Today's Message Index:
----------------------
1. 05:47 AM - Re: Z13-8 modification and LSE ignition wiring (Tailwind1)
2. 07:08 AM - Re: Re: Z13-8 modification and LSE ignition wiring (Charlie England)
3. 01:09 PM - Re: Re: Z13-8 modification and LSE ignition wiring (Robert L. Nuckolls, III)
4. 01:18 PM - Re: Re: Z13-8 modification and LSE ignition wiring (Robert L. Nuckolls, III)
5. 02:49 PM - Re: Re: Z13-8 modification and LSE ignition wiring (Charlie England)
6. 06:39 PM - Re: Re: Z13-8 modification and LSE ignition wiring (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Z13-8 modification and LSE ignition wiring |
user9253 wrote:
> Link to discussion of the SD8 self energizing circuit:
> http://www.matronics.com/forums/viewtopic.php?t=11971&view=previous&sid=8d09bfcf265444a653c4d15375aa3b74
> If you think that both the main alternator and the battery will fail on the same
flight, then yes,
> you need the self energizing feature for the SD8. It might seem complicated to
you, but you can do it.
> Klause Savior thinks that the battery is one of the most reliable things in
an airplane. It is more reliable than a pilot.
> Consider using diodes instead of a switch to choose between the battery bus or
E-bus. Diodes are more reliable than
> switches and diodes eliminate pilot error and pilot workload in this application.
> Batteries supply the ignition source for fires following off airport landings.
> The pilot should have the ability to shut off all electrical power as close to
the source as possible.
I am aware of the need to be able to shut off power near the source but cannot
think of a reliable way to do this with ignitions connected to a battery buss,
surely dont want to use a relay (for reliability) and the switches will be about
4 of wire away from the battery on the firewall, as to using diodes instead
of switches, one switch is certainly required to be able to shut off the ignition
so I was thinking of using one single pole on/off/on switch to be able to
select either power source, this allows power source selection without adding
another switch to the circuit. I see the benefit of diodes but they would also
be added to the switch in the circuit so would allow auto-switching but not
increase reliability...what am I missing?
Thanks
--------
Flying Sonerai II with A80 Continental. Wittman W10 Tailwind under construction,
O360, dual LSE electronic ignition, airframe complete and covered, engine hung,
cowl built. Working on electrical, instrumentation, and other details.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498505#498505
Message 2
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| Subject: | Re: Z13-8 modification and LSE ignition wiring |
On Wed, Sep 23, 2020 at 7:54 AM Tailwind1 <timmikus38@gmail.com> wrote:
m
> >
>
>
> user9253 wrote:
> > Link to discussion of the SD8 self energizing circuit:
> >
> http://www.matronics.com/forums/viewtopic.php?t=11971&view=previous&s
id=8d09bfcf265444a653c4d15375aa3b74
> > If you think that both the main alternator and the battery will fail on
> the same flight, then yes,
> > you need the self energizing feature for the SD8. It might seem
> complicated to you, but you can do it.
> > Klause Savior thinks that the battery is one of the most reliable
> things in an airplane. It is more reliable than a pilot.
> > Consider using diodes instead of a switch to choose between the battery
> bus or E-bus. Diodes are more reliable than
> > switches and diodes eliminate pilot error and pilot workload in this
> application.
> > Batteries supply the ignition source for fires following off airport
> landings.
> > The pilot should have the ability to shut off all electrical power as
> close to the source as possible.
>
>
> I am aware of the need to be able to shut off power near the source but
> cannot think of a reliable way to do this with ignitions connected to a
> battery buss, surely don=99t want to use a relay (for reliability)
and the
> switches will be about 4=99 of wire away from the battery on the fi
rewall, as
> to using diodes =9Cinstead=9D of switches, one switch is cert
ainly required to
> be able to shut off the ignition so I was thinking of using one single po
le
> on/off/on switch to be able to select either power source, this allows
> power source selection without adding another switch to the circuit. I se
e
> the benefit of diodes but they would also be added to the switch in the
> circuit so would allow auto-switching but not increase reliability...what
> am I missing?
>
> Thanks
>
>
> While you can buy very reliable switches, it's still likely to be the
least reliable component in the chain. From a pure FMEA standpoint, a
mechanical failure (and some electrical failures) in the switch will take
out both power sources to the ignition. Perhaps looking at the E in FMEA is
appropriate. The effect of losing one ignition, for whatever reason, is
slightly reduced fuel efficiency/power. It shouldn't put you on the ground.
That might simplify decision making (and devices).
To protect the wire itself, I like using fusible links. For light consumers
like the ignitions, a few inches of 22ga wire at the battery bus (sleeved
with a fiberglass jacket) soldered to 18ga wire feeding the switch/ignition
will protect the always-hot section of wire from catastrophic faults.
Charlie
Message 3
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| Subject: | Re: Z13-8 modification and LSE ignition wiring |
>
>I am aware of the need to be able to shut off
>power near the source but cannot think of a
>reliable way to do this with ignitions connected
>to a battery buss, surely don=99t want to use a
>relay (for reliability) and the switches will be
>about 4=99 of wire away from the battery on the
>firewall, as to using diodes =9Cinstead=9D of
>switches, one switch is certainly required to be
>able to shut off the ignition so I was thinking
>of using one single pole on/off/on switch to be
>able to select either power source, this allows
>power source selection without adding another
>switch to the circuit. I see the benefit of
>diodes but they would also be added to the
>switch in the circuit so would allow
>auto-switching but not increase reliability...what am I missing?
How big are the battery bus fuses? Taking the
system 'max cold' at the source is a crash
safety issue. The regs allow TC aircraft to
carry always hot feeders protected at no
more than 5A. Given that fuses are MANY
times faster than breakers, I'd comfortably
extend that feeder size to 7A.
Anything protected at that level or below
may enjoy long, un-switched feeders.
Why the 'auto switching'? The engine will
run on one ignition quite nicely. What
are the probabilities for dual failures
of single power paths? Assuming you've
detected an unacceptable probability,
then do you have steps in the pre-flight
check list to insure that all contingency
paths are functioning? In such cases,
it's better to design out the failure
condition than to add automatic features
that contribute their own burdens to
work load.
Bob . . .
Message 4
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| Subject: | Re: Z13-8 modification and LSE ignition wiring |
>
>To protect the wire itself, I like using fusible links. For light
>consumers like the ignitions, a few inches of 22ga wire at the
>battery bus (sleeved with a fiberglass jacket) soldered to 18ga wire
>feeding the switch/ignition will protect the always-hot section of
>wire from catastrophic faults.
but doesn't satisfy the crash safety condition
Fusible links are generally limited to use in
areas protected by battery master but included
to isolate hard-faulted feeders from the remainder
of normally functioning distribution.
The battery bus should (1) drive fuse or breaker
protected feeders at 7A or smaller -OR- if protection
is larger, then a relay at the bus to manage that
feeder's crash safety recommendations.
Bob . . .
Message 5
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| Subject: | Re: Z13-8 modification and LSE ignition wiring |
[image: image.png]
>From the Lightspeed installation manual. I was working toward improving on
the factory recommendation in this document. While a fusible link won't be
as fast as a fuse, it seems better than a 5 or 6 foot long always hot wire
to the CB.
Charlie
On Wed, Sep 23, 2020 at 3:26 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
>
> To protect the wire itself, I like using fusible links. For light
> consumers like the ignitions, a few inches of 22ga wire at the battery bus
> (sleeved with a fiberglass jacket) soldered to 18ga wire feeding the
> switch/ignition will protect the always-hot section of wire from
> catastrophic faults.
>
>
> but doesn't satisfy the crash safety condition
>
> Fusible links are generally limited to use in
> areas protected by battery master but included
> to isolate hard-faulted feeders from the remainder
> of normally functioning distribution.
>
> The battery bus should (1) drive fuse or breaker
> protected feeders at 7A or smaller -OR- if protection
> is larger, then a relay at the bus to manage that
> feeder's crash safety recommendations.
>
> Bob . . .
>
Message 6
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| Subject: | Re: Z13-8 modification and LSE ignition wiring |
From the Lightspeed installation manual. I was working toward
improving on the factory recommendation in this document. While a
fusible link won't be as fast as a fuse, it seems better than a 5 or
6 foot long always hot wire to the CB.
LSE ignitions were installed on the N811HB
accident aircraft and decidedly not wired with
due diligence to competent FMEA or best practices.
Nor were they wired to LSE instructions.
Kluse and I worked on that case and discussed his
power source recommendations (then 10 years
old or more). He didn't disagree with recommendations
and reasoning explained in the 'Connection but
wasn't interested in refining his instructions.
He cited a long successful field history.
Klause is an accomplished performance guy and
has an impressive record of marketing success.
But he is not a systems integrator. We've been
hashing over the Z-figures here on the List
for almost 30 years. I suggest they've
evolved in ways that makes the system more
robust while striving for simplicity of pilot
workload, elegant FMEA outcomes and lowest
cost of ownership while meeting design
goals.
I'm the first to admonish, "When in doubt follow
the manufacturer's instructions." The flip side
of that coin is, "If you've done the homework,
modifications that go to a more elegant configuration
at equal or less risk, go for it."
Elegant, low risk craftsmanship is what we strive
for here.
Bob . . .
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