Today's Message Index:
----------------------
1. 05:06 AM - Re: Alternator problem? (donjohnston)
2. 05:49 AM - Re: Alternator problem? (user9253)
3. 05:54 AM - Re: Re: Alternator problem? (Charlie England)
4. 06:36 AM - Re: Alternator problem? (user9253)
5. 07:31 AM - Re: Re: Alternator problem? (Robert L. Nuckolls, III)
6. 07:40 AM - Re: Re: Alternator problem? (Robert L. Nuckolls, III)
7. 08:01 AM - Re: Alternator problem? (donjohnston)
8. 08:07 AM - Re: Re: Alternator problem? (C&K)
9. 09:06 AM - Re: Re: Alternator problem? (Etienne Phillips)
10. 09:06 AM - Re: Alternator problem? (Robert L. Nuckolls, III)
11. 09:26 AM - Re: Re: Alternator problem? (Robert L. Nuckolls, III)
12. 09:46 AM - Re: Re: Alternator problem? (Robert L. Nuckolls, III)
13. 12:15 PM - Re: Alternator problem? (donjohnston)
14. 04:42 PM - Re: Alternator problem? (user9253)
15. 06:34 PM - Re: Re: Alternator problem? (Verso Electronics)
16. 08:22 PM - Re: Alternator problem? (Paul Millner)
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Subject: | Re: Alternator problem? |
> If we were conducting this investigation in B-31 at Beech (Flight Test) we would
get out a data acquisition system...
Hey Bob,
Yeah, my kingdom for a DAQ that I could put on this. :(
> Can you pair the ov trip even with any particular action elsewhere in the system?
No. Like I said, the engine runs thus far have all been short (~5 min) and I've
been focusing on fuel and temp related indicators.
The engine issues have been resolved so now the engine runs should be longer and
I should be able to better monitor the electrical side to identify if there's
an event which precedes it or if it's random.
Right now I'm trying to decide if I should pull the alternator or wait and see.
Thanks,
Don
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444084#444084
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Subject: | Re: Alternator problem? |
> As it has been explained to me, the voltage regulator is determining the fault.
The VP-X is reporting the fault.
Looking at the LR3C documentation, there is no output terminal dedicated to providing
an over-voltage warning. Therefore the only way that the LR3C can indicate
over-voltage is by the crowbar circuit shorting out terminal 6. If terminal
6 gets its power from the VP-X and not from a circuit breaker, then the VP-X
should report over-current, not over-voltage. I do not know how the VP-X works,
but expect that it monitors system voltage independently from the LR3C.
If the VP-X reports over-voltage, a troubleshooter might ask, is it telling the
truth or lying? What is the over-voltage setpoint? How long must the voltage
be over the setpoint before tripping? Can the pilot change the over-voltage
setpoint?
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444085#444085
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Subject: | Re: Alternator problem? |
On Sat, Jun 27, 2015 at 7:04 AM, donjohnston <don@velocity-xl.com> wrote:
> don@velocity-xl.com>
>
>
> > If we were conducting this investigation in B-31 at Beech (Flight Test)
> we would get out a data acquisition system...
>
> Hey Bob,
>
> Yeah, my kingdom for a DAQ that I could put on this. :(
>
>
> > Can you pair the ov trip even with any particular action elsewhere in
> the system?
>
>
> No. Like I said, the engine runs thus far have all been short (~5 min) and
> I've been focusing on fuel and temp related indicators.
>
> The engine issues have been resolved so now the engine runs should be
> longer and I should be able to better monitor the electrical side to
> identify if there's an event which precedes it or if it's random.
>
> Right now I'm trying to decide if I should pull the alternator or wait and
> see.
>
> Thanks,
> Don
>
>
Pardon my density, but with an externally regulated alternator, how is it
possible for the alternator itself to be the cause of overvoltage? Isn't it
just a few coils of wire on some iron? It can't produce any significant
voltage at all without field current supplied by the regulator, right? It's
hard for me to envision any fault within the alternator that would produce
*higher* than design voltage. Any short or open circuit inside the
alternator should produce either lower or no voltage output, unless I'm
missing something.
Charlie
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Subject: | Re: Alternator problem? |
Good question Charlie. I also want to know what can go wrong with an externally
regulated alternator that would cause over voltage.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444088#444088
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Subject: | Re: Alternator problem? |
At 08:35 AM 6/27/2015, you wrote:
>
>Good question Charlie. I also want to know what can go wrong with
>an externally regulated alternator that would cause over voltage.
>Joe
>
>--------
>Joe Gores
Cogent questions gentlemen. The short answer is,
it can't. The long answer is that the transfer
function of voltage control in some regulators
doesn't handle brush-bounce well. This can
COMBINE with poor design of the OV trip system
to create some vexing symptoms. I can relate a
first hand-experience with OV trips in brand new
airplanes that go back over 30 years . . . with
engineers in three institutions pointing fingers
at each other while your's truly kept reminding
them of the obvious. That problem was only
recently solved by a long recommended replacement
of a regulator that should not have been qualified
onto the airplane in the first place.
If and LR3 is manifesting poor response to
brush-bounce, this will be a first in my experience.
It would be the collision of THREE conditions, each
at the extremes of their production tolerances,
or perhaps a manufacturing error.
I think this quite improbable but easy to check
with the swapping of one of the two waring factions.
The regulator probably being the easiest. There
are some peek, poke and ponder exercises to
conducted before we play swap-tronics.
Bob . . .
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Subject: | Re: Alternator problem? |
At 07:04 AM 6/27/2015, you wrote:
>
>
> > If we were conducting this investigation in B-31 at Beech (Flight
> Test) we would get out a data acquisition system...
>
>Hey Bob,
>
>Yeah, my kingdom for a DAQ that I could put on this. :(
The Force is in sympathy with you. Paul Fisher
and I will be stirring this into the list of
things to do . . . as soon as we clear the decks
of another commitment . . . probably after
OSH. The availability of off-the-shelf DAS
hardware and supporting graphical user
interface leaves no excuses for not crafting
a suite of hardware that addresses capabilities
we've dreamed about here on the List for 20
years.
There's no 'hard' work to be done here . . .
only assemble off the shelf stuff into
useful tools. It's all about the packaging.
By the way, this is not a state secret project.
If any members on the List have ECB layout
capabilities and reasonable skills at slinging
solder, contact me off-list and we'll see how
your skill-set offer might fit into this
project.
I'm contemplating this becoming a tool for
DIY efforts, perhaps a tool that could be rented
and shipped around the country as needed, and
it certainly has possibilities as an article
for KitPlanes.
The time for OBAM aviation to acquire routine
access to low cost measurement tools arrived a few
years ago and we were asleep at the keyboard.
Bob . . .
Message 7
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Subject: | Re: Alternator problem? |
I'll try an answer with either what I know or what I've been told:
The VP-X monitors the system voltage. When it hits 32v, it shuts off the power
to the field and reports an overvoltage fault. (see attached)
I don't know exactly where it's monitoring the system voltage. I would guess at
it's connection to the system bus.
The only "adjustment" to the overvoltage trigger level is whether it's installed
in a 14v or 28v system. On a 28v system, the OV trigger is hard set at 32v.
Vertical Power offered to bench check the VP-X. But since this is early in the
game, I was hoping to get some more ideas and data before going down that road.
Speaking of data, I did run across this little guy:
DataQ Instruments DI-149
http://www.dataq.com/products/di-149/index.html?gclid=Cj0KEQjwk7msBRCJj67khY2z_NIBEiQAPTFjv9iqePcOkNiAMApB_amhAfmVZ-fp0KOI3tHOgpWA9VoaAnUa8P8HAQ
I'm wondering if it would be helpful to identify what's happening.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444092#444092
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Subject: | Re: Alternator problem? |
Instead of impossible, I'd venture 'incredibly unlikely'. As in more
probable that I'll be hit by lightning before I send this. However I can
envision a scenario where a stray bit of internal debris shorts some
alternator output over to the field coil. Even less likely here where
the situation appears to be intermittent.
The question was asked but since it is not even worth consideration at
this point, I'm going to add
do not archive
Ken
On 27/06/2015 10:29 AM, Robert L. Nuckolls, III wrote:
> At 08:35 AM 6/27/2015, you wrote:
>>
>> Good question Charlie. I also want to know what can go wrong with an
>> externally regulated alternator that would cause over voltage.
>> Joe
>>
>> --------
>> Joe Gores
>
> Cogent questions gentlemen. The short answer is,
> it can't. The long answer is that the transfer
> function of voltage control in some regulators
> doesn't handle brush-bounce well. This can
> COMBINE with poor design of the OV trip system
> to create some vexing symptoms. I can relate a
> first hand-experience with OV trips in brand new
> airplanes that go back over 30 years . . . with
> engineers in three institutions pointing fingers
> at each other while your's truly kept reminding
> them of the obvious. That problem was only
> recently solved by a long recommended replacement
> of a regulator that should not have been qualified
> onto the airplane in the first place.
>
> If and LR3 is manifesting poor response to
> brush-bounce, this will be a first in my experience.
> It would be the collision of THREE conditions, each
> at the extremes of their production tolerances,
> or perhaps a manufacturing error.
>
> I think this quite improbable but easy to check
> with the swapping of one of the two waring factions.
> The regulator probably being the easiest. There
> are some peek, poke and ponder exercises to
> conducted before we play swap-tronics.
>
>
> Bob . . .
>
> *
>
>
> *
Message 9
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Subject: | Re: Alternator problem? |
Hi Bob
Have you considered using the Red Pitaya as a base for signal gathering?
It's an open source DAQ that already has a lot of the hard work done. It's
not dirt cheap ($320) but may offer a quick route to a portable, rentable
or EAA chapter own-able device that would fit the bill.
Check out www.redpitaya.com
Thanks
Etienne
On 27 June 2015 at 16:39, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 07:04 AM 6/27/2015, you wrote:
>
> don@velocity-xl.com>
>
>
> > If we were conducting this investigation in B-31 at Beech (Flight Test)
> we would get out a data acquisition system...
>
> Hey Bob,
>
> Yeah, my kingdom for a DAQ that I could put on this. :(
>
>
> The Force is in sympathy with you. Paul Fisher
> and I will be stirring this into the list of
> things to do . . . as soon as we clear the decks
> of another commitment . . . probably after
> OSH. The availability of off-the-shelf DAS
> hardware and supporting graphical user
> interface leaves no excuses for not crafting
> a suite of hardware that addresses capabilities
> we've dreamed about here on the List for 20
> years.
>
> There's no 'hard' work to be done here . . .
> only assemble off the shelf stuff into
> useful tools. It's all about the packaging.
>
> By the way, this is not a state secret project.
> If any members on the List have ECB layout
> capabilities and reasonable skills at slinging
> solder, contact me off-list and we'll see how
> your skill-set offer might fit into this
> project.
>
> I'm contemplating this becoming a tool for
> DIY efforts, perhaps a tool that could be rented
> and shipped around the country as needed, and
> it certainly has possibilities as an article
> for KitPlanes.
>
> The time for OBAM aviation to acquire routine
> access to low cost measurement tools arrived a few
> years ago and we were asleep at the keyboard.
>
>
> Bob . . .
>
> *
>
>
> *
>
>
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Subject: | Re: Alternator problem? |
At 06:34 AM 6/26/2015, you wrote:
I'm in the process of trying to track down an over voltage fault.
So far the engine runs that I've been doing have been relatively
short duration (mostly around 5-10min) while I'm getting the engine
dialed in. On about 4 occasions I've noticed the alternator circuit
has faulted for "over voltage".
I'm running a 28v electrical system
VP-X Pro
B&C LR3C voltage regulator
Kelly Aerospace 50a alternator
Continental IO-550 engine.
Vertical Power and B&C have had me check a number things. All checks
have shown voltage levels, drops and wire resistance to be well
within parameters.
How are your LR3 and VPX system configured? The
LR3 is fitted with crowbar OV protection. If I
understand your symptoms, it's an OV sense and
protection function within the VPX that tripping?
Can you de-program the VPX ov function? Or raise
it's trip point to some big number? You don't need
TWO ov protection systems.
>B&C is recommending to pull the alternator and have it checked.
In the great spaghetti-mix that is aviation
accessories, marketing and business models,
it's difficult to keep track of who's alternator
is being built by whom and with what, if any,
improvements.
The alternators involved in the three-decade saga
of new airplane OV trips were the occasionally-unfair
targets of accusatory assertions . . . but they
DID demonstrate varying degrees of brush-bounce
that often faded to acceptable levels after the first
20 hours or so of operation. For a time, brand new
alternators were being pulled off engines to be
'broke in' on a test stand before being re-installed.
A poorly understood work-around for what was a fundamental
design flaw in the regulator.
The whole legacy family of gear-driven alternators
for Continental engines have been the subject
of numerous 'investigations' . . . to this very day
. . . in spite of the fact that the car-builders
put those issues to bed three or four decades ago.
Such is the plight of consumers deprived of choices
outside the bounds of the cookie-cutter TC airplane
business.
Given what I DO KNOW about that family
of alternators and what I DO NOT know about the
VPX OV sense and response philosophy, it may well
be that your symptoms have root cause in
conditions not unlike those I've described
earlier in this thread. The problem may have
nothing to do with the LR3 and everything to
do with a discontinuity in assembly of
simple-ideas that govern performance.
>I"m just wondering if anyone has run into anything similar with
>these alternators before I pull it ship it out.
I have seen NO requirements that quantify, put
limits on or offer diagnosis tools for the detection
of brush bounce in airplane alternators. I've never
been able to measure it on the test bench . . .
the only way I could strengthen the hypothesis that it
existed was to add a filter to the field terminals of
the alternator and demonstrating that the problem
went away.
The filter only protected the poorly designed
ov sense system from a noise that was common to
and present in most alternators as a matter of
simple physics . . . noise so small that it was
difficult to detect amongst the other noises (All
well within MIL-STD-704 recommendations).
Just for grins, we could craft a little filter
assembly to jury-rig to the back of your alternator.
This experiment is not without risk of the
various participants 'relaxing' because your
particular manifestation went away. If
brush noise is indeed root to your symptoms,
it's indication of a fundamental design deficiency
in the ov sense system . . . NOT THE ALTERNATOR.
Bob . . .
Message 11
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Subject: | Re: Alternator problem? |
At 10:06 AM 6/27/2015, you wrote:
Instead of impossible, I'd venture 'incredibly unlikely'. As in more
probable that I'll be hit by lightning before I send this. However I
can envision a scenario where a stray bit of internal debris shorts
some alternator output over to the field coil. Even less likely here
where the situation appears to be intermittent.
The question was asked but since it is not even worth consideration
at this point, I'm going to add
Actually, Mooney experienced just such an event
back about 1980. I recall peering into the teardown
of an alternator that should have got some
combination of craftsmen and inspectors fired.
So it's not totally outside the realm of possibility.
But yes . . . in this ISO9000 world of 'perfection'
it should be exceedingly remote.
I wish I could remember the name of the engineer
I interacted with at Mooney. A solidly grounded,
common sense fellow with an airs of personality
that put a lot of people off. He had a small, red,
rubber coated steel mallet on which he inscribed
the non de plume, "PATIENCE".
I never witness it personally, but he was renowned
for expressing occasional bouts of frustration
by abusing the corner of his desk with "Patience".
Indeed, there were markings in the finish that
attested to his vice. He proved to be one of my
most valuable collaborators over those years.
On numerous occasions since, I have wondered
if there would be value in acquiring a "Son of
Patience". On further reflection, pounding on
a conference room table with a red hammer these
days would probably get me a visit from a host
of stern faced folks 'concerned' about my ability
to integrate in the modern culture.
Bob . . .
Message 12
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Subject: | Re: Alternator problem? |
At 11:04 AM 6/27/2015, you wrote:
>Hi Bob
>
>Have you considered using the Red Pitaya as a
>base for signal gathering? It's an open source
>DAQ that already has a lot of the hard work
>done. It's not dirt cheap ($320) but may offer a
>quick route to a portable, rentable or EAA
>chapter own-able device that would fit the bill.
>
>Check out <http://www.redpitaya.com>www.redpitaya.com=C2
>
>Thanks
>Etienne
To be sure, you've discovered one of a host
of potential possibilities. My current thoughts
are based on a VERY low cost DAS device I mentioned
here on the List a few days ago.
http://tinyurl.com/nvduk9x
For what ever it may lack in capability, you
sure can't argue about the price . . . especially
since it comes with a capable graphical user
interface and writes data to tabular files
for analysis with other tools.
I'm thinking of dropping this device onto a
'mother board' fitted with, what we'll have to
deduce, a useful collection of signal conditioners
for voltage, current, pressure, temperatures, etc.
Theres a REALLY handy current transducer with
great accuracy and frequency response
http://tinyurl.com/p9fk8po
The 6A version is easily adapted to sense currents
from hundreds of milliamps to hundreds of amps. Voltage
signal conditioning is easy. Temperature is easy in
the realm of solid state tranducers up to 100C, but
a channel of K thermocouple data would probably be good
too.
Pressure 4-20 mA pressure transducers are COTS
items.
I've got $hundreds$ in DAS equipment on the
shelf that I've used to great advantage in the
TC world . . . but too complex to install/operate/
resolve in the OBAM world. This is an exercise
in extracting lab grade data from a KISS box.
Need to make this so $low$ and simple that fewer
folk in the OBAM market are put off by the expense
risk and willing to try it for themselves.
This is the rolling-stock-consist for a train of ideas in
the current pot of idea-stew. I'm 'seeing' a board
about 2.5 x 3.5 inches that would mount the pic-stick
and 5-8 channels of signal conditioning for a BOM cost on
the order of $50-60.
Bob . . .
Message 13
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Subject: | Re: Alternator problem? |
nuckolls.bob(at)aeroelect wrote:
>
> In the great spaghetti-mix that is aviation
> accessories, marketing and business models,
> it's difficult to keep track of who's alternator
> is being built by whom and with what, if any,
> improvements.
All I can say with certainty is that the P/N of the alternator is 646843. According
to what I've been able to determine it's a TCM 60a alternator. I was told
that line of business was sold to Kelly Aerospace.
> The alternators involved in the three-decade saga of new airplane OV trips were
the occasionally-unfair targets of accusatory assertions . . . but they DID
demonstrate varying degrees of brush-bounce that often faded to acceptable levels
after the first 20 hours or so of operation.
You just went over my head with "brush-bounce". :(
> Given what I DO KNOW about that family of alternators and what I DO NOT know
about the VPX OV sense and response philosophy, it may well be that your symptoms
have root cause in conditions not unlike those I've described earlier in
this thread. The problem may have nothing to do with the LR3 and everything to
do with a discontinuity in assembly of simple-ideas that govern performance.
If this means that it's possible that I did something wrong putting this system
together, there is absolutely no doubt about that! :)
If so, can you give me some idea of where I may have a disconnection in the "discontinuity
in assembly of simple-ideas that govern performance"
> Just for grins, we could craft a little filter assembly to jury-rig to the back
of your alternator. This experiment is not without risk of the various participants
'relaxing' because your particular manifestation went away. If brush
noise is indeed root to your symptoms, it's indication of a fundamental design
deficiency in the ov sense system . . . NOT THE ALTERNATOR.
I'm all for grins! Can you give me an idea where to get or how to build this filter?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444101#444101
Message 14
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Subject: | Re: Alternator problem? |
Directions for making a filter:
http://www.sanantoniohams.org/tips/whine.htm
> You just went over my head with "brush-bounce".
Alternators have bushes that ride on slip rings. If the rings are not concentric,
the brushes will move up and down in their holders.
> can you give me some idea of where I may have a disconnection in the "discontinuity
in assembly of simple-ideas that govern performance
I get the impression that Bob is inferring that he does not trust the VP-X.
I suggest that instead of pulling the alternator, that you replace the voltage
regulator with a generic Ford VR166 or equivalent. There is a list in Bob's book.
The over-voltage and low voltage features of the LR3 are not needed in your
application if the VP-X provides over-voltage and the EFIS gives low voltage
warning.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444104#444104
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Subject: | Re: Alternator problem? |
On Jun 27, 2015, at 4:40 PM, "user9253" wrote:
> The over-voltage and low voltage features of the LR3 are not needed in your application
if the VP-X provides over-voltage and the EFIS gives low voltage warning.
Does the VP-X initiate a crowbar in the presence of over-voltage, or simply report
it through alarm output?
Eric
Message 16
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Subject: | Re: Alternator problem? |
Bob,
In our '70's Cardinals, Cessna installed an electrolytic capacitor across the OV
unit to minimize such trips...
Paul
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