Today's Message Index:
----------------------
1. 03:52 AM - Re: EXP 2 Bus workaround (Ken)
2. 05:51 AM - Re: Landing gear warning trigger (donjohnston)
3. 06:05 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
4. 06:50 AM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
5. 06:52 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
6. 06:58 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
7. 06:59 AM - Re: EXP 2 Bus workaround (John W Livingston)
8. 07:45 AM - Re: EXP 2 Bus workaround (Fred Klein)
9. 07:58 AM - Re: EXP 2 Bus workaround (Richard Girard)
10. 08:42 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
11. 08:46 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
12. 08:49 AM - Re: EXP 2 Bus workaround (Ken)
13. 08:54 AM - Re: EXP 2 Bus workaround (Fred Klein)
14. 08:58 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
15. 09:08 AM - Re: EXP 2 Bus workaround (Fred Klein)
16. 09:59 AM - Re: EXP 2 Bus workaround (Fred Klein)
17. 10:10 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
18. 10:30 AM - Re: EXP 2 Bus workaround (Fred Klein)
19. 10:57 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
20. 11:22 AM - Re: EXP 2 Bus workaround (Fred Klein)
21. 11:37 AM - Re: EXP 2 Bus workaround (Bob McCallum)
22. 12:26 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
23. 12:38 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
24. 12:51 PM - Re: EXP 2 Bus workaround (user9253)
25. 12:54 PM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
26. 01:21 PM - Re: EXP 2 Bus workaround (Bob McCallum)
27. 01:56 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
28. 02:10 PM - Re: EXP 2 Bus workaround (Fred Klein)
29. 02:16 PM - Re: EXP 2 Bus workaround (Fred Klein)
30. 02:20 PM - Re: EXP 2 Bus workaround (user9253)
31. 06:50 PM - EXP 2 Bus workaround - Master Solenoid Failure (Jeff Luckey)
32. 08:16 PM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Robert L. Nuckolls, III)
33. 08:25 PM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Robert L. Nuckolls, III)
34. 10:01 PM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Jeff Luckey)
35. 10:33 PM - Battery contactor failure (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: EXP 2 Bus workaround |
FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work
fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes up
no more than 2 psi. even with my somewhat restrictive 5/16" return
plumbing. Some fellows run both pumps for landing and takeoff. Selecting
both on is the first thing we do if the engine is not running properly.
Injector flow increases with the square root of pressure so that is not
an issue since normal EFI pressures run around 38 psi above manifold
pressure.
Ken
On 25/10/2013 10:42 PM, Robert L. Nuckolls, III wrote:
> *
> *
>> Let's talk about the 2 fuel pumps for a MPEFI engine. Unlike w/ carb
>> engines, the 2nd pump is not used as a boost pump. I'm advised that w/
>> a MPEFI engine, one never wants to run more than ONE pump at a time
>> due to excessive pressure in the system.
>
> * How does this happen? I understand that there's a pressure
> regulator downstream of the pump outputs. Paralleling two
> active pumps only increases potential for flow . . . like
> hooking two batteries in parallel.*
Message 2
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| Subject: | Re: Landing gear warning trigger |
> Yep. You already have a fabricated bracket and two anchor bolts available
> close by. I'd just re-make the existing bracket (or add a new one) to
> extend toward the lever arm and mount a micro switch. You could put an 'L'
> shaped tab on the arm using the existing hole to contact the switch if you
> need to move the assembly inboard to clear the fuel line.
Nope. That's what is typically done. But the routing of my MAP line doesn't allow
for that. I couldn't get a picture showing it, but extending the bracket would
require new fittings and a new MAP line to be fabricated. I'm trying to see
if there's a workaround.
> Or like I mentioned before, mount the switch remotely and activate it with a
slave rod (piano wire) from the lever arm...on either side (push or pull can work).
That's a little more complicated but allows you to work around space limitations
or obstructions if needed.
That's a thought. I'll have to look and see how much trouble that's going to be.
> Simple stuff...bunches of various options. I see no real need for something
complex.
Agreed. That's why I was thinking of a MAP switch that would close when the MAP
got down to around 12-13"
> BTW, I hope this you have already addressed this - that mounting clamp looks
not to be fully secured. You dont want to "pre-disaster" yourself and have the
throttle linkage come loose in flight. Just checking.
I'm a LONG way off from even starting the engine. Let alone moving under it's own
power. When things are tightened/secured, they get some torque seal. Until
then, it's easier to remove for other installations and modifications.
Thanks,
Don
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411442#411442
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| Subject: | Re: EXP 2 Bus workaround |
At 11:44 PM 10/25/2013, you wrote:
>I am still stumped as to why you would recommend one battery. I
>could agree if the one alternator is guaranteed to work without the
>battery in the circuit, but not without that backup. You must think
>batteries are much more reliable than I do.
Oky, let's ex[;pre that premise. What in your
studies and/or experience with batteries leads
you to believe that they demonstrate a risky,
in-service failure rate?
Before you add a second battery, are there things
that can be done to mitigate your concerns and
reduce in-service failures to acceptable risk
levels?
Recall that the original premise for dual batteries
had nothing to do with worries for battery failure
and everything to do with walling off known quantities
of energy off to do separate tasks . . . where one
of those tasks was critical to continued flight:
keep the engine running. The two battery concept was
never intended to be a hedge against the failure
of one battery.
Bob . . .
Message 4
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| Subject: | Re: EXP 2 Bus workaround |
At 01:51 AM 10/26/2013, you wrote:
On Oct 25, 2013, at 6:32 AM, Robert L. Nuckolls, III wrote:
Attached are the preliminary sketches for my current
thoughts on an architecture for single battery, single
alternator, electrically dependent engine. This line of
thinking is being developed as an preferred alternative
to Z-19.
Bob...I'm delighted that my queries have triggered your taking a
fresh look at Z-19...and presumably, Z-19RB.
This architecture has roots in Z-11 Three-Bus structure
with the addition of a Motive Power Bus (engine). With
the term E-bus already in legacy use, the MP-Bus terminology
offers a stand-out label that avoids confusion.
...perhaps it won't be too long before MP busses will morph into ones
intended for truly all electric power trains...
The major difference is the addition of the MP-bus having
normal feedpath from the main bus, alternate feedpath from
the battery . . . same as the E-Bus except BOTH pathways
have panel mounted switches. The e-bus is always hot any
time the main bus is hot, but the MP-Bus as power to the
engine needs to be controlled through both pathways.
I'm thinking that the EXP-bus can be folded into this
architecture by conversion of battery switch to DC master
and take alternator field through second pole. Convert
the 'avionice master' Engine A. Use switch between the
big red rockers as e-bus alternate feed. Switch to right
of Engine A is Engine B.
From the get-go, my intent has been to supplement the capabilities
of the EXP Bus to provide for the special requirements for a MPEFI
engine AND to provide the alternate feeds featured in AeroElectric's
Z-xx diagrams in case something goes amiss.
I question your suggestion to:
Use switch between the big red rockers as e-bus alternate feed.
Switch to right of Engine A is Engine B.
I'm reluctant to interpose within the row of EXP Bus rockers,
switches which would only be used during an emergency.
Conceptually, I much prefer the notion of having a row of rockers,
all of which are used in the course of normal operations...and a
second, distinctly different row of rockers which will only be used
during emergencies.
Please . . . purge the work EMERGENCY from your
thought processes. Things on airplanes break all
the time. If they did not, FBO maintenance shops
would be out of business and Jiffy-Lube could move
into the empty space while adding a wash-rack.
You have Plan-A, everything works in accordance
with the refined constellation of design goals.
Then there is Plan-B, something broke . . . a
condition that has been anticipated in our FEMA
and we're dealing with it under a sub-set of
the original design goals. Then there's Plan-C,
supported by some goodies in the flight bag
that describe yet a smaller sub-set of original
design goals.
An airplane configured artfully conducted FMEA
operating by a pilot who understands the machine's
strengths and weaknesses does not experience
electrical emergencies . . . only events of
in-service failure or wear-out that will need
to be hammered on once you've arrived at your
intended destination.
(The wide, red, Master switch at the left end...distinctive in both
width and color...is of course used both in normal and emergency ops.)
Organizing the panel in this manner...at least to me...sets the stage
for calm and cool actions when under stress.
I understand your desire for me to proceed w/ listing of elec loads
for all components...a task I recognise as essential...but first I
want to be confident that I understand the big picture. And the big
picture for me is how we supplement the capabilities of the EXP Bus
in order to have the benefits of engine and endurance busses with
alternate feeds from the battery.
The BIG picture is that drawing I published.
You're getting distracted by the existence of
the EXP-Bus.
Notwithstanding the shortcomings, some poor choices, and undoubtedly
some serious errors, the last diagram I posted (Revision #XX) did two
things of note:
First, it pulls power from the EXP Master Bus for the MP (engine) bus
from 2 - 11 amp circuits, AUX1 and AUX2. (...now I don't know exactly
how those 2 circuits can be combined, but something tells me there's
a way which is simple and direct...)
Second, the Revision XX diagram shows the EXP Avionics Bus powering
the E-bus (endurance) from a 7 amp circuit. (...btw, I don't
understand the notion that we should be rid of the avionics master
switch...). Also...note that w/ Skyview and the back up GPS both
having their own back up batteries, if either the Master switch or
the Avionics Master is turned off and the E-bus Alternate Feed is
energized, we'll be back in business w/ a full suite of avionics.
The avionics master switch was a flawed idea
from the get-go. I was at Cessna when the thing
was birthed and I've come to understand how
we marched off down that no-value-added
path. See:
http://tinyurl.com/pgcgx9m
It strikes me that this approach is elegant, simple, and direct; I
shudder at the thought of altering any part of the circuitry within
the EXP Bus other than changing some Fast-on spades of a couple of
switches and relabeling them.
Ignore the EXP=Bus for now, we need to
make the architecture work first.
I'm baffled when you write,
"Old avionics bus becomes e-bus."
There is presently an avionics master switch that
controls all power to a chunk of copper glued
to the epoxy-glas that distributes power to terminals
on the board through an array of poly-fuses. This
is your 'avionics' bus which I believe can become
your new e-bus.
...as I look at the circuit board of the EXP Bus, I haven't a clue
how this can happen and create the alternate feed intrinsic w/ the
e-bus concept...way outside my comfort zone to poke around in that
circuit board.
It's just "wires" glued to a piece of epoxy-glas.
Nothing happens on that assembly that a large
number of our contemporaries haven't done with
fuses, wires, breakers and switches. The marketing-hook
for an EXP-Bus is it's relative complexity for stuffing
a lot of activity into a small volume and then offering
it to the customer as, "Here, look at all these things
we did FOR you so that you don't HAVE to."
The question never asked and answered is, "Does that
assembly DO things that people who choose not to
use your product will wish they had included at
some later time?" In other words, what is the
return on investment for you having exchanged your
dollars for their time, talents and resources?
That's what we're doing here right now. The sketches
I published don't speak to how the EXP-Bus will be
'jeeped' (Old television vernacular for modifying
a piece of equipment to some new task not offered
by the designers) into the spirit and intent of
the new Z-figure. Let's assume for the moment that
EXP-Bus is not present. The sketches are not
a "Z-figure for EXP-Buses" . . . it's a new architecture
is a stand alone recipe for success crafted from
rudimentary ingredients. Making a practical
adaptation of an EXP-Bus to the task is a separate
activity we can tackle after the cake is in the oven.
It's just 'frosting' . . .
Bob . . .
Message 5
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| Subject: | Re: EXP 2 Bus workaround |
At 05:51 AM 10/26/2013, you wrote:
>
>FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work
>fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes
>up no more than 2 psi. even with my somewhat restrictive 5/16"
>return plumbing. Some fellows run both pumps for landing and
>takeoff. Selecting both on is the first thing we do if the engine is
>not running properly. Injector flow increases with the square root
>of pressure so that is not an issue since normal EFI pressures run
>around 38 psi above manifold pressure.
Good data sir. Thanks!
Bob . . .
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| Subject: | Re: EXP 2 Bus workaround |
>> Is anyone flying this combination of hardware? How much does
>> IAS need to be reduced to stop a windmilling prop? The few
>> times I stopped the prop on a TC airplane I had to really
>> work at it. The idea that one needs access to a starter
>> motor in flight is mostly without foundation. This is a
>> fact you need to resolve for your harware combination.
>
>Bob...I'm getting some data on this.
Does your engine feature a PSRU? If so, does it
include a spag-clutch on the propeller shaft
for mitigation of rotational vibration stresses
on the gearbox?
If so, then the prop windmills at all speeds and
does not back-drive the engine. But in any case,
pushing a starter button with the notion that a
starter will respond assumer is ales a battery contactor
is closed and FAT-wire power is also available to
the starter. Starter button is not an E-bus load.
Bob . . .
Message 7
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| Subject: | Re: EXP 2 Bus workaround |
On this list we have seen examples of internal battery failures and wire
connector failures and switch failures. Granted that these things
typically have low failure rates, but if they happen, you have no
backup. By going with one battery and not knowing if the alternator will
back you up you have elevated these failures to the status of a prop,
engine, wing or control surface failure.
John
On 10/26/2013 9:03 AM, Robert L. Nuckolls, III wrote:
> At 11:44 PM 10/25/2013, you wrote:
>> I am still stumped as to why you would recommend one battery. I could
>> agree if the one alternator is guaranteed to work without the battery
>> in the circuit, but not without that backup. You must think batteries
>> are much more reliable than I do.
>
> Oky, let's ex[;pre that premise. What in your
> studies and/or experience with batteries leads
> you to believe that they demonstrate a risky,
> in-service failure rate?
> Before you add a second battery, are there things
> that can be done to mitigate your concerns and
> reduce in-service failures to acceptable risk
> levels?
>
> Recall that the original premise for dual batteries
> had nothing to do with worries for battery failure
> and everything to do with walling off known quantities
> of energy off to do separate tasks . . . where one
> of those tasks was critical to continued flight:
> keep the engine running. The two battery concept was
> never intended to be a hedge against the failure
> of one battery.
>
> Bob . . .
>
> *
>
>
> *
Message 8
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 26, 2013, at 3:51 AM, Ken wrote:
> FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work
fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes up
no more than 2 psi. even with my somewhat restrictive 5/16" return
plumbing. Some fellows run both pumps for landing and takeoff. Selecting
both on is the first thing we do if the engine is not running properly.
Injector flow increases with the square root of pressure so that is not
an issue since normal EFI pressures run around 38 psi above manifold
pressure.
Thanks Ken...I stand corrected...my engine at 1.8 L is a tad smaller
than your Legacy...it's set up w/ 3/8" fuel supply line and a 1/4"
return line using R9 injector hose aft of my firewall. I believe the
fuel pressure regulator has been set to factor in whatever restrictive
backpressure the 1/4" return line contributes.
Ron Carr at RAM Performance sez my engine's fuel pressure will be 38 psi
at idle and rise to 43 psi at WOT.
(I have not discussed the dual pump issues w/ him because he sells his
engines with only one pump.)
Fred
Message 9
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| Subject: | Re: EXP 2 Bus workaround |
Fred, Bob, et al, I have no dog in this fight, I've just been following the
discussion but I've got to ask; with all these workarounds you're doing to
make the EXPBus work with your airplane's systems, what is it buying you?
The Spruce description of the EXPBus is all about easy squeazy installation
and time savings, yet you're being forced into more and more redesign and
adaptation in order to make it work for you. I realize that you're a long
way down the road with this thing but have you thought about just grabbing
a clean sheet of paper and sending the EXPBus to eBay?
Rick Girard
On Sat, Oct 26, 2013 at 8:58 AM, John W Livingston
<livingjw@earthlink.net>wrote:
> On this list we have seen examples of internal battery failures and wire
> connector failures and switch failures. Granted that these things typically
> have low failure rates, but if they happen, you have no backup. By going
> with one battery and not knowing if the alternator will back you up you
> have elevated these failures to the status of a prop, engine, wing or
> control surface failure.
>
> John
>
>
> On 10/26/2013 9:03 AM, Robert L. Nuckolls, III wrote:
>
> At 11:44 PM 10/25/2013, you wrote:
>
> I am still stumped as to why you would recommend one battery. I could
> agree if the one alternator is guaranteed to work without the battery in
> the circuit, but not without that backup. You must think batteries are much
> more reliable than I do.
>
>
> Oky, let's ex[;pre that premise. What in your
> studies and/or experience with batteries leads
> you to believe that they demonstrate a risky,
> in-service failure rate?
>
>
> Before you add a second battery, are there things
> that can be done to mitigate your concerns and
> reduce in-service failures to acceptable risk
> levels?
>
> Recall that the original premise for dual batteries
> had nothing to do with worries for battery failure
> and everything to do with walling off known quantities
> of energy off to do separate tasks . . . where one
> of those tasks was critical to continued flight:
> keep the engine running. The two battery concept was
> never intended to be a hedge against the failure
> of one battery.
>
> **
>
> Bob . . .
>
> *
>
> *
>
> **
>
>
> *
>
> *
>
>
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
Message 10
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| Subject: | Re: EXP 2 Bus workaround |
At 09:57 AM 10/26/2013, you wrote:
>Fred, Bob, et al, I have no dog in this fight, I've just been
>following the discussion but I've got to ask; with all these
>workarounds you're doing to make the EXPBus work with your
>airplane's systems, what is it buying you? The Spruce description of
>the EXPBus is all about easy squeazy installation and time savings,
>yet you're being forced into more and more redesign and adaptation
>in order to make it work for you. I realize that you're a long way
>down the road with this thing but have you thought about just
>grabbing a clean sheet of paper and sending the EXPBus to eBay?
For me, this discussion is NOT an attempt to
craft a Z-Figures for EXP-Bus. It's a new look
at Z-19 and other manifestations of two-battery
installations to explore well reasoned alternatives.
When and if the new Z-figure makes it to the back
of the book, then well see if we can fiddle with
an EXP-Bus to achieve the same architecture crafted
to design goals.
Bob . . .
Message 11
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| Subject: | Re: EXP 2 Bus workaround |
At 09:44 AM 10/26/2013, you wrote:
>On Oct 26, 2013, at 3:51 AM, Ken wrote:
>
>>FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy
>>work fine with a oem regulator all of 1990 to 1994 vintage.
>>Pressure goes up no more than 2 psi. even with my somewhat
>>restrictive 5/16" return plumbing. Some fellows run both pumps for
>>landing and takeoff. Selecting both on is the first thing we do if
>>the engine is not running properly. Injector flow increases with
>>the square root of pressure so that is not an issue since normal
>>EFI pressures run around 38 psi above manifold pressure.
>
>Thanks Ken...I stand corrected...my engine at 1.8 L is a tad smaller
>than your Legacy...it's set up w/ 3/8" fuel supply line and a 1/4"
>return line using R9 injector hose aft of my firewall. I believe the
>fuel pressure regulator has been set to factor in whatever
>restrictive backpressure the 1/4" return line contributes.
>
>Ron Carr at RAM Performance sez my engine's fuel pressure will be 38
>psi at idle and rise to 43 psi at WOT.
The question to be answered for evolving this
new architecture is whether or not having two
pumps on at the same time represents any kind
of hazard.
The second pump is included to mitigate the
failure of the first pump. The first pump is
presently powered any time the MP-Bus is hot.
If the pump works, then the second pump is
not needed. If the first pump fails, the second
pump is available. At no time has anyone
suggested that the pumps should be operated
simultaneously on purpose.
Bob . . .
Message 12
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| Subject: | Re: EXP 2 Bus workaround |
> Is anyone flying this combination of hardware? How much does
> IAS need to be reduced to stop a windmilling prop? The few
> times I stopped the prop on a TC airplane I had to really
> work at it. The idea that one needs access to a starter
> motor in flight is mostly without foundation. This is a
> fact you need to resolve for your harware combination.
Somewhat different hardware but indicative. With a 1.92 gear ratio and
a 3 bladed 72" non-tapered warp prop my ej22 windmills down to below 40
knots. However if I do intentionally stop it (difficult to do with a
best glide speed of about 65 knots), a 120 knot dive is insufficient to
get a restart. More interesting was that unlike many airplanes, my Rebel
has about the same glide ratio whether windmilling or stopped which
surprised me. Obviously I do not have one of the sprag clutch type
arrangements that have been so troublesome...
Ken
Message 13
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 26, 2013, at 7:57 AM, Richard Girard wrote:
> Fred, Bob, et al, I have no dog in this fight, I've just been
following the discussion but I've got to ask; with all these workarounds
you're doing to make the EXPBus work with your airplane's systems, what
is it buying you? The Spruce description of the EXPBus is all about easy
squeazy installation and time savings, yet you're being forced into more
and more redesign and adaptation in order to make it work for you. I
realize that you're a long way down the road with this thing but have
you thought about just grabbing a clean sheet of paper and sending the
EXPBus to eBay?
Good question Rick...and one I've asked myself many times. My answer has
been that I'll chuck the EXP Bus when I reach the conclusion that doing
so will solve more problems than it creates. I'm still a long way from
that.
Your first question..."what is it buying you?"...is an even better
question, and I regret that I was simply too ignorant to read between
the lines of the marketing hype...I confess to have been dazzled by the
EXP's obvious complexity (to what end?) and my belief that "I guess I
need to buy one of these, cause I sure wouldn't want to trust myself to
build one".
As I presently understand things, the EXP can serve as my main power
distribution bus and provides circuits which can be used to power an
engine bus (or Motive Power Bus, to use Bob's new term) and an endurance
bus, both of which want to have alternate power feeds direct from the
battery.
All this seems fine and doable without making circuitry changes within
the EXP, something I'm loath to do, primarily because of my inexperience
and unfamiliarity w/ things electronic.
I can only commend Bob for his patience with me,
Fred
Message 14
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| Subject: | Re: EXP 2 Bus workaround |
At 08:58 AM 10/26/2013, you wrote:
>On this list we have seen examples of internal battery failures and
>wire connector failures and switch failures. Granted that these
>things typically have low failure rates, but if they happen, you
>have no backup. By going with one battery and not knowing if the
>alternator will back you up you have elevated these failures to the
>status of a prop, engine, wing or control surface failure.
Let's concentrate on battery failures . . . and
the failure of components that hook that battery
to ground and the contactor stud.
What was the nature of failures internal to the
battery? What was the nature of failure for
any wires/connectors for which you have data?
Yes. Propellers have flown off the end of crankshafts,
wheels have departed their axles, elevator push-rods
have become disconnected. We read about and ponder these
events . . . did any one of these FEMA prompt recommendations
for dual engines, an extra landing gear strut and wheel
or perhaps splitting the elevator into two halves with
independent pushrods?
The rational response to such stories is to move
avoidance for root cause into prominent positions
for attention to detail. I've observed many
times in these writings that the greatest risk
to the airborne mission is the human element; a
risk for missing/ignoring critical fundamentals.
Can we deduce what attention to detail is needed
to make a battery as reliable as your prop bolts?
Bob . . .
Message 15
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| Subject: | Re: EXP 2 Bus workaround |
Bob...you asked:
> Is anyone flying this combination of hardware?
I asked a pal flying a RAM Sube powered Europa the following
questions:
>> In your bird, have you ever stopped your engine in flight?
>>
>> .If so, did the prop stop or windmill?
>>
>> If the prop stopped, how did you get it spinning again?
>>
>> Can you spin your starter w/ the Master Switch off?
>>
>> If not, would you like to be able to?
...and got this reply...not much help unfortunately.
Fred
> Hi Fred - no I've never stopped it. I thought about flying to an
aiport 40 miles north that has an 12000 ft runway and climb to 10000 ft
at 6 AM when no traffic was around and turn it off but haven't done it
yet.
>
> I can turn everything off but the fuel pumps and ignition and the
engine will run but I never thought of whether the starter
> would work - duh!!
>
> I'll have to check that and get back to you. I need to see if the
trim works with everything turned off as well. I'm wondering if with
the ac trimmed for cruise whether I would still have enough elevator for
the landing flare.
>
>
> XXXX
>
> From: fklein@orcasonline.com
> Subject: a Europa query
> Date: Fri, 25 Oct 2013 22:04:53 -0700
> To: XXXX@hotmail.com
>
> XXXX
>
> In your bird, have you ever stopped your engine in flight?
>
> .If so, did the prop stop or windmill?
>
> If the prop stopped, how did you get it spinning again?
>
> Can you spin your starter w/ the Master Switch off?
>
> If not, would you like to be able to?
>
>
> Sorry for all the questions...they are a consequence of an online
conversation I'm having with Bob Nuckolls at AeroElectric-list...excerpt
below:
>
>
> > (8) Starter can control from main bus.
>
> True...and...w/ my particular combination of engine,
reduction ratio, propeller, and aircraft performance envelope, although
I THINK that with engine out, prop would windmill sufficient to restart
engine, if Master switch was OFF, I'd like to be able to spin the
starter...that was the INTENT of what the diagram shows...What do you
think?...I'm unsure as to whether or not the wiring diagram allows for
that to happen.
>
> Is anyone flying this combination of hardware? How much does
> IAS need to be reduced to stop a windmilling prop? The few
> times I stopped the prop on a TC airplane I had to really
> work at it. The idea that one needs access to a starter
> motor in flight is mostly without foundation. This is a
> fact you need to resolve for your harware combination.
>
> Thanks once again for your help,
>
> Fred
Message 16
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 26, 2013, at 8:49 AM, Ken wrote:
>
> > Is anyone flying this combination of hardware? How much does
> > IAS need to be reduced to stop a windmilling prop? The few
> > times I stopped the prop on a TC airplane I had to really
> > work at it. The idea that one needs access to a starter
> > motor in flight is mostly without foundation. This is a
> > fact you need to resolve for your harware combination.
>
> Somewhat different hardware but indicative. With a 1.92 gear ratio
and a 3 bladed 72" non-tapered warp prop my ej22 windmills down to below
40 knots. However if I do intentionally stop it (difficult to do with a
best glide speed of about 65 knots), a 120 knot dive is insufficient to
get a restart. More interesting was that unlike many airplanes, my Rebel
has about the same glide ratio whether windmilling or stopped which
surprised me. Obviously I do not have one of the sprag clutch type
arrangements that have been so troublesome...
Ken...interesting...my PSRU ratio is 1.9 to 1.0 and I too do not have a
sprag clutch...Fred
Message 17
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| Subject: | Re: EXP 2 Bus workaround |
>>>Can you spin your starter w/ the Master Switch off?
Why would you want access to the
starter with the master switch off?
Under what conditions would you first
have the switch off and then find that
the engine has assumed a condition that
needs encouragement to get running again?
Assuming that the engine is at risk for
doing such a thing, what prevents you
from turning the master switch back on?
Bob . . .
Message 18
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 26, 2013, at 10:09 AM, Robert L. Nuckolls, III wrote:
>>>> Can you spin your starter w/ the Master Switch off?
>
> Why would you want access to the
> starter with the master switch off?
> Under what conditions would you first
> have the switch off and then find that
> the engine has assumed a condition that
> needs encouragement to get running again?
> Assuming that the engine is at risk for
> doing such a thing, what prevents you
> from turning the master switch back on?
Bob...my imagination knows no limits...I'm thinkin the Master's off
after detecting smoke and acrid smells coming from the panel...I'm
wanting to avoid the risk of flippin the Master back on and exacerbating
the situation which caused me to flip it off in the first place.
Fred
Message 19
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| Subject: | Re: EXP 2 Bus workaround |
>Bob...my imagination knows no limits...I'm thinkin the Master's off
>after detecting smoke and acrid smells coming from the panel...I'm
>wanting to avoid the risk of flippin the Master back on and
>exacerbating the situation which caused me to flip it off in the first place.
Okay, so that's a really big failure or a combination of
more than one failure giving you both Smoke + engine quits.
If you've suffered an event that stops the engine AND
smells bad . . . well . . .
The configuration on which we're sifting the sands
will allow you to turn off every switch except Engine A
without killing the engine electrically. Hmmm . . . perhaps
Engine A needs to run from the battery, Engine B from the
main bus. Now, the statement I made above is true.
Even so, unless you've got a clutched PRSU then you're
not going to need the starter anyhow. If the engine
has lost power due to same event that's causing smoke
. . . it's likely that mitigation of risk for
that cause is far outside the manipulation of any switches.
Bob . . .
Message 20
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 26, 2013, at 10:56 AM, Robert L. Nuckolls, III wrote:
> Even so, unless you've got a clutched PRSU then you're
> not going to need the starter anyhow. If the engine
> has lost power due to same event that's causing smoke
> . . . it's likely that mitigation of risk for
> that cause is far outside the manipulation of any switches.
Bob...I wouldn't disagree with you.
The origin of this question arose when you noted that my Revision XX
diagram showed the starter switch fed from the engine (sorry, MP) bus
rather than the main bus...I still don't see the down side if I were to
do this.
Fred
Message 21
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| Subject: | EXP 2 Bus workaround |
Fred;
Not meaning to be critical or judgmental, but your "properly designed" and
maintained electrical system has somehow found a way to generate "smoke in
the cockpit" and you've turned off the master switch. So far so good.
The electrical problem (or fire) has progressed to the point of stopping the
engine and now you want to be further distracted by operating the starter to
turn over the failed engine rather than to "FLY THE AIRCRAFT" to a
controlled landing ????
In order to stop, the engine must have been denied either fuel, spark or
mechanical integrity, and for it to restart you must determine and restore
whichever element is missing before the starter will be of any use. (and
you've had to aerodynamically stall the airframe to stop the engine's wind
milling rotation) With all the redundancies and complexities you're
proposing you're unlikely to troubleshoot and solve the problem in the air.
It's excellent to think up and have a solution for the various scenarios,
but at some point you need to follow the KISS principle and not layer one
"what if" on top of another. The likelihood of two or more failures on any
one flight on a properly designed and maintained aircraft are exceeding
unlikely.
By all means design for any single "what if" or failure you can possibly
conceive, but to layer one on top of another on top of another and try to
have a work-around is just going to increase the likelihood of a problem not
decrease it.
Just my unsolicited two cents which you're quite entitled to delete or
ignore (or deposit in the bank if you so desire)
Bob McC
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Fred
Klein
Sent: Saturday, October 26, 2013 1:30 PM
Subject: Re: AeroElectric-List: EXP 2 Bus workaround
On Oct 26, 2013, at 10:09 AM, Robert L. Nuckolls, III wrote:
Can you spin your starter w/ the Master Switch off?
Why would you want access to the
starter with the master switch off?
Under what conditions would you first
have the switch off and then find that
the engine has assumed a condition that
needs encouragement to get running again?
Assuming that the engine is at risk for
doing such a thing, what prevents you
from turning the master switch back on?
Bob...my imagination knows no limits...I'm thinkin the Master's off after
detecting smoke and acrid smells coming from the panel...I'm wanting to
avoid the risk of flippin the Master back on and exacerbating the situation
which caused me to flip it off in the first place.
Fred
Message 22
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| Subject: | Re: EXP 2 Bus workaround |
At 01:21 PM 10/26/2013, you wrote:
>On Oct 26, 2013, at 10:56 AM, Robert L. Nuckolls, III wrote:
>
>>Even so, unless you've got a clutched PRSU then you're
>> not going to need the starter anyhow. If the engine
>> has lost power due to same event that's causing smoke
>> . . . it's likely that mitigation of risk for
>> that cause is far outside the manipulation of any switches.
>
>Bob...I wouldn't disagree with you.
>
>The origin of this question arose when you noted that my Revision XX
>diagram showed the starter switch fed from the engine (sorry, MP)
>bus rather than the main bus...I still don't see the down side if I
>were to do this.
You're still wrapped around the axles of distraction.
Let's get your list of loads spread out on the
hypothetical architecture I published . . . and sift
the FEMA/operational sands for that configuration.
Then we can begin to study a means by which the EXP-Bus
can morph into the same architecture. It may be that
the starter switch gets powered from someplace different
simply because you've run out of polyfuses on a particular
bus. But downside or upside cannot be discussed until after
roll-call.
I have a finite amount of time to offer to this process . . .
Bob . . .
Message 23
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| Subject: | EXP 2 Bus workaround |
At 01:36 PM 10/26/2013, you wrote:
>Fred;
>
>Not meaning to be critical or judgmental, but your "properly
>designed" and maintained electrical system has somehow found a way
>to generate "smoke in the cockpit" and you've turned off the master
>switch. So far so good.
>The electrical problem (or fire) has progressed to the point of
>stopping the engine and now you want to be further distracted by
>operating the starter to turn over the failed engine rather than to
>"FLY THE AIRCRAFT" to a controlled landing ????
Gently my friend. Members here on the is are, for the most
part, not aviation professionals. Fewer still have a grasp
on the materials, processes and what-if analysis that goes
into crafting the elegant solution. There was a time when
Z-19 was considered a 'solution' and to be sure, every feature
on it operates in a predicable manner with no surprises.
Fred's willingness to participate in this exercise has
prompted a review of the ideas on which Z-19 stands along
with brain-storming for simpler alternatives based on
better ideas.
Fred has mentioned that a friend of his opined that
many band-aid-on-top-of-band-aid designs on airplanes
to be products of ignorance and poor logic. Yup, those
things happen.
I've watched it my whole career in situations where I
was one of many and with little influence. It doesn't even
take a design by committed/regulation to produce an
accident waiting to happen. Review the materials I posted
on the N811HB accident.
Many individuals who monitor the List have expressed
a reluctance to post lest they become targets of
words that fall outside the realm of entertaining
and persuasive information.
This is a classroom and it's my greatest wish that
people carry knowledge out the door that adds value to
their aviation experience.
Bob . . .
Message 24
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| Subject: | Re: EXP 2 Bus workaround |
I have learned a lot in your classroom. Thanks Bob.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411476#411476
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| Subject: | Re: EXP 2 Bus workaround |
At 02:51 PM 10/26/2013, you wrote:
>
>I have learned a lot in your classroom. Thanks Bob.
. . . and you've been an honorable participant for
which I thank YOU.
Bob . . .
Message 26
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| Subject: | EXP 2 Bus workaround |
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L.
Nuckolls, III
Sent: Saturday, October 26, 2013 3:38 PM
Subject: RE: AeroElectric-List: EXP 2 Bus workaround
At 01:36 PM 10/26/2013, you wrote:
Fred;
Not meaning to be critical or judgmental, but your =13properly
designed=14 and
maintained electrical system has somehow found a way to generate
=13smoke in
the cockpit=14 and you=12ve turned off the master switch. So far so
good.
The electrical problem (or fire) has progressed to the point of stopping
the
engine and now you want to be further distracted by operating the
starter to
turn over the failed engine rather than to =13FLY THE AIRCRAFT=14 to a
controlled landing ????
Gently my friend.
Was trying to be. If it came across differently, that was not the
intention.
I apologize.
Members here on the is are, for the most
part, not aviation professionals. Fewer still have a grasp
on the materials, processes and what-if analysis that goes
into crafting the elegant solution. There was a time when
Z-19 was considered a 'solution' and to be sure, every feature
on it operates in a predicable manner with no surprises.
Agree
Fred's willingness to participate in this exercise has
prompted a review of the ideas on which Z-19 stands along
with brain-storming for simpler alternatives based on
better ideas.
And many of his (and others) scenarios point to the areas of potential
improvement.
Fred has mentioned that a friend of his opined that
many band-aid-on-top-of-band-aid designs on airplanes
to be products of ignorance and poor logic. Yup, those
things happen.
Part of the point of my original comment was intended to not lose sight
of
that philosophy.
I've watched it my whole career in situations where I
was one of many and with little influence. It doesn't even
take a design by committed/regulation to produce an
accident waiting to happen. Review the materials I posted
on the N811HB accident.
Exactly.
Many individuals who monitor the List have expressed
a reluctance to post lest they become targets of
words that fall outside the realm of entertaining
and persuasive information.
Myself included, but part of the issue is not that the thoughts are
intended
to be critical or demeaning in any way shape or form but that perhaps
the
command of English usage or even the degree of articulation is lacking
so
that comments are misinterpreted.
This is a classroom and it's my greatest wish that
people carry knowledge out the door that adds value to
their aviation experience.
Absolutely. I've learned immeasurably through lurking here many years,
but
as you've stated I'm often reluctant to share because of the fear of
misstating my thoughts or verbalizing in a way that is open to
misinterpretation. E-mails lack the intonations of a face to face
conversation that sometimes conveys as much meaning as the actual words.
Bob . . .
Once again, if my wording was inappropriate, I apologize. I'll keep
quiet
now.
Bob McC
Message 27
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| Subject: | EXP 2 Bus workaround |
> Gently my friend.
>Was trying to be. If it came across differently, that was not the
>intention. I apologize.
Understand. Perhaps is was the bold, technicolor font that
offered a poor first blush. That is a down-side for keyboard
communications. We can be deprived of useful communications
data when relying on the written word.
No value to be shared in 'being quiet' . . . the ideas you
proffered were sound.
I'm kind of 'stoked with this thread. There's not been
a new z-figure in years. This is a good thing that
these things get debated. Fred's worries about the
smoke+silence failure prompted a thought on my part
that perhaps Engine A switch ought to power from the
battery with backup being Engine B from the main bus.
This is backwards from how we've used the e-bus but it
does suggest better human factors for powering down
the electrics while leaving the engine up.
Bob . . .
Message 28
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 26, 2013, at 11:36 AM, Bob McCallum wrote:
> Not meaning to be critical or judgmental, but your =93properly
designed=94 and maintained electrical system has somehow found a way to
generate =93smoke in the cockpit=94 and you=92ve turned off the master
switch. So far so good.
Thanks Bob M....I needed that...sometimes my imagination needs a
comeuppance and a breath of fresh air...Fred
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| Subject: | Re: EXP 2 Bus workaround |
On Oct 26, 2013, at 12:25 PM, Robert L. Nuckolls, III wrote:
> You're still wrapped around the axles of distraction.
> Let's get your list of loads spread out on the
> hypothetical architecture I published . . . and sift
> the FEMA/operational sands for that configuration.
I'm on it Bob...thanks, Fred
Message 30
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| Subject: | Re: EXP 2 Bus workaround |
I have drawn a schematic (attached) for Fred using the EXP Bus. It might not be
as good as Bob's designs, but I think it is better than many TC aircraft electrical
systems. Fred definitely does not want to take a soldering iron to the
circuit board. So I could not make some changes that I would like to. If Fred
decides to use my schematic, the only changes that he will have to make will
be pulling fast-on connectors off from switches and moving them around. The
main feature of this schematic is the addition of a master relay that is in
parallel with the battery contactor. Not to worry, this relay can not be energized
while starting the engine. The switch, that is normally the master switch,
must be off in order to start the engine. This also serves as a theft deterrent
because a thief will turn on what he thinks is the master switch, but the
engine will not start. The former avionics master switch now controls the
battery contactor. Since the new master switch also turns on the alternator field,
the former ALT switch can now be used for the second fuel pump. I think
that the EXP Bus has enough switches so that additional switches will not have
to be added to the panel.
Now that I am all done with the schematic and stand back and look at the big
picture, I see that in case the EXP Bus smokes, shutting off the master switches
will also kill the engine. How to fix that? How about an Engine bus fed by
the master relay and also by a diode from the EXP Bus?
Comments are welcome. Just do not be too hard on me. :-)
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=411483#411483
Attachments:
http://forums.matronics.com//files/fred_exp_2_bus_200.dwg
http://forums.matronics.com//files/fred_exp_2_bus_152.pdf
Message 31
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| Subject: | EXP 2 Bus workaround - Master Solenoid Failure |
=0A=0AI really enjoy this what-if stuff, so here goes...=0A=0A=0AI'm referr
ing to Bob's drawing sent out yesterday afternoon, Z-08_Full.pdf.- It app
ears that people are touching on this issue but I have not seen it clearly
stated. =0A=0A=0AGiven:=0A1. Stated design goal: To be able to survive any
single component failure w/ little or no drama.=0A=0A2. Electrically-depend
ent engine=0A=0A3. Engine/prop does not windmill, because of some kind of P
SRU =0A4. You are flying w/ Engine A switch On=0A5. Engine B switch Off=0A
=0A=0AScenario:=0A1. You are in flight and Main Batt Contactor fails (coil
burns up, loose wire, whatever)=0A=0A2. Engine shuts down, prop stops=0A=0A
3. Pilot takes several seconds to gather his thoughts=0A4. Pilot turns Engi
ne B switch On - power restored to engine systems except starter=0A=0A5. Pi
lot hits starter button to re-light.- Starter inop because failed Main Ba
tt Contactor is in series w/ Starter Contactor.=0A6. Forced landing=0A=0A7.
Failure to meet design goal - single component failure causes forced landi
=============
Message 32
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| Subject: | Re: EXP 2 Bus workaround - Master Solenoid Failure |
At 08:47 PM 10/26/2013, you wrote:
>I really enjoy this what-if stuff, so here goes...
>
>I'm referring to Bob's drawing sent out yesterday afternoon,
>Z-08_Full.pdf. It appears that people are touching on this issue
>but I have not seen it clearly stated.
>
>Given:
>1. Stated design goal: To be able to survive any single component
>failure w/ little or no drama.
>2. Electrically-dependent engine
>3. Engine/prop does not windmill, because of some kind of PSRU
Turns out not true.
>4. You are flying w/ Engine A switch On
>5. Engine B switch Off
>
>Scenario:
>1. You are in flight and Main Batt Contactor fails (coil burns up,
>loose wire, whatever)
Okay . . .
>2. Engine shuts down, prop stops
No, the alternator doesn't quite producing just
because the battery is off line. Further, based on
the exchange with Fred/Bob Mc/Bob N I realized that
the Engine source coming from the battery should
be switched by ENG A. Next iteration will show that.
But it's also possible that the pilot would be unaware
of the loss of contactor until the next flight
when turning battery switch on doesn't light things up.
>3. Pilot takes several seconds to gather his thoughts
>4. Pilot turns Engine B switch On - power restored to engine systems
>except starter
. . . but engine IS windmilling
>5. Pilot hits starter button to re-light. Starter inop because
>failed Main Batt Contactor is in series w/ Starter Contactor.
>6. Forced landing
>7. Failure to meet design goal - single component failure causes
>forced landing :(
>8. Thanks for playing...
inaccurate statement of premises . . .
Bob . . .
Message 33
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| Subject: | Re: EXP 2 Bus workaround - Master Solenoid Failure |
At 10:15 PM 10/26/2013, you wrote:
><nuckolls.bob@aeroelectric.com>
>
>At 08:47 PM 10/26/2013, you wrote:
>
>>I really enjoy this what-if stuff, so here goes...
>>
>>I'm referring to Bob's drawing sent out yesterday afternoon,
>>Z-08_Full.pdf. It appears that people are touching on this issue
>>but I have not seen it clearly stated.
Actually, there IS a compelling reason to move the
starter button source to the MP-Bus . . .
E-bus and Main bus on the EXP-Bus assembly have
fixed numbers of protected load-taps. Moving the
starter control to the MP-Bus frees up a load-tap
on the EXP-Bus.
But this still doesn't help you use the starter
in-flight with a contator crapped . . . you may be
able to energize the starter contactor but because
the battery contactor is open, there's no FAT wire
power to the contactor.
Bob . . .
Message 34
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| Subject: | Re: EXP 2 Bus workaround - Master Solenoid Failure |
=0AI 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-d
ependent ).=0A=0AHowever, I don't think you can categorically say that ALL
engines will windmill.- In addition some flight conditions may cause a wi
ndmilling prop to stop.- A possible scenario: The pilot becomes task satu
rated on the electrical failure and lets the airspeed bleed down and the pr
op stops.=0A=0A=0ADooh! I forgot about the alternator - BUT - I've never tr
usted an alternator that was not connected to a battery, therefore I would
be reluctant to have that as a fall back.=0A=0A=0AWhat about moving the sta
rter feed to the battery side of the master?=0A=0A=0A-Jeff=0A=0A=0A=0A_____
___________________________=0A From: "Robert L. Nuckolls, III" <nuckolls.bo
b@aeroelectric.com>=0ATo: aeroelectric-list@matronics.com =0ASent: Saturday
, October 26, 2013 8:15 PM=0ASubject: Re: AeroElectric-List: EXP 2 Bus work
around - Master Solenoid Failure =0A =0A=0A--> AeroElectric-List message
posted by: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0A=0AA
t 08:47 PM 10/26/2013, you wrote:=0A=0A> I really enjoy this what-if stuff,
so here goes...=0A> =0A> I'm referring to Bob's drawing sent out yesterday
afternoon, Z-08_Full.pdf.- It appears that people are touching on this i
ssue but I have not seen it clearly stated.=0A> =0A> Given:=0A> 1. Stated d
esign goal: To be able to survive any single component failure w/ little or
no drama.=0A> 2. Electrically-dependent engine=0A> 3. Engine/prop does not
windmill, because of some kind of PSRU=0A=0A- Turns out not true.=0A=0A
> 4. You are flying w/ Engine A switch On=0A> 5. Engine B switch Off=0A>
=0A> Scenario:=0A> 1. You are in flight and Main Batt Contactor fails (coil
burns up, loose wire, whatever)=0A=0A- Okay . . .=0A=0A> 2. Engine shut
s down, prop stops=0A=0A=0A- No, the alternator doesn't quite producing
just=0A- because the battery is off line. Further, based on=0A- the e
xchange with Fred/Bob Mc/Bob N I realized that=0A- the Engine source com
ing from the battery should=0A- be switched by ENG A. Next iteration wil
l show that.=0A=0A- But it's also possible that the pilot would be unawa
re=0A- of the loss of contactor until the next flight=0A- when turnin
g battery switch on doesn't light things up.=0A=0A> 3. Pilot takes several
seconds to gather his thoughts=0A> 4. Pilot turns Engine B switch On - powe
r restored to engine systems except starter=0A=0A- . . . but engine IS w
indmilling=0A=0A> 5. Pilot hits starter button to re-light.- Starter inop
because failed Main Batt Contactor is in series w/ Starter Contactor.=0A>
6. Forced landing=0A> 7. Failure to meet design goal - single component fai
lure causes forced landing :(=0A> 8. Thanks for playing...=0A=0A- inaccu
==============
Message 35
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| Subject: | Battery contactor failure |
At 12:00 AM 10/27/2013, you wrote:
>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 ).
Only if the fuel is delivered by engine driven pump
or gravity. The ignition is electronic driven directly
from magnets on the starter ring gear.
>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.
That's s double failure again. Failure tolerant systems
with a plan-b do not saturate pilots.
>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.
Because you know them to be unreliable or simply
don't know. Actually, Cessna and others who opted
for the split rocker switch were probably in violation
of legacy design goals.
Until that time, airplanes flew nicely on either
battery, generator or both. When the alternator
came along, the airframe guys elected to put
alternators on even tho they were not plug-n-play
for the failure tolerance offered by generators.
The Bonanza and Barons continued to offer alternator-
only operations but if I recall correctly, the Liberal
airplanes had split rockers.
PM alternators are easy to get on-line without a
battery and it may well be that belt-driven alternators
on a Lycoming are too. They run very fast. I need to
get some time on B&C's test bench and run some experiments.
>What about moving the starter feed to the battery side of the master?
If you're willing to have an always hot feeder to a
starter contactor . . .
Bob . . .
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