Today's Message Index:
----------------------
1. 06:19 AM - Re: Relay for Critical Power Feed (Eric M. Jones)
2. 07:59 AM - Re: Re: Relay for Critical Power Feed (Robert L. Nuckolls, III)
3. 08:19 AM - Re: Re: Relay for Critical Power Feed (Robert L. Nuckolls, III)
4. 08:46 AM - Re: Relay for Critical Power Feed (Eric M. Jones)
5. 09:05 AM - Re: Relay for Critical Power Feed (Eric M. Jones)
6. 09:14 AM - Re: Relay for Critical Power Feed (Eric M. Jones)
7. 09:45 AM - Re: Re: Relay for Critical Power Feed (Robert L. Nuckolls, III)
8. 10:05 AM - Jabiru 2200 voltage regulator (Charles Deiterich)
9. 12:00 PM - Re: Re: Relay for Critical Power Feed (Robert L. Nuckolls, III)
10. 12:00 PM - Re: Re: Relay for Critical Power Feed (Robert L. Nuckolls, III)
11. 12:07 PM - Jabiru 2200 voltage regulator again (Charles Deiterich)
12. 01:02 PM - Re: EXP 2 Bus workaround (Ken)
13. 03:00 PM - Re: Jabiru 2200 voltage regulator again (Robert L. Nuckolls, III)
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Subject: | Re: Relay for Critical Power Feed |
Don't use Type-70 Stancore-White-Rodgers-Emerson-Tyco contactors in your aircraft.
The reasons are plentiful: They have a 122 deg F maximum ambient. They are
not water or fuel proof, they won't open against high currents or voltages. They
are position sensitive and have low G-withstands. Disregard the fact that
they have been used and failing for many years. There are better ways to go. Bob
N. and I have argued this for years. Here are some excerpts from the archives:
--Relay mounting. Type 70 Stancor Rodgers White Emerson Tyco. See:
http://www.alliedelec.com/Images/Products/Datasheets/BM/STANCOR/Stancor_Industrial-Control_5760005.pdf
So the manufacturer says, "mount plunger vertical, cap down". I checked
into the engineering data on this part and of course the corporate
conglomeratization has destroyed the engineering knowledge that built the
part. The manufacturer PROMISED they'd get back to me.....BUT It's not DO-160 bubela.
And it's only 122 deg F max operating temp. Etc. etc.
I spent many hours tracking down the designers of this Stancor-White-Rogers Emerson
Tyco Type-70. The only info that remains available seems to be the present
specs. The available newly produced Type-70 specs simply make it unsuitable.
Will it work, Yes. Will it fail? Yes, sooner than you'd like. It is entirely
possible that Cessna had a custom model. Is Cessna still using these? Possibly,
but certificated a/c tend to use old original technology until it bleeds. There's
no reason you should follow them.
The Kilovac Czonkas II's are made in many types. There is a marine model too that
is perfectly usable. (Blue Sea Systems p/n 9012) But I don't have stock in
Kilovac. There are many makers of newer stuff [Gigavac has come out with similar
contactors].
For my airplane, I'll use a Flaming River Battery switch if I can, and an EV200
otherwise....
ps: Guess how Kilovac and Gigavac clamp coil voltages generated from the collapsing
magnetic field? That's right...internal bidirectional zeners.
"Everything you've learned in school as "obvious" becomes less and less
obvious as you begin to study the universe. For example, there are no
solids in the universe. There's not even a suggestion of a solid. There
are no absolute continuums. There are no surfaces. There are no straight
lines."
- R. Buckminster Fuller
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=410914#410914
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Subject: | Re: Relay for Critical Power Feed |
At 08:18 AM 10/20/2013, you wrote:
>
>Don't use Type-70 Stancore-White-Rodgers-Emerson-Tyco contactors in
>your aircraft. The reasons are plentiful: They have a 122 deg F
>maximum ambient. They are not water or fuel proof, they won't open
>against high currents or voltages. They are position sensitive and
>have low G-withstands. Disregard the fact that they have been used
>and failing for many years. There are better ways to go. Bob N. and
>I have argued this for years. Here are some excerpts from the archives:
"Better" is non quantitative. Just a few weeks ago
I received a failed, 70-series contactor removed from
a 70's model Cessna. The owner believed that it was
the original contactor. We did a tear down and discovered
that indeed, the contacts had become intermittent due
to corrosion on contacts exacerbated by ingress of moisture.
Mechanically the device was intact and functional . . .
after 30+ years of service.
Emacs!
Here's the mating set of contacts . . .
Emacs!
For a device that has been operated for 30+ years
"outside the spec sheet" envelope of limits it looks
pretty good to me. Would this Cessna owner be well
advised to install something "better"?
If "better" means that some other device will not succumb
to moisture (sealed contact chamber) and it has higher
ambient temperature ratings, then yes, this carry-over from
the 1940's has some peers with improvements that have
evolved over time . . . often crafted to meet the needs
of a more antagonistic environment.
But when cherry-picking of features that are "better"
becomes a driving force in our decision making processes,
then other authors on this List could opine that one
should avoid the IO-360 in favor of some newer
technology. Or perhaps we are well advised to abandon
panel mounted switches . . .
We gave up these switches
Emacs!
in favor of these . . .
Emacs!
For reasons that are fairly obvious. But consider
the constellation of simple-ideas that come with
the use of this part in your airplane:
Emacs!
There are 10 new metallic joints added to every
current carrying path by the use of these switches.
That's a fist-full of new opportunities for failure.
But each opportunity for failure is exploited by
environmental conditions and craftsmanship of the
installer.
These switches HAVE suffered some interesting
failures . . .
Emacs!
Question: Have switches of this genre ever bubbled
to the surface as a hazard so egregious as to generate
an AD against hundreds of thousands of such devices
flying for the past 70 years?
This switch has suffered that dubiou honor . . .
Emacs!
Every owner of a Baron or Bonanza has a new item
on his/her worry-list due to an un-foreseen deficiency
in the design . . . a deficiency that took decades
of field service before it bubbled up and people-paid-
to-worry took notice.
Even people-paid-to-worry have not banned the humble
ol' workhorse that is the 70-series contactor from
flying aboard airplanes. We can sing the ballad of
dueling specsheets but the bottom line is that this
product has a SERVICE HISTORY that demonstrates it
to be good value. I.e. performance traded against
cost of ownership while being attentive to
increased risks.
Since we're ALL building failure tolerant electrical
systems I can confidently suggest that consideration
of "better" contactors is driven more by our desire to
own and drive a Benz as opposed to a Ford . . . in spite
of the fact that both vehicles have high order
probability of getting us from point A to point B over
15 years and 200,000 miles at low risk . . . but with
markedly different costs of ownership.
Everything Eric has offered is true. The point of
this discussion . . . indeed the point of this List
is to sift the simple-ideas of any recipe for success
and make decisions based on cost of ownership weighed
against risk while sprinkling in some personal
preferences for V-Power or EXP-Bus in with the gaggle
of fuses and toggle switches. Just as S-K vs.
Harbor Freight tools are judged in the marketplace,
the value of a recipe-for success in our airplanes is
demonstrated in the air.
It's not WHAT we choose to use but the UNDERSTANDING
we bring to airplane to keep OPERABILITY high, RISKS
low while fitting COST of ownership to our own bank
accounts. The 70-series contactor has demonstrated
itself not to be a black hat lurking behind a rock
awaiting the opportunity to give you a bad day in the
cockpit. In 50 years of hammering on airplanes I can
confidently assert that the greatest risks for failure
to perform are human factors issues of installation,
maintenance or operation. Failure to perform based
inattention to specifications is VERY low on the list
things cause pilots to break a sweat while airborne.
Failure tolerant design strives to make any failure
a MAINTENANCE and COST OF OWNERSHIP issue as opposed
to a reason for breaking a sweat.
Bob . . .
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Subject: | Re: Relay for Critical Power Feed |
>
>I spent many hours tracking down the designers of this
>Stancor-White-Rogers Emerson Tyco Type-70.
Those guys died years ago . . .
> The only info that remains available seems to be the present
> specs. The available newly produced Type-70 specs simply make it
> unsuitable. Will it work, Yes. Will it fail? Yes, sooner than you'd like.
Quantify "sooner" and "like" . . . and lay foundation
for those numbers.
>It is entirely possible that Cessna had a custom model.
They did not. Everything Cessna purchased in those
days were catalog items folded into the qualified
parts stream by virtue of words and illustrations
on a piece of paper (we called them C-Drawings).
Beech did the same thing on the W-31 breaker-switches.
I did the same thing at Electro-Mech.
But when C-H was selling thousands per year to
Beech and Cessna versus hundreds of thousands per
year to customers unwashed by the FARS, who do you think
drove design decisions?
>Is Cessna still using these?
I'll have access to Cessna's great data-base-in-the-sky
in a few weeks. I'll see what is being offered as spares
for a 1970 C-172.
>Possibly, but certificated a/c tend to use old original technology
>until it bleeds.
Does the IO-360 bleed? Has the lead-acid
battery been relegated to the pages of
aviation history? Has the incandescent
landing light been pried out and replaced
with LED as a hazard to the airframe and
occupants?
>ps: Guess how Kilovac and Gigavac clamp coil voltages generated from
>the collapsing
>magnetic field? That's right...internal bidirectional zeners.
We explored the value of Benz versus Ford style
coil suppression about 13 years ago. I went to the
bench and did qualitative and quantitative measurements
on the differences in performance and benefits derived
therefrom. Did you find errors in either my process,
measurement or reasoning?
http://tinyurl.com/nva2xdy
http://tinyurl.com/25wjo7w
http://tinyurl.com/jwxxav8
Bob . . .
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Subject: | Re: Relay for Critical Power Feed |
Your photo of the 30 year old contactor discloses: 30 years ago they looked like
they were built better. The one you show is not the same one that is being used
now.
I stand my ground: Published specification for the Type-70 contactor say not to
use it in the applications for which it is being used. Regardless of the fact
that one can get away with it, better solutions are at hand.
> Does the IO-360 bleed? Has the lead-acid battery been relegated to the pages
of aviation history? Has the incandescent landing light been pried out and replaced
with LED as a hazard to the airframe and occupants?
>
Strawman arguments Bob. You can do better.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=410920#410920
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Subject: | Re: Relay for Critical Power Feed |
Attached disassembled Type-70 (minus cap).
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=410921#410921
Attachments:
http://forums.matronics.com//files/type_70_411.jpg
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Subject: | Re: Relay for Critical Power Feed |
Attached disassembled Type-70 (minus cap and copper coil). A long cost-cutting
way down from the part you show.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=410923#410923
Attachments:
http://forums.matronics.com//files/type_70_119.jpg
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Subject: | Re: Relay for Critical Power Feed |
Been having some problems with cut-n-paste between PhotoShop
and my email client . . . the email client doesn't always
keep the ducks lined up. The workaround seems to be to save
the image to hard drive and then import to the email client as
a file . . .
Reposted with corrected images . . .
At 08:18 AM 10/20/2013, you wrote:
>
>Don't use Type-70 Stancore-White-Rodgers-Emerson-Tyco contactors in
>your aircraft. The reasons are plentiful: They have a 122 deg F
>maximum ambient. They are not water or fuel proof, they won't open
>against high currents or voltages. They are position sensitive and
>have low G-withstands. Disregard the fact that they have been used
>and failing for many years. There are better ways to go. Bob N. and
>I have argued this for years. Here are some excerpts from the archives:
"Better" is non quantitative. Just a few weeks ago
I received a failed, 70-series contactor removed from
a 70's model Cessna. The owner believed that it was
the original contactor. We did a tear down and discovered
that indeed, the contacts had become intermittent due
to corrosion on contacts exacerbated by ingress of moisture.
Mechanically the device was intact and functional . . .
after 30+ years of service.
Emacs!
Here's the mating set of contacts . . .
Emacs!
For a device that has been operated for 30+ years
"outside the spec sheet" envelope of limits it looks
pretty good to me. Would this Cessna owner be well
advised to install something "better"?
If "better" means that some other device will not succumb
to moisture (sealed contact chamber) and it has higher
ambient temperature ratings, then yes, this carry-over from
the 1940's has some peers with improvements that have
evolved over time . . . often crafted to meet the needs
of a more antagonistic environment.
But when cherry-picking of features that are "better"
becomes a driving force in our decision making processes,
then other authors on this List could opine that one
should avoid the IO-360 in favor of some newer
technology. Or perhaps we are well advised to abandon
panel mounted switches . . .
We gave up these switches
Emacs!
in favor of these . . .
Emacs!
For reasons that are fairly obvious. But consider
the constellation of simple-ideas that come with
the use of this part in your airplane:
Emacs!
There are 10 new metallic joints added to every
current carrying path by the use of these switches.
That's a fist-full of new opportunities for failure.
But each opportunity for failure is exploited by
environmental conditions and craftsmanship of the
installer.
These switches HAVE suffered some interesting
failures . . .
Emacs!
Question: Have switches of this genre ever bubbled
to the surface as a hazard so egregious as to generate
an AD against hundreds of thousands of such devices
flying for the past 70 years?
This switch has suffered that dubiou honor . . .
Emacs!
Every owner of a Baron or Bonanza has a new item
on his/her worry-list due to an un-foreseen deficiency
in the design . . . a deficiency that took decades
of field service before it bubbled up and people-paid-
to-worry took notice.
Even people-paid-to-worry have not banned the humble
ol' workhorse that is the 70-series contactor from
flying aboard airplanes. We can sing the ballad of
dueling specsheets but the bottom line is that this
product has a SERVICE HISTORY that demonstrates it
to be good value. I.e. performance traded against
cost of ownership while being attentive to
increased risks.
Since we're ALL building failure tolerant electrical
systems I can confidently suggest that consideration
of "better" contactors is driven more by our desire to
own and drive a Benz as opposed to a Ford . . . in spite
of the fact that both vehicles have high order
probability of getting us from point A to point B over
15 years and 200,000 miles at low risk . . . but with
markedly different costs of ownership.
Everything Eric has offered is true. The point of
this discussion . . . indeed the point of this List
is to sift the simple-ideas of any recipe for success
and make decisions based on cost of ownership weighed
against risk while sprinkling in some personal
preferences for V-Power or EXP-Bus in with the gaggle
of fuses and toggle switches. Just as S-K vs.
Harbor Freight tools are judged in the marketplace,
the value of a recipe-for success in our airplanes is
demonstrated in the air.
It's not WHAT we choose to use but the UNDERSTANDING
we bring to airplane to keep OPERABILITY high, RISKS
low while fitting COST of ownership to our own bank
accounts. The 70-series contactor has demonstrated
itself not to be a black hat lurking behind a rock
awaiting the opportunity to give you a bad day in the
cockpit. In 50 years of hammering on airplanes I can
confidently assert that the greatest risks for failure
to perform are human factors issues of installation,
maintenance or operation. Failure to perform based
inattention to specifications is VERY low on the list
things cause pilots to break a sweat while airborne.
Failure tolerant design strives to make any failure
a MAINTENANCE and COST OF OWNERSHIP issue as opposed
to a reason for breaking a sweat.
Bob . . .
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Subject: | Jabiru 2200 voltage regulator |
I have Jabiru 2200 serial # 988 which has the 10 amp alternator.- I have
the circuit diagram of the Kabota regulator.- Is there a writeup on how t
he regulator works?- It appears to have a differential amplifier to sense
the bus voltage and the then compares it to the AC coming from the alterna
tor.- I just don't understand how the zener diode provides a reference wi
thout a resistor to control the current through the zener and also how the
AC wave is compared to the reference.- But then again I have always have
had problems with PNP circuits.=0AChuck D.
Message 9
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Subject: | Re: Relay for Critical Power Feed |
At 11:10 AM 10/20/2013, you wrote:
>
>Attached disassembled Type-70 (minus cap and copper coil). A long
>cost-cutting way down from the part you show.
Really?
Are we privy to the conversations that transpired
during the last 50 years worth of engineering/management/
manufacturing/marketing meetings wherein the design
features of this product like were decided?
I'll invite our readers to review the library of
70 series photos at http://tinyurl.com/kcc26jt
These photos only go back to about 1960 . . . it seems
likely that a 1940 tear-down would show yet other
differences.
I would guess that this product line has
enjoyed a host of cost-cutting changes. Advancements
in materials and automation are nearly always
responsible for reductions in cost and/or improvements
in meeting design goals.
But consider that of the trio of failure teardowns
illustrated in the library of pictures, 2 failures
were the result of assembly error . . . a human
factor I cited earlier today. The third failure
occurred at or beyond any practical expectations
for service life on the product . . . the thing
operated as designed and expired gracefully
(random intermittent). Further it was not a player
in the classic trio of conditions that precede
so many sad events in aviation and elsewhere.
You seem to use the phrase "cost cutting" as
an epithet. I have participated in dozens of
tasks where cost-cutting was a mission
imperative. However, in no instance was degradation
of service life or performance considered a
component of the acceptable solution. More often
than not, the upgrade reduced costs while improving
on the value of the product.
Bob . . .
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Subject: | Re: Relay for Critical Power Feed |
> > Does the IO-360 bleed? Has the lead-acid battery been relegated
> to the pages of aviation history? Has the incandescent landing
> light been pried out and replaced with LED as a hazard to the
> airframe and occupants?
>
>Strawman arguments Bob. You can do better.
Okay, strike that paragraph. What about the others?
Bob . . .
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Subject: | Jabiru 2200 voltage regulator again |
I have Jabiru 2200 serial # 988 which has the 10 amp alternator.- I have
the circuit diagram of the Kabota regulator.- Is there a writeup on how t
he regulator works?- It appears to have a differential amplifier to =0Ase
nse the bus voltage and the then compares it to the AC coming from the alte
rnator.- I just don't understand how the zener diode provides a =0Arefere
nce without a resistor to control the current through the zener =0Aand also
how the AC wave is compared to the reference.- But then again I have alw
ays have had problems with PNP circuits.=0AChuck D.=0A=0A=0AFurther study s
hows that Q1 and Q2 are to light a low voltage lite and are not part of a d
ifferential amplifier.- Q3 and Q4 are for the regulator.- My comment ab
out the current limit on the zener still stands.- circuit is from: http:/
/www.aeroelectric.com/Pictures/Schematics/PM_Regulator/Kubota_Schematic.jpg
=0A=0AChuck D.=0A
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Subject: | Re: EXP 2 Bus workaround |
If this question was for Ken...
On my one off z14 architecture 4 cylinder soob, I run two ecu's all the
time, one off each little battery. Two sets of injectors. Whichever set
of injectors is fed +12 volts flows fuel. If both are on by mistake the
engine loses some power but continues to run but a bit rough. I'm happy
with two switches for this. I don't need or want one either/or switch
although initially I was thinking that two mechanically interconnected
switches might be OK.
Similar with ignition. Whichever set of DIS coils is fed +12 volts feeds
the single plugs through MSD and homemade (polarity issue) HV coil
joiners. Both can be left on indefinitely or for landing and take off
but I only use one at a time.
In steady state cruise 18amps runs my airplane. That includes running
the VHF radio, transponder, intercom, engine monitor, gps, and maybe an
amp (or less) to the battery. If I did not have two alternators I'd size
the battery for about 15 amps for alternator failed operation. Injectors
are about 12 ohms and run 80% duty at full power and in my case about
50% duty in cruise. Ignition is about 5 amps at full power but a little
less in cruise. Similarly the injectors draw a little bit more at full
power but in total only maybe an amp or less difference between full
power and cruise for the complete system.
My system would certainly be overkill for most folks but it has some
unique advantages in terms of simple emergency procedures,
troubleshooting, and redundancy. With recycled parts, the dollar and
weight cost was trivial if not the labor. 530 flight hours on the Murphy
Rebel as of this morning.
Ken
On 19/10/2013 9:09 PM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 04:01 PM 10/14/2013, you wrote:
>
>> On Oct 14, 2013, at 12:16 PM, Ken wrote:
>>
>>> You are in the ballpark Fred but it's probably safe to round down to
>>> 20 amps for a no alternator battery life calculation.
>>
>> Ken...thank you for your "3rd party validation"...at this stage of the
>> game, I'd rather be conservative, and I'm looking forward to Bob's
>> assessment.
>
> I think I'm down to the last missing data point.
>
> How do you switch between ECU modules? Do you have
> a wiring diagram of this feature you can sketch or scan
> to share?
>
>
> Bob . . .
>
>
Message 13
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Subject: | Re: Jabiru 2200 voltage regulator again |
>
>Further study shows that Q1 and Q2 are to light a low voltage lite
>and are not part of a differential amplifier. Q3 and Q4 are for the
>regulator. My comment about the current limit on the zener still
>stands. circuit is from:
>http://www.aeroelectric.com/Pictures/Schematics/PM_Regulator/Kubota_Schematic.jpg
Yes, the circuit was dissected into two
functions at:
http://tinyurl.com/c8usyw2
http://tinyurl.com/c6doa97
. . . and you're right. The base-emitter junction of
Q4 in series with the hopefully small dynamic resistance
of the zener places the transistor at serious risk. This design
would not even come close to passing DO160 input voltage
tests. But then, not many garden tractors are subject
to the kinds of trash on the bus as airplanes.
I've not seen a schematic for a PM regulator that
offers warm-fuzzy feelings to an airplane jockey.
These bang-bang regulators have proven quite sufficient
for the lawn equipment markets and few folks have
complained about them in airplanes . . . at least
few to none here on the List. They may have a field
service history one step above dismal but not articulated
here.
If you're pondering a DIY project for a PM regulator,
consider adding some impedance in series with the
base of Q4. It doesn't need to be very big. The way
this thing is wired, the zener's operating current
is VERY low . . . a milliamp or less. Also poor design
practice . . . this is not up on the knee for predictable
conduction at the rated voltage. So 100 ohms in series
would protect the transistor and have very little
effect on regulation.
An adjustable regulator might modify the input circuit
to include a potentiometer which would add useful
base current protection for Q4. If you're up to brass-boarding
some experiments, I've had a few ideas for an upgrading
of the circuit's performance.
Bob . . .
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