Today's Message Index:
----------------------
1. 02:32 AM - Re: EXP 2 Bus workaround - Master Solenoid Failure (BobsV35B@aol.com)
2. 07:19 AM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Ken)
3. 07:30 AM - Re: Battery contactor failure (Jeff Luckey)
4. 07:39 AM - Re: Re: EXP 2 Bus workaround (Sacha)
5. 07:54 AM - Re: EXP 2 Bus workaround - Master Solenoid Failure (BobsV35B@aol.com)
6. 08:07 AM - Re: Re: EXP 2 Bus workaround (Jeff Luckey)
7. 08:14 AM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
8. 08:30 AM - Accident library addition (Robert L. Nuckolls, III)
9. 08:53 AM - Contactors (Eric M. Jones)
10. 08:58 AM - Re: EXP 2 Bus workaround (user9253)
11. 09:54 AM - Re: EXP 2 Bus workaround (user9253)
12. 11:06 AM - Re: Re: EXP 2 Bus workaround (Sacha)
13. 11:06 AM - Re: Re: EXP 2 Bus workaround (Sacha)
14. 11:14 AM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
15. 11:23 AM - Re: Re: hypothetical question (Rob Housman)
16. 11:37 AM - Re: Re: EXP 2 Bus workaround (Bob McCallum)
17. 01:37 PM - Re: Alternator without a Battery (Sacha)
Message 1
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Subject: | Re: EXP 2 Bus workaround - Master Solenoid Failure |
Good Morning All,
I have not followed all of this thread, but agree that not all engines
windmill like our friendly Continentals and Lycomings. I have about twenty
hours flying a Legend Cub powered by the Jabiru engine. It is a nice smooth
running engine, but if it runs out of fuel or the mags are shut off, the prop
stops!
Happy Skies,
Old Bob
In a message dated 10/27/2013 3:32:26 A.M. Central Daylight Time,
jluckey@pacbell.net writes:
I believe that some of the installations of the Rotax 912 (and probably
other power systems) do not windmill (but the 912 may not be
electrically-dependent ).
However, I don't think you can categorically say that ALL engines will
windmill. In addition some flight conditions may cause a windmilling prop to
stop. A possible scenario: The pilot becomes task saturated on the
electrical failure and lets the airspeed bleed down and the prop stops.
Dooh! I forgot about the alternator - BUT - I've never trusted an
alternator that was not connected to a battery, therefore I would be reluctant
to
have that as a fall back.
What about moving the starter feed to the battery side of the master?
-Jeff
Message 2
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Subject: | Re: EXP 2 Bus workaround - Master Solenoid Failure |
Old Bob
Just curious whether you've tried it and whether it was the 4, 6, or 8
cylinder jab? (You probably have tried it or talked to someone who has
if you posted it.)
There were lots of opinions that my geared setup would not windmill but
it most certainly does. More opinions than facts as is often the case on
the internet. For sure there are some known engines/reduction units that
do not windmill.
(break)
I like the concept of minimal connections and components in the truly
essential engine circuits so I like feeding them directly from battery
busses. Engine stoppage occurs far more often than the need to kill
every last electric circuit in a dire emergency. (I'm sure that a
significant percentage of engine out landings/crashes occur with the
battery master still on anyway). I favor feeding "keep it running"
engine circuits directly from battery busses. Sure, route backups
through the master if one wishes but not primary circuits. Then
regardless of windmilling, I see little need to wire such that an engine
can be cranked with the master off or with a failed battery contactor.
That caters to multiple failures and raises other safety concerns IMO.
Ken
On 27/10/2013 5:31 AM, BobsV35B@aol.com wrote:
> Good Morning All,
> I have not followed all of this thread, but agree that not all engines
> windmill like our friendly Continentals and Lycomings. I have about
> twenty hours flying a Legend Cub powered by the Jabiru engine. It is a
> nice smooth running engine, but if it runs out of fuel or the mags are
> shut off, the prop stops!
> Happy Skies,
> Old Bob
> In a message dated 10/27/2013 3:32:26 A.M. Central Daylight Time,
> jluckey@pacbell.net writes:
>
>
> I believe that some of the installations of the Rotax 912 (and
> probably other power systems) do not windmill (but the 912 may not
> be electrically-dependent ).
>
> However, I don't think you can categorically say that ALL engines
> will windmill. In addition some flight conditions may cause a
> windmilling prop to stop. A possible scenario: The pilot becomes
> task saturated on the electrical failure and lets the airspeed bleed
> down and the prop stops.
>
> Dooh! I forgot about the alternator - BUT - I've never trusted an
> alternator that was not connected to a battery, therefore I would be
> reluctant to have that as a fall back.
>
> What about moving the starter feed to the battery side of the master?
>
> -Jeff
>
>
Message 3
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Subject: | Re: Battery contactor failure |
=0A=0AMy comment is italics=0A=0A=0A-Jeff=0A=0A=0A_________________________
_______=0A From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
=0ATo: aeroelectric-list@matronics.com =0ASent: Saturday, October 26, 2013
9:32 PM=0ASubject: AeroElectric-List: Battery contactor failure=0A =0A=0A--
bob@aeroelectric.com>=0A=0AAt 12:00 AM 10/27/2013, you wrote:=0A=0A> I beli
eve that some of the installations of the Rotax 912 (and probably other pow
er systems) do not windmill (but the 912 may not be electrically-dependent
).=0A=0AOnly if the fuel is delivered by engine driven pump=0Aor gravity. T
he ignition is electronic driven directly=0Afrom magnets on the starter rin
g gear.=0A=0A> However, I don't think you can categorically say that ALL en
gines will windmill.- In addition some flight conditions may cause a wind
milling prop to stop.- A possible scenario: The pilot becomes task satura
ted on the electrical failure and lets the airspeed bleed down and the prop
stops.=0A=0AThat's s double failure again. Failure tolerant systems=0Awith
a plan-b do not saturate pilots.=0A=0ADisagree - There is way too much cas
e history of pilots becoming distracted, over seemingly trivial issues, to
suggest that you can write-off this scenario.=0A=0A> Dooh! I forgot about t
he alternator - BUT - I've never trusted an alternator that was not connect
ed to a battery, therefore I would be reluctant to have that as a fall back
.=0A=0A- Because you know them to be unreliable or simply=0A- don't kno
w. Actually, Cessna and others who opted=0A- for the split rocker switch
were probably in violation=0A- of legacy design goals.=0A=0AOnce upon a t
ime waaay back in the late 70s I had seen a few alternators lose voltage re
gulation when battery became disconnected.- This was in the marine enviro
nment.- Regulators are most certainly better now but those experiences ha
ve stuck with me.=0A=0A- Until that time, airplanes flew nicely on either
=0A- battery, generator or both. When the alternator=0A- came along, th
e airframe guys elected to put=0A- alternators on even tho they were not
plug-n-play=0A- for the failure tolerance offered by generators.=0A=0A-
The Bonanza and Barons continued to offer alternator-=0A- only operation
s but if I recall correctly, the Liberal=0A- airplanes had split rockers.
=0A=0A- PM alternators are easy to get on-line without a=0A- battery an
d it may well be that belt-driven alternators=0A- on a Lycoming are too.
They run very fast. I need to=0A- get some time on B&C's test bench and r
un some experiments.=0A=0A> What about moving the starter feed to the batte
ry side of the master?=0A=0A- If you're willing to have an always hot fee
der to a=0A- starter contactor . . .=0A=0AAre there reasons to not do thi
s?Is that any worse than having an always hot feed to the "main" bus?=0A-
==
Message 4
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Subject: | Re: EXP 2 Bus workaround |
> If you're willing to have an always hot feeder to a
> starter contactor . . .
That doesn't sound very safe when you're on he ground. Keys are out, master e
tc off, someone is by the prop and someone else accidentally actuates the st
arter by pushing the starter button or whatever. Even if the engine doesn't s
tart you can still do some damage.
Message 5
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Subject: | Re: EXP 2 Bus workaround - Master Solenoid Failure |
Good Morning Ken
You wrote:
"Just curious whether you've tried it and whether it was the 4, 6, or 8
cylinder jab? (You probably have tried it or talked to someone who has
if you posted it.)"
I flew the airplane over twenty hours in less than a week flying off a lot
of the required time for an experimental category airplane. It was at the
factory in Texas, so I did have the factory folks to help with any
difficulties encountered.
The runways were long and the traffic was nil so I had no hesitation to do
things that would cause the engine to quit. I never had to make a "forced"
landing as the starter always worked, but I did shut off the fuel at least
once just to check how well it would restart. Same for shutting off the
ignition. It also quit at low speeds if the idle RPM was set on the low side.
To get a nice short Cub style three point landing, the idle RPM had to be
so low that the engine would quit and the prop would stop turning well
before touchdown. I do not recall the exact airspeed at which the prop would
stop, but it was not much below sixty mph. It has been over five years since I
did that test flying.
That was the only feature of the Jabiru install that I really did not care
for. If it were up to me, I would have used the O-200 Continental or an O-
320 Lycoming.
The high idle made for longer than necessary ground roll out and/or
excessive use of the brakes.
It is a 6 cylinder 3300 Jabiru with the BMW carburetor.
Happy Skies,
Old Bob
Message 6
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Subject: | Re: EXP 2 Bus workaround |
=0A=0A=0A=0A________________________________=0A From: Sacha <uuccio@gmail.c
om>=0ATo: "aeroelectric-list@matronics.com" <aeroelectric-list@matronics.co
m> =0ASent: Sunday, October 27, 2013 6:24 AM=0ASubject: Re: AeroElectric-Li
st: Re: EXP 2 Bus workaround=0A =0A=0A=0A-If you're willing to have an al
ways hot feeder to a=0A>-starter contactor . . .=0A=0AThat doesn't sound
very safe when you're on he ground. Keys are out, master etc off, someone i
s by the prop and someone else accidentally actuates the starter by pushing
the starter button or whatever. Even if the engine doesn't start you can s
till do some damage. =0A=0AThat is not the case, with the master off you wi
ll not be able to crank as the coil circuit for starter contactor will not
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Message 7
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Subject: | Re: EXP 2 Bus workaround |
>That doesn't sound very safe when you're on he ground. Keys are out,
>master etc off, someone is by the prop and someone else accidentally
>actuates the starter by pushing the starter button or whatever. Even
>if the engine doesn't start you can still do some damage.
There are TWO inputs to a starter contactor.
FAT wire power to operate the motor and
small wire power through the starter switch
to energize the contactor coil. One COULD
consider an always hot FAT wire that bypasses
the battery contactor while shutting down
the power source for the starter push-button.
But this is contrary to legacy design goals
for achieving max-dark on an electrical system
when all switches are OFF.
Bob . . .
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Subject: | Accident library addition |
I was made aware of this incident involving a LA235 that
appeared to have suffered electrical system difficulties.
http://tinyurl.com/mwo3f4x
The NTSB said 'everything was working but the
battery was dead.' This engine seems to have
run out of fuel because transfer pumps were
deprived of power to bring fuel to a header
tank.
The documents are markedly devoid of a finding for
root cause. The narrative paints and image of an
owner/pilot who hasn't got a clue for the significance
of "anomalies" in system operation. The airplane
had been begging for help for perhaps two months
before the accident. His notion of making the
airplane flightworthy was to install a freshly
charged battery . . . that failed minutes after
takeoff.
His header tank must have been nearly dry at
takeoff which begs the question as to his use
of a checklist for verification if header tank
fuel and functionality of the transfer pumps
were working and the altrrnator was charging
the battery.
As near as we can tell, nothing was broken. No
parts had failed to do their intended task except
that a working alternator failed to charge a battery.
This accident has more to teach about the technical
skills and operational philosophy of the owner/operator
than about the design of an electrical system.
Bob . . .
Message 9
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The requirement for a main battery contactor comes from the FAA's requirement to
have the main battery disconnected "by one hand" in the event of a forced landing.
Cutting off the main source of electrical energy should reduce the chance
of ignition one supposes.
NASCAR and various racing groups have the same problem but they usually have decided
that a contactor failure is to be avoided by the elimination of electrical
coil-type contactors, instead choosing rugged mechanical switches like "Flaming
River Battery Switches".
So keep in mind:
1) A contactor won't fail if you don't have one.
2) A contactor by regulations only has to open, not close. Sort of like a parachute.
3) Really big switches can be used instead of small switches and contactors. My
Grandfather's Chevy had a starter footswitch. Still seems like a good idea.
--------
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=411531#411531
Message 10
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Subject: | Re: EXP 2 Bus workaround |
I figured out the reason for D3 in the EXP2Bus (questioned in a previous post).
When the master switch is open, D3 prevents current from flowing in series through
the master contactor coil and into the EXP2Bus.
I drew a new schematic (pdf attached) using the EXP2Bus and also a separate Engine
Bus. I also have a dwg version if anyone is interested.
The Engine bus is fed from two paths so that any one failure will not cut power
to the engine. The EXP2Bus also has outputs that can supply engine loads.
An endurance bus is not needed because the SkyView and GPS both have internal
backup batteries. The COM radio is powered by either the EXP2Bus or by the ENG
bus through dual diodes inside of the EXP2Bus (CLRNC DEL input).
Comments and suggestions welcome.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411532#411532
Attachments:
http://forums.matronics.com//files/exp2_and_eng_bus_548.pdf
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Subject: | Re: EXP 2 Bus workaround |
Bob,
What are your thoughts on having a separate switch for the alternator field versus
using the second half of a double pole master switch?
I know that your designs use a progressive transfer switch with the center position
battery only with the alternator off. But I am thinking about the EXP2Bus
(or any electrical system) that does not have the progressive transfer switch,
just a common DPDT switch. Assuming the pilot has a plan B, for instance
an E-Bus, she could shut off the one DPDT Master-Alt switch in the event of an
alternator failure. Most likely the pilot will want the master off anyway to
conserve the battery.
Or is it better to have a separate Alt switch?
Thanks, Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411535#411535
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Subject: | Re: EXP 2 Bus workaround |
>>> If you're willing to have an always hot feeder to a
>>> starter contactor . . .
>>
>> That doesn't sound very safe when you're on he ground. Keys are out, mast
er etc off, someone is by the prop and someone else accidentally actuates th
e starter by pushing the starter button or whatever. Even if the engine does
n't start you can still do some damage.
>>
>> That is not the case, with the master off you will not be able to crank a
s the coil circuit for starter contactor will not be powered. See dwg.
You're correct, sorry I spoke before i took a look at the actual circuit.
Sacha
Ps. What is the issue with wether the prop windmills or stops? Is it that t
he engine is easier to restart if the prop is windmilling?
Message 13
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Subject: | Re: EXP 2 Bus workaround |
>>> That doesn't sound very safe when you're on he ground. Keys are out, master
etc off, someone is by the prop and someone else accidentally actuates the starter
by pushing the starter button or whatever. Even if the engine doesn't start
you can still do some damage.
>>
>> There are TWO inputs to a starter contactor.
>> FAT wire power to operate the motor and
>> small wire power through the starter switch
>> to energize the contactor coil. One COULD
>> consider an always hot FAT wire that bypasses
>> the battery contactor while shutting down
>> the power source for the starter push-button.
>> But this is contrary to legacy design goals
>> for achieving max-dark on an electrical system
>> when all switches are OFF.
>>
Got it, thanks!
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Subject: | Re: EXP 2 Bus workaround |
At 11:53 AM 10/27/2013, you wrote:
>
>Bob,
>What are your thoughts on having a separate switch for the
>alternator field versus using the second half of a double pole master switch?
Depends on how well the alternator performs without
a battery. It would be nice to have it run independently
of the battery.
> I know that your designs use a progressive transfer switch with
> the center position battery only with the alternator off. But I am
> thinking about the EXP2Bus (or any electrical system) that does not
> have the progressive transfer switch, just a common DPDT
> switch. Assuming the pilot has a plan B, for instance an E-Bus,
> she could shut off the one DPDT Master-Alt switch in the event of
> an alternator failure. Most likely the pilot will want the master
> off anyway to conserve the battery.
The ideas behind the e-bus was to offer a means by
which everything not needed during en route flight,
i.e. cruising for an hour or more watching the ground
go by. This includes the battery contactor which
draws .8 to 1.0 amps by itself . . . as much as one
or two more radios.
> Or is it better to have a separate Alt switch?
It's nice to turn battery on leaving alternator
off for ground ops. A non-rotating alternator
draws about 3A of field current and gets hot.
When the system is fitted with crowbar ov protection,
then there's a circuit breaker that can be pulled to
disable the alternator for maintenance.
Some of my earlier drawings were dpdt bat/alt switch
+ circuit breaker. But there was such a love affair
going on over the split rocker switch that I decided
to describe a replacement for the same functionality
in a toggle switch.
Whether or not a separate switch is advised is predicated
on alternator performance sans battery.
Bob . . .
Message 15
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Subject: | Re: hypothetical question |
Are you suggesting that New York to Paris is not a long distance? Some
folks thought it was in 1927.
Do not archive
Best regards,
Rob Housman
Europa XS A070
Rotax 914
Airframe complete
Avionics a work in progress
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Eric M.
Jones
Sent: Wednesday, October 23, 2013 7:46 AM
Subject: AeroElectric-List: Re: hypothetical question
--> <emjones@charter.net>
Let's take a loop 4 meters in diameter and put 200A through it. The magnet
field created is about 0.63 Gauss. This is about the same as the Earth's
magnetic field itself. So I wouldn't be too worried about it.
It is telling that your friend was a Navy man. The US navy knows more about
the Earth's magnetic field than anyone else. Reading the published naval
papers on the subject is fascinating. They degauss ships hulls (Philadelphia
Experiment!), and even know how the pounding of rough seas changes the
magnetism of ships' hulls over time.
Aircraft steel tubes magnetize over time and compass compensation is
periodically figured in. But of course, the Earth's magnetic field and its
consistency is not great either. For local use this is okay. No pilot ever
used a compass for long distances.
--------
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=411199#411199
Message 16
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Subject: | Re: EXP 2 Bus workaround |
If the prop is windmilling then the starter isn't needed for a restart. All
you need is to provide fuel and spark, it already turning.
Bob McC
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Sacha
Sent: Sunday, October 27, 2013 2:05 PM
Subject: Re: AeroElectric-List: Re: EXP 2 Bus workaround
If you're willing to have an always hot feeder to a
starter contactor . . .
That doesn't sound very safe when you're on he ground. Keys are out, master
etc off, someone is by the prop and someone else accidentally actuates the
starter by pushing the starter button or whatever. Even if the engine
doesn't start you can still do some damage.
That is not the case, with the master off you will not be able to crank as
the coil circuit for starter contactor will not be powered. See dwg.
You're correct, sorry I spoke before i took a look at the actual circuit.
Sacha
Ps. What is the issue with wether the prop windmills or stops? Is it that
the engine is easier to restart if the prop is windmilling?
Message 17
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Subject: | Alternator without a Battery |
>From the Rotax Installation Manual, Section 24-00-00, page 7:
"A capacitor (see fig. 11, pos 14) of at least 22000 uF/25V is necessary to
protect the correct function of regulator and to flatten voltage. The
regulator is not designed to store any electrical charge. If for any reason
the battery or bus system is disconnected from the regulator while the
engine is running (i.e. the master switch is shut off) the capacitor will
safely absorb and dissipate the electrical charge produced by the generator.
Otherwise the regulator would be damaged."
Thanks Rick. I had missed your post.
sacha
Do not archive
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