Today's Message Index:
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1. 06:46 AM - Re: troubleshooting help needed (Robert L. Nuckolls, III)
2. 07:27 AM - Re: troubleshooting help needed (Robert L. Nuckolls, III)
3. 08:03 AM - Re: Aircraft Part Fell From Sky (Eric M. Jones)
Message 1
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| Subject: | troubleshooting help needed |
At 03:10 PM 7/20/2012, you wrote:
>Bill,
>I am having a similar problem with my Lancair. The voltage seems to
>float up and down about a half volt and I have had problems with the
>transponder shutting down and the moving map resets. I hope my
>problem is your problem and someone has a solution.
>
>Bill B
>
If a .5 volt excursion is causing your electro-whizzies
to misbehave, there's something else going on.
While it's viscerally satisfying to see a bus voltage reading
stay locked down to within a tenth of a volt of the
set point, having it vary by 1/2 volt under repeatable
conditions should not be an operational issue.
Your bus voltage should fly somewhere north of 14.0
volts . . . 14.2 was the 'sweet spot' when I worked
at Cessna . . . 14.6 to as much as 15.0 volts seems
to show up in contemporary automotive products.
But 14.0 is the operating floor for making sure
that a battery gets topped off a short time
after takeoff.
If your transponder is qualified for use in a
type certficated airplane, it should operate without
complaint down to end-of-battery-life voltage levels
on the order of 11.0 volts. The moving map should
be similarly qualified. For these devices to complain
in concert suggests an intermittent condition that
drops to levels much below your panel displays for
bus voltage . . . a voltage level below battery
supply voltage even. Loose connection?
Bob . . .
Message 2
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| Subject: | troubleshooting help needed |
At 08:33 PM 7/20/2012, you wrote:
[Luckey]
Bob, is that correct - shouldn't Field & Bus voltage oppose each other?
i.e. as Bus voltage goes up, Field current should go down?
It depends on what is being held constant and what
is being adjusted.
If SYSTEM LOAD is the variable, then yes . . . the
REGULATOR senses an INCREASE in bus voltage and
reacts by REDUCING field voltage.
In this instance, we're observing changes in
system performance while the load is constant.
If the field voltage rises in concert with the
bus voltage, then the regulator is commanding
that rise due to internal failure or mis-information
in the voltage sense path and the alternator
is performing normally.
If the bus voltage falls while the field voltage
rises, then the regulator is flogging a crippled
alternator without success.
Bob . . .
Message 3
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| Subject: | Re: Aircraft Part Fell From Sky |
Two questions:
1) What are the materials? If the right hand stuff is steel, I'd have to wonder
if it was from a truck.
2) Depending on 1): How far from the I-60 Superstition Freeway is his house?
--------
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=378855#378855
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