Today's Message Index:
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1. 05:46 AM - Light Speed Ignition with OV (ROGER & JEAN CURTIS)
2. 07:08 AM - Re: Light Speed Ignition with OV (Robert L. Nuckolls, III)
3. 03:39 PM - Head sets, iontercoms and Hand helds (jtortho@aol.com)
4. 06:00 PM - Re: Light Speed Ignition with OV (user9253)
Message 1
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| Subject: | Light Speed Ignition with OV |
There has been discussion recently about Light Speed Ignition with built
in
OV protection based on a phone conversation with Light Speed. And then
someone posted an excerpt from the installation manual which reads in
part:
"Input voltages above 35 volts or reversed polarity will cause system
damage. For this reason it is mandatory that all aircraft using Plasma
CD
Ignitions are equipped with over-voltage protection in their alternator
charging system(s)."
I interpret this to mean that there is no crowbar over-voltage
protection
built into the Light Speed Ignition. Otherwise, how could it be damaged
if
high voltage is shorted by internal OV protection? And why would it be
mandatory that the aircraft electrical system be equipped with OV
protection
if it is already built into the ignition? I suggest that there was a
misunderstanding in the conversation and that Light Speed Ignition
systems
do NOT have built-in crowbar over-voltage protection. The company
should
issue a written statement to clarify this issue. Otherwise prospective
customers might not want to buy their products if there is a perceived
danger that a charging system failure could stop the engine.
Joe
This is not a perceived danger, as you stated, but a real actual failure
reported by more than 1 lister. I agree that the company should issue a
statement to clarify their design goals. In the mean time, it appears
that
pilots should be aware of this potential problem and the power to the
Light
Speed Ignition systems should be fed through an easily accessible in
flight
circuit breaker.
Roger
Message 2
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| Subject: | Re: Light Speed Ignition with OV |
At 07:36 AM 2/8/2009, you wrote:
>
>There has been discussion recently about Light Speed Ignition with
>built in OV protection based on a phone conversation with Light
>Speed. And then someone posted an excerpt from the installation
>manual which reads in part:
>"Input voltages above 35 volts or reversed polarity will cause
>system damage. For this reason it is mandatory that all aircraft
>using Plasma CD Ignitions are equipped with over-voltage protection
>in their alternator charging system(s)."
>I interpret this to mean that there is no crowbar over-voltage
>protection built into the Light Speed Ignition. Otherwise, how
>could it be damaged if high voltage is shorted by internal OV
>protection? And why would it be mandatory that the aircraft
>electrical system be equipped with OV protection if it is already
>built into the ignition? I suggest that there was a
>misunderstanding in the conversation and that Light Speed Ignition
>systems do NOT have built-in crowbar over-voltage protection. The
>company should issue a written statement to clarify this
>issue. Otherwise prospective customers might not want to buy their
>products if there is a perceived danger that a charging system
>failure could stop the engine.
>Joe
>
>This is not a perceived danger, as you stated, but a real actual
>failure reported by more than 1 lister. I agree that the company
>should issue a statement to clarify their design goals. In the mean
>time, it appears that pilots should be aware of this potential
>problem and the power to the Light Speed Ignition systems should be
>fed through an easily accessible in flight circuit breaker.
This is one example of the important activities
for crafting and qualifying systems on
TC aircraft. This exercise offers decades of valuable
lessons-learned. The conversations that have
evolved around this topic are excellent examples
of how much "wobble" there is moving toward
complete understanding when we're not privy to
the details of a particular product's design.
On the TC side of the house it's not uncommon for
an OEM airframer to have complete sets of drawings
for as-supplied products in the "vendor files".
Of course, these are protected under the standard
non-disclosure agreements. Access to these files
is a critical component of seamless system
integration and troubleshooting of fielded
systems.
Not having access to internal details gives rise
to discussions not unlike those we're having now
about Lightspeed . . . and those we've had in the
past about critical characteristics of IR
alternators.
The point I've emphasized in all of these
discussions is that intimate knowledge of the
inner workings of a product is absolutely required
for competent systems folks to do their job.
The marketing hype and 4-color brochures are
useless when it comes to qualifying a device on the
aircraft and/or preventing/fixing problems in the
field.
There is risk when a customer is forced to
"interpret" the meaning of words to arrive at some
rudimentary understanding. Lightspeed has a
free-marked duty to give you lucid answers to
all of your questions . . . just as you have
a right to reject their product based on
perceptions of value and risk. Risk pushed
upon you as a product of holding critical details
incommunicado is not acceptable.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 3
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| Subject: | Head sets, iontercoms and Hand helds |
This seems that it should have an easy answer, but In this area I am a neophyte.
In my 2 seat? project, I have a Avcom AC6PA intercom. I was going to run the output
of a Nav 122 into a switch on the audio input of the intercom.? This should
let me monitor this as Nav 1 without an audio?panel.
I also have a hand held, the sporty? JD200.
What would be the repercussions of wiring the hand held as one of the passenger
head sets.? The real goal is being able to hear over the intercom.? The? hand
held speaker port expecting to see a 150 ohm head set, but would instead see
the 5 volt bias? for the microphone.? Would this work at all , or over/under drive
the intercom.? I am afraid I don't know what amplitude of signal is expected
or supplied.? Going in the other direction would be a similar mismatch.? The
hand transmitter would be seldom used , in my plan, so driving that via the
intercom would be less important, and I would expect to use the integral PTT.
So would this work, or would I make expensive smoke?
JimT
Message 4
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| Subject: | Re: Light Speed Ignition with OV |
Thanks to Bob and Roger for the informative replies.
Roger, You mentioned other postings about over-voltage conditions disabling the
Lightspeed ignition. I would like to read about them if you happen to have a
link to the posting. I do not read AeroElectric everyday and missed the postings.
I did read about a Lightspeed ignition that failed because of overheating.
Thanks, Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=229278#229278
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