more-about-
airplanes-than-we-do have reached end of life never
fully explored and recognized by the appropriate
recommendations in a service manual. The report was
also noteworthy in citing lack of maintenance
that did not at least clean up and fix leaks of
oil above the switch that most certainly exacerbated
an otherwise "normal" failure.
Well guess what? Cessna responded in the only way
they COULD. Limit service life to the high current
switches to FOUR years . . . not flight hours but
calendar service life. Something that could and
should have happened 30 years ago.
How should WE react to this? Periodic replacement
of highly stressed switches is a good idea. Cheap,
easy, effective. Also, fix oil drips and clean up the
mess . . . but YOU guys do that anyhow . . . right?
Use relays to buffer the current demands on panel
mounted switches? Good . . . but it drives up
parts count and cost of ownership. The switch
WILL probably run to life of the airframe while
you still do periodic replacement of relays.
A simple, low cost preventative maintenance program
based on understanding is the best way to keep
these things from happening in your airplane . . .
like periodic replacement of highly stressed switches.
Having said all that, know that the failures we've
discussed recently about switches and terminals used
to wire those switches are a completely separate
set of events and solutions unrelated to the Canadian
activity that seeded this thread.
Bob . . .
Message 6
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Subject: | Re: Fuselink Link 14/10 AWG connection |
At 09:26 AM 11/5/2010, you wrote:
>I'm following Bob's Z-13/20 circuit and ready to install the 14 AWG
>fusible link in the 10 AWG feed to the Battery Buss. However, there
>are no crimp connectors matching both sizes; can I solder this joint
>or are there better ways? I don't have spade and socket terminals
>to match and hate to make a purchase for just a couple of
>terminals. Thanks much.
Suggest you use a MAX 30 fuse and
mating in-line fuse holder
Emacs!
available from most big-box auto parts
stores.
Bob . . .
Message 7
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Subject: | Re: Fuselink Link 14/10 AWG connection |
NAPA is now selling the kind Bob likes. They have the double metal
that allows the insulation to be crimped. You need to crimp twice to
get both the wire and the insulation. They pass my pull test and grab
the 1/4" spade plenty hard. Try them before you buy the AMP ones. So
far just red and blue not yellow where I live. Check your store If
they have the yellow you will be good to go with a little heat shrink.
Maybe Bob will give us and evaluation?? HINT.
Paul
==============
At 07:26 AM 11/5/2010, you wrote:
>I'm following Bob's Z-13/20 circuit and ready to install the 14 AWG
>fusible link in the 10 AWG feed to the Battery Buss. However, there
>are no crimp connectors matching both sizes; can I solder this joint
>or are there better ways? I don't have spade and socket terminals
>to match and hate to make a purchase for just a couple of
>terminals. Thanks much.
Message 8
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Subject: | Re: Fuselink Link 14/10 AWG connection |
At 12:02 PM 11/5/2010, you wrote:
>
>NAPA is now selling the kind Bob likes. They have the double metal
>that allows the insulation to be crimped. You need to crimp twice to
>get both the wire and the insulation. They pass my pull test and
>grab the 1/4" spade plenty hard. Try them before you buy the AMP
>ones. So far just red and blue not yellow where I live. Check your
>store If they have the yellow you will be good to go with a little heat shrink.
>
>Maybe Bob will give us and evaluation?? HINT.
Hmmmm . . . do you have a manufacturer and part
number by chance? We might be able to learn a
lot from the manufacturer's data.
Bob . . .
Message 9
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Subject: | Re: Adding crowbar to older Z-11 architecture |
At 04:33 PM 11/4/2010, you wrote:
>
>I have been flying for several years with Z-11 (no alternator OV
>disc. contactor) and an internally regulated alternator. I would
>like to know whether the simple and inexpensive step of installing a
>crowbar OV module as in Z-24 will provide OV protection. I have read
>Bob's article on load dump damage and I am able to turn off my
>alternator with the panel "OFF/BATT/ON" switch.
>My thanks to Bob or anyone else who can answer my question.
The problem with adding ov protection for internally
regulated alternators is that there are failure modes
that cannot be controlled through the small wire.
So yes, some form of b-lead disconnect is called for
and Z-24 is one way to go about it. The load dump
thing is a bit of a red herring . . . first, there's
no NEED to flip the alternator on/off during normal,
loaded operations. Second, any IR alternator worth
it's salt will withstand a worst case load dump
many times in a row. See revision 12 chapter on
engine driven power sources in the 'Connection.
Bob . . .
Message 10
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Subject: | Re: Fuselink Link 14/10 AWG connection |
I am 1000 miles away from my shop, but I have a package of the new
style butt connectors in my truck. NAPA P/N 784331. They are reds
tranlucent plastic and have the extra metal extension. I use several
rachet crimpers and they all give a good result with these things.
Takes 2 crimps with my crimpers to grab theinsulation.
Branded by Balkamp (a NAPA house brand). Made In Taiwan
The other stuff in my truck are the cheepe 3M automotive stuff you
are fanmiliar with and they will not grab the insulation. However
they do give the soild crimp like your AMP tests.
Mabe the attached pic will reveal something?
At 11:17 AM 11/5/2010, you wrote:
><nuckolls.bob@aeroelectric.com>
>
>At 12:02 PM 11/5/2010, you wrote:
>>
>>NAPA is now selling the kind Bob likes. They have the double metal
>>that allows the insulation to be crimped. You need to crimp twice
>>to get both the wire and the insulation. They pass my pull test and
>>grab the 1/4" spade plenty hard. Try them before you buy the AMP
>>ones. So far just red and blue not yellow where I live. Check your
>>store If they have the yellow you will be good to go with a little heat shrink.
>>
>>Maybe Bob will give us and evaluation?? HINT.
>
> Hmmmm . . . do you have a manufacturer and part
> number by chance? We might be able to learn a
> lot from the manufacturer's data.
>
>
> Bob . . .
Message 11
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Subject: | Covering up the contactors |
Gents,
I have three contactors mounted on the engine side of the firewall,
along with a battery. Everything else (regulator, busses, etc.) is
inside the cabin. Is there any value in covering up my contactors, or
are they alright as they are?
Many thanks,
James
Message 12
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Subject: | Re: Covering up the contactors |
At 08:01 PM 11/5/2010, you wrote:
>
>Gents,
>
>I have three contactors mounted on the engine side of the firewall,
>along with a battery. Everything else (regulator, busses, etc.) is
>inside the cabin. Is there any value in covering up my contactors, or
>are they alright as they are?
Here's the firewall of an A36 Bonanza.
http://aeroelectric.com/Pictures/Wiring_Technique/A36_Firewall_A.jpg
http://aeroelectric.com/Pictures/Wiring_Technique/A36_Firewall_B.jpg
with contactors, fuseblocks, current limiters, etc
hung out in behind Continental and everybody.
I think your electro-whizzies will be fine without
extra-ordinary cover.
Bob . . .
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