Today's Message Index:
----------------------
1. 06:17 AM - Split loom melting (Lapsley R. and Sandra E. Caldwell)
2. 07:53 AM - Re: Split loom melting (Robert L. Nuckolls, III)
3. 01:18 PM - Re: Split loom melting (Allen Fulmer)
4. 03:15 PM - Unhappy Instrumentation on Jabiru 3300 (Fiveonepw@aol.com)
5. 03:56 PM - Re: Split loom melting (Robert L. Nuckolls, III)
6. 04:27 PM - Re: [GRT_EFIS] Unhappy Instrumentation on Jabiru 3300 (James Clark)
7. 06:39 PM - EIS interference (Robert L. Nuckolls, III)
8. 07:15 PM - Re: EIS interference (Fiveonepw@aol.com)
9. 10:11 PM - Re: EIS interference (Robert L. Nuckolls, III)
Message 1
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| Subject: | Split loom melting |
I have experanced melting of some of the black split loom I used an
conduit to prevent wire chaffing in my engine compartment. One piese
that melted was 6 or 7 inches from the exhaust tube.
Note that this is a recent problem that has occured after I add some
additional heat shield due to heat discoloration on the inside of the
lower cowl,
Has anyone else had this problem?
Does anyone have any data on what temperatue exists in the engine
compartment?
As an aside I did some informal tests of the black split loom and it
burns and is not self extinguishing.
Are thre any good fire resistant alternatives?
Roger
Message 2
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| Subject: | Re: Split loom melting |
At 09:07 AM 10/5/2008 -0400, you wrote:
>Caldwell" <lrsecaldwell@earthlink.net>
>
>I have experanced melting of some of the black split loom I used an
>conduit to prevent wire chaffing in my engine compartment. One piese
>that melted was 6 or 7 inches from the exhaust tube.
>
>Note that this is a recent problem that has occured after I add some
>additional heat shield due to heat discoloration on the inside of the
>lower cowl,
>
>Has anyone else had this problem?
>
>Does anyone have any data on what temperatue exists in the engine compartment?
Temperatures under the cowl can range from ambient
(OAT at xx-thousands of feet in the winter) to
hundreds of degrees (radiant heating from exhaust
components). In the "big airplane factories" we've
had suppliers of spiral wrap, split loom and zippered
sleeve wire bundling products come and go. The
added cost, labor, maintenance and addition to weight
have never passed muster with the guys who tracked
cost-of-ownership for airplanes.
You can bet that should this technology be considered
worthy of flight in a TC aircraft, it would be made
from materials similar to the wire it protects . . . i.e.
Tefzel or one of the more exotic synthetics. Given
that Tefzel tie wraps are around $1.50 each in low
quantities, you can bet that the cost of Tefzel spiral
wrap is similarly breathtaking.
>As an aside I did some informal tests of the black split loom and it burns
>and is not self extinguishing.
>Are thre any good fire resistant alternatives?
Not aware of any. The popular nylons are probably
incapable of tolerating the localized heating situation
you've identified. You might consider re-routing the
bundle, running it through fire-sleeve, or some other
process that puts a barrier between your wire bundle
and the IR heat source that's pushing it over the
cliff. I'd vote for re-routing the wire bundle.
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: | Split loom melting |
Bob,
Am I drawing the correct conclusion from your comments that using split loom
or most any "conduit" is NOT a preferred method of "protecting" a wire
bundle in the engine compartment?
I must admit that in my planning and building I have "assumed" conduit was
desirable from an appearance standpoint while not considering the
temperature the wires would be exposed to.
Allen Fulmer
RV7 Eggenfellner Subaru E6Ti
>>>-----Original Message-----
>>>From: owner-aeroelectric-list-server@matronics.com
>>>[mailto:owner-aeroelectric-list-server@matronics.com]On
>>>Behalf Of Robert L. Nuckolls, III
>>>Sent: Sunday, October 05, 2008 9:52 AM
>>>To: aeroelectric-list@matronics.com
>>>Subject: Re: AeroElectric-List: Split loom melting
>>>
>>>
>>>Nuckolls, III" <nuckolls.bob@cox.net>
>>>
>>>At 09:07 AM 10/5/2008 -0400, you wrote:
>>>>Caldwell" <lrsecaldwell@earthlink.net>
>>>>
>>>>I have experanced melting of some of the black split loom I used an
>>>>conduit to prevent wire chaffing in my engine compartment.
>>> One piese
>>>>that melted was 6 or 7 inches from the exhaust tube.
>>>>
>>>>Note that this is a recent problem that has occured after I
>>>add some
>>>>additional heat shield due to heat discoloration on the
>>>inside of the
>>>>lower cowl,
>>>>
>>>>Has anyone else had this problem?
>>>>
>>>>Does anyone have any data on what temperatue exists in the
>>>engine compartment?
>>>
>>> Temperatures under the cowl can range from ambient
>>> (OAT at xx-thousands of feet in the winter) to
>>> hundreds of degrees (radiant heating from exhaust
>>> components). In the "big airplane factories" we've
>>> had suppliers of spiral wrap, split loom and zippered
>>> sleeve wire bundling products come and go. The
>>> added cost, labor, maintenance and addition to weight
>>> have never passed muster with the guys who tracked
>>> cost-of-ownership for airplanes.
>>>
>>> You can bet that should this technology be considered
>>> worthy of flight in a TC aircraft, it would be made
>>> from materials similar to the wire it protects . . . i.e.
>>> Tefzel or one of the more exotic synthetics. Given
>>> that Tefzel tie wraps are around $1.50 each in low
>>> quantities, you can bet that the cost of Tefzel spiral
>>> wrap is similarly breathtaking.
>>>
>>>>As an aside I did some informal tests of the black split
>>>loom and it burns
>>>>and is not self extinguishing.
>>>>Are thre any good fire resistant alternatives?
>>>
>>> Not aware of any. The popular nylons are probably
>>> incapable of tolerating the localized heating situation
>>> you've identified. You might consider re-routing the
>>> bundle, running it through fire-sleeve, or some other
>>> process that puts a barrier between your wire bundle
>>> and the IR heat source that's pushing it over the
>>> cliff. I'd vote for re-routing the wire bundle.
>>>
>>>
>>> Bob . . .
>>>
>>>
>>> ----------------------------------------)
>>> ( . . . a long habit of not thinking )
>>> ( a thing wrong, gives it a superficial )
>>> ( appearance of being right . . . )
>>> ( )
>>> ( -Thomas Paine 1776- )
>>> ----------------------------------------
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>Checked by AVG - http://www.avg.com
>>>Date: 10/5/2008 9:20 AM
>>>
Message 4
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| Subject: | Unhappy Instrumentation on Jabiru 3300 |
(Long description- delete now if uninterested!)
The folks that build Light Sport Jabirus at my home field at Shelbyville TN
recently asked me to look at an annoying problem which appears on certain of
their completed composite airplanes using the Jabiru 3300 six-cylinder and
Grand Rapids EIS engine monitors tied to GRT Sport EFIS displays. These engines
have permanent-magnet alternators built into their flywheels and a very basic
solid-state rectifier/regulator that comes with the kits from Australia.
Except for this one problem, the basic electrical system, although not
designed to Aeroelectic principals, appears to work fine in the 100+ airplanes
they have produced using it, and it only appears on perhaps one out of three
aircraft completed in the past 6 months or so. The most excellent folks at
Grand Rapids have no solution, saying they are not seeing this on other
installations of their EIS. Units have been returned to them for testing with
no
anomalies found.
Problem: The EIS engine monitors are annunciating random "phantom" alarm
messages, indicating a monitored parameter has exceeded a set limit. These
include high or low EGT&CHT alarms, voltage levels, pressure levels etc. Of
particular interest is that on the EFIS engine monitor page there is a graphic
representation of CHT/EGT readings on a time scale (similar to a seismograph
trace). This shows a trace history of these temps as continuous lines
advancing across the screen. On the trace lines of the EGTs in particular there
are
obvious spikes (plus and minus). The duration of each spike is virtually
instantaneous and indicate an increase or decrease in EGT of from 50-200
degrees, assuming they were accurate. The spike frequency is random, sometimes
occurring 10-15 seconds apart, often much closer- frequency appears to be
highest after engine start, and less frequent as the battery recharges. These
spikes appear to be systemic as the alarms being generated are not limited to
EGT/CHT (the only data shown as traces) as noted above.
At first is seemed to be caused by the Right magneto, as grounding it
eliminates the spikes, but many attempts at relocating the P-leads and even
disconnecting them entirely made no improvement. P-leads are 18 gauge shielded,
single conductor using the shields to complete the circuit to a L/R/Start type
keyswitch. Any electrical wiring or components near the mag were relocated
with no improvement. Suppressor wires and plugs were tried with no change.
Replacing the mag also did nothing.
Suspecting the rather basic rectifier/regulator, I checked the Z-figures and
notes relating to the Jabiru and experimented with a 30,000uF 30VDC
electrolytic capacitor between the regulator output and ground. This clipped
the
tops of the highest of the spikes shown on the EGT traces, but had little other
effect. Another experiment was to disconnect the alternator output leads
from the regulator and run strictly on the battery, but the spikes persisted.
(All connections to the regulator are butt-spliced, soldered & shrink-wrapped)
This leads me to believe it has nothing to do with the charging system and
is specific to the Right magneto.
I've run out of ideas- all suggestions welcome!
I'd still like to experiment with a better rectifier/regulator, but unsure
where to hunt one down- perhaps others have found reliable substitutions? (The
B&C PRM1C-14 is limited to 14 amps continuous- 30-35 is required)
Mark Phillips
Columbia, TN
do not archive dragons prior to slaying!
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Message 5
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| Subject: | Split loom melting |
At 03:16 PM 10/5/2008 -0500, you wrote:
>
>Bob,
>
>Am I drawing the correct conclusion from your comments that using split loom
>or most any "conduit" is NOT a preferred method of "protecting" a wire
>bundle in the engine compartment?
Don't know how to define "preferred". If you look under
the cowl of a TC aircraft,
http://aeroelectric.com/Pictures/Wiring_Technique/A36_Firewall_B.jpg
http://aeroelectric.com/Pictures/Wiring_Technique/A36_Firewall_A.jpg
You can see that the designers use the UV/ozone resistant Tie-Straps
and MS21919 clamps. No other protection is considered necessary.
>I must admit that in my planning and building I have "assumed" conduit was
>desirable from an appearance standpoint while not considering the
>temperature the wires would be exposed to.
Tefzel wire is good to 150C . . . I'd take the low
temperature plastic stuff clear out of the engine
compartment. Then keep and eye on the bundle adjacent
to the observed damage . . . just to be sure you're
not bumping the Tefzel limits.
Bob . . .
Message 6
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| Subject: | Re: [GRT_EFIS] Unhappy Instrumentation on Jabiru 3300 |
An approach for thinking about it ...
Your problem is probably a result of one or more of the following.
1. Power spikes (supply or regulation problem)
2. Intermittent ground (internal to the units or in the wiring)
3. Faulty units (test by swapping known bad and known good
4. Spurious EXTERNAL input (mag ... as in BAD or as in poor wiring)
REMOVE the PM. See if the problem persists. If it foes away, consider the
20A alternator with more traditional regulator.
If THAT approach fails, sounds like the proverbial intermittent ground. Have
you swapped units between two planes to see if the problem follows the
unit???
If the "good" plane stays "good" with the "bad" unit, then clearly it is NOT
the unit (EIS).
How many amps can the total system deliver? How many are used? Does the
voltage ever go LOW or HIGH (can you monitor that?)?
Does it happen on ALL probes (as in a system wide measurement chance in all
places?)?
(If so, then probably not the probes or any of their connections. Something
COMMON to them all.)
Just random thoughts to ponder.
Contact me direct and we can chat.
James
(RV6, Columbia SC)
On Sun, Oct 5, 2008 at 6:13 PM, <fiveonepw@aol.com> wrote:
> (Long description- delete now if uninterested!)
>
> The folks that build Light Sport Jabirus at my home field at Shelbyville TN
> recently asked me to look at an annoying problem which appears on certain of
> their completed composite airplanes using the Jabiru 3300 six-cylinder and
> Grand Rapids EIS engine monitors tied to GRT Sport EFIS displays. These
> engines have permanent-magnet alternators built into their flywheels and a
> very basic solid-state rectifier/regulator that comes with the kits from
> Australia.
>
> Except for this one problem, the basic electrical system, although not
> designed to Aeroelectic principals, appears to work fine in the 100+
> airplanes they have produced using it, and it only appears on perhaps one
> out of three aircraft completed in the past 6 months or so. The most
> excellent folks at Grand Rapids have no solution, saying they are not seeing
> this on other installations of their EIS. Units have been returned to them
> for testing with no anomalies found.
>
> Problem: The EIS engine monitors are annunciating random "phantom" alarm
> messages, indicating a monitored parameter has exceeded a set limit. These
> include high or low EGT&CHT alarms, voltage levels, pressure levels etc. Of
> particular interest is that on the EFIS engine monitor page there is a
> graphic representation of CHT/EGT readings on a time scale (similar to a
> seismograph trace). This shows a trace history of these temps as continuous
> lines advancing across the screen. On the trace lines of the EGTs in
> particular there are obvious spikes (plus and minus). The duration of each
> spike is virtually instantaneous and indicate an increase or decrease in EGT
> of from 50-200 degrees, assuming they were accurate. The spike frequency is
> random, sometimes occurring 10-15 seconds apart, often much closer-
> frequency appears to be highest after engine start, and less frequent as the
> battery recharges. These spikes appear to be systemic as the alarms being
> generated are not limited to EGT/CHT (the only data shown as traces) as
> noted above.
>
> At first is seemed to be caused by the Right magneto, as grounding it
> eliminates the spikes, but many attempts at relocating the P-leads and even
> disconnecting them entirely made no improvement. P-leads are 18 gauge
> shielded, single conductor using the shields to complete the circuit to a
> L/R/Start type keyswitch. Any electrical wiring or components near the mag
> were relocated with no improvement. Suppressor wires and plugs were tried
> with no change. Replacing the mag also did nothing.
>
> Suspecting the rather basic rectifier/regulator, I checked the Z-figures
> and notes relating to the Jabiru and experimented with a 30,000uF 30VDC
> electrolytic capacitor between the regulator output and ground. This
> clipped the tops of the highest of the spikes shown on the EGT traces, but
> had little other effect. Another experiment was to disconnect the
> alternator output leads from the regulator and run strictly on the battery,
> but the spikes persisted. (All connections to the regulator are
> butt-spliced, soldered & shrink-wrapped) This leads me to believe it has
> nothing to do with the charging system and is specific to the Right magneto.
>
> I've run out of ideas- all suggestions welcome!
>
> I'd still like to experiment with a better rectifier/regulator, but
> unsure where to hunt one down- perhaps others have found reliable
> substitutions? (The B&C PRM1C-14 is limited to 14 amps continuous- 30-35 is
> required)
>
> Mark Phillips
> Columbia, TN
> do not archive dragons prior to slaying!
>
>
> ------------------------------
> New *MapQuest Local* shows what's happening at your destination. Dining,
> Movies, Events, News more. Try it out<http://local.mapquest.com/?ncid=emlcntnew00000001>
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Message 7
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| Subject: | EIS interference |
Problem: The EIS engine monitors are annunciating random "phantom" alarm
messages, indicating a monitored parameter has exceeded a set limit. These
include high or low EGT&CHT alarms, voltage levels, pressure levels
etc. Of particular interest is that on the EFIS engine monitor page there
is a graphic representation of CHT/EGT readings on a time scale (similar to
a seismograph trace). This shows a trace history of these temps as
continuous lines advancing across the screen. On the trace lines of the
EGTs in particular there are obvious spikes (plus and minus). The duration
of each spike is virtually instantaneous and indicate an increase or
decrease in EGT of from 50-200 degrees, assuming they were accurate. The
spike frequency is random, sometimes occurring 10-15 seconds apart, often
much closer- frequency appears to be highest after engine start, and less
frequent as the battery recharges. These spikes appear to be systemic as
the alarms being generated are not limited to EGT/CHT (the only data shown
as traces) as noted above.
Since these are strong anomalies in perceived data, one should
not discount the probability that the noise is coming in through
the temperature sensor leads (thermocouples I presume) that
may or may not electrically float at the engine end. The idea
T/C installation does NOT make electrical contact with the surface
being measured so that signal ground occurs at the instrument and
is not duplicated at the crankcase.
At first is seemed to be caused by the Right magneto, as grounding it
eliminates the spikes, but many attempts at relocating the P-leads and even
disconnecting them entirely made no improvement. P-leads are 18 gauge
shielded, single conductor using the shields to complete the circuit to a
L/R/Start type keyswitch. Any electrical wiring or components near the mag
were relocated with no improvement. Suppressor wires and plugs were tried
with no change. Replacing the mag also did nothing.
Bad mags don't cause this . . . Try running the system with all
P-leads disconnected at the engine. Kill the engine with fuel cutoff.
Totally eliminate p-lead wiring as part of the propagation
pathway.
Suspecting the rather basic rectifier/regulator, I checked the Z-figures
and notes relating to the Jabiru and experimented with a 30,000uF 30VDC
electrolytic capacitor between the regulator output and ground. This
clipped the tops of the highest of the spikes shown on the EGT traces, but
had little other effect. Another experiment was to disconnect the
alternator output leads from the regulator and run strictly on the battery,
but the spikes persisted. (All connections to the regulator are
butt-spliced, soldered & shrink-wrapped) This leads me to believe it has
nothing to do with the charging system and is specific to the Right magneto.
Unlikely that the alternator/rectifier/regulator is a culprit here
too. There are no events that occur in normal or abnormal operation
of the power generation at 10-15 second intervals.
I've run out of ideas- all suggestions welcome!
I'd still like to experiment with a better rectifier/regulator, but unsure
where to hunt one down- perhaps others have found reliable substitutions?
(The B&C PRM1C-14 is limited to 14 amps continuous- 30-35 is required)
If you've run the system with the alternator OFF and the
problem persists, then it's not a problem with either the
alternator or the rectifier/regulator. Have you tried running
the EIS system from a dedicated set of dry cells? A power source
separate from the ship's bus.
Does the airplane have a single point firewall ground? What
is the airplane's structure?
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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| Subject: | Re: EIS interference |
In a message dated 10/5/2008 8:40:14 P.M. Central Daylight Time,
nuckolls.bob@cox.net writes:
Since these are strong anomalies in perceived data, one should
not discount the probability that the noise is coming in through
the temperature sensor leads (thermocouples I presume) that
may or may not electrically float at the engine end. The idea
T/C installation does NOT make electrical contact with the surface
being measured so that signal ground occurs at the instrument and
is not duplicated at the crankcase.
>>>>>
Understand. CHT thermocouples used are TC wires crimped to ring terminals
under spark plugs (supplied by GRT) and obviously grounded at head- EGTs are
standard GRT probes inserted into exhaust pipes held in place by hose clamps.
Experiment would be removing all CHT probes to eliminate grounding at head?
This might pinpoint the antagonist, but without dedicated wells for
bayonet-type probes, how to monitor CHTs?
Bad mags don't cause this . . . Try running the system with all
P-leads disconnected at the engine. Kill the engine with fuel cutoff.
Totally eliminate p-lead wiring as part of the propagation
pathway.
>>>>
Disconnecting Right mag had no effect- will try both...
Unlikely that the alternator/rectifier/regulator is a culprit here
too. There are no events that occur in normal or abnormal operation
of the power generation at 10-15 second intervals.
>>>>>
My tentative conclusion as well, but just checking!
If you've run the system with the alternator OFF and the
problem persists, then it's not a problem with either the
alternator or the rectifier/regulator. Have you tried running
the EIS system from a dedicated set of dry cells? A power source
separate from the ship's bus.
>>>>>
This was next on the experiment list, but if isolated power to instrument
eliminates problem, doesn't that point back to a problem with power supplied to
the EIS with a finger aimed at the alternator/regulator system? Any problem
powering EIS from a separate PC-625 VLSA batt instead of the dry cells?
Does the airplane have a single point firewall ground? What
is the airplane's structure?
>>>>
They properly employ forest-of-tabs from B&C. Composite structure,
stainless firewall over plywood bonded to structure.
Appreciate the reply Bob- will report on experiments...
Mark
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| Subject: | Re: EIS interference |
At 10:13 PM 10/5/2008 -0400, you wrote:
>In a message dated 10/5/2008 8:40:14 P.M. Central Daylight Time,
>nuckolls.bob@cox.net writes:
>
> Since these are strong anomalies in perceived data, one should
> not discount the probability that the noise is coming in through
> the temperature sensor leads (thermocouples I presume) that
> may or may not electrically float at the engine end. The idea
> T/C installation does NOT make electrical contact with the surface
> being measured so that signal ground occurs at the instrument and
> is not duplicated at the crankcase.
> >>>>>
>Understand. CHT thermocouples used are TC wires crimped to ring terminals
>under spark plugs (supplied by GRT) and obviously grounded at head- EGTs
>are standard GRT probes inserted into exhaust pipes held in place by hose
>clamps. Experiment would be removing all CHT probes to eliminate
>grounding at head? This might pinpoint the antagonist, but without
>dedicated wells for bayonet-type probes, how to monitor CHTs?
>
Okay, I'm betting that the T/C signal for each
input goes to a AD595 or similar thermocouple
conditioning chip. These are high gain op amps
with limited common mode. When you ground the t/c
at the engine end, you MUST keep the signal ground
for the instrument tightly bonded to the crankcase
too. If you have too small, too shared, too long
of wires in ground system, common mode noises from
about anywhere in the system can get into those
microvolt-sensitive inputs to the TC conditioners.
> >>>>>
>This was next on the experiment list, but if isolated power to instrument
>eliminates problem, doesn't that point back to a problem with power
>supplied to the EIS with a finger aimed at the alternator/regulator
>system? Any problem powering EIS from a separate PC-625 VLSA batt instead
>of the dry cells?
any source of 12v will do. But only tells you what the
propagation path is . . . not the antagonist. Sub
the 12 supply (+) first. Don't mess with grounds.
If the noise is still there, then move the EIS ground
directly to the crankcase and see what happens.
> Does the airplane have a single point firewall ground? What
> is the airplane's structure?
> >>>>
>They properly employ forest-of-tabs from B&C. Composite structure,
>stainless firewall over plywood bonded to structure.
Okay, make sure that the EIS instrument power ground
gets it's own dedicated wire to the forest of tabs.
Check that the bond strap from crankcase to forest
of tabs is suited to task. 4AWG wire or bigger.
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