Today's Message Index:
----------------------
1. 04:57 AM - Re: 2-10 SWITCH - Can this be done? (Sam Hoskins)
2. 05:47 AM - Another leaking battery (earl_schroeder@juno.com)
3. 07:05 AM - Re: 2-10 SWITCH - Can this be done? (Robert L. Nuckolls, III)
4. 07:40 AM - Re: 2-10 SWITCH - Can this be done? (Sam Hoskins)
5. 08:03 AM - Re: 2-10 SWITCH - Can this be done? (Sam Hoskins)
6. 08:21 AM - Re: Z13/8 Battery Contactor Failure (Eric M. Jones)
7. 09:29 AM - Re: Z13/8 Battery Contactor Failure (Robert L. Nuckolls, III)
8. 10:58 AM - Re: Alternator noise (Robert L. Nuckolls, III)
9. 11:20 AM - B&C S700-2-11 switch configuration (Sam Hoskins)
10. 06:20 PM - MaxDim Group Buy Opportunity (Phil Samuelian)
11. 08:04 PM - Re: 2-10 SWITCH - Can this be done? (Ken)
12. 10:19 PM - Fast-On Tabs and Soldering (Dave VanLanen)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: 2-10 SWITCH - Can this be done? |
Yes, I probably am over complicating the matter. In fact, I'm sure of it.
Armed with a wide set of possibilities and a good CAD program, I can merril
y
spend hours and hours woring on all sorts of permutations.
Now I'll spend a little time trying to simplicate the thing. I appreciate
the reality check.
Thanks.
Sam
www.samhoskins.blogspot.com
On Mon, Nov 24, 2008 at 1:38 PM, Peter Pengilly <peter@sportingaero.com>wro
te:
> Sam,
>
>
> I think you are over complicating the matter ' I am assuming that the
> engine will run on either the A or the B system. Why not wire the whole o
f
> the A system from the main bus and the whole of the B system from the eng
ine
> bus? Both systems become completely independent and you have 2 completely
> redundant systems. There is no confusion as to which side of the
> ECU/pump/etc is running on what.
>
>
> If you suspect any kind of failure switch off the system currently in use
> and switch on the other one. Fly to the nearest airport and investigate t
he
> failure on the ground. Use both systems regularly so you trust them both.
> Any further redundancy perhaps is overkill and may just introduce further
> (unintended?) failure modes.
>
>
> Regards, Peter
>
>
> -----Original Message-----
> *From:* owner-aeroelectric-list-server@matronics.com [mailto:
> owner-aeroelectric-list-server@matronics.com] *On Behalf Of *Sam Hoskins
> *Sent:* 24 November 2008 16:53
> *To:* aeroelectric-list@matronics.com
> *Subject:* Re: AeroElectric-List: 2-10 SWITCH - Can this be done?
>
>
> Bob,
>
> Here are my basic thoughts and rational on the design.
>
> The RWS EFI controller <http://www.rotaryaviation.com/eficont.html> (ECU)
> has two separate Ignition/fuel injection controllers mounted on a single
> board. These are labeled as A & B. They are almost identical and separat
e.
>
> They allow separate +12V supply inputs, as well as separate ignition and
> fuel injector output triggers. The two battery busses, main and engine,
can
> each supply the A or B sides of the ECU.
>
> I am able to select a feed from either the main or the engine battery bus
> and supply it to either the A input of the B input. On my drawing, the
> engine bus is sometimes reffered to as "backup".
>
> Adding to that, are two Walbro fuel pumps, and here I continued a similar
> thought pattern. That is, either the main battery bus or the engine batt
ery
> bus would feed either the main EFI pump, or it's backup. The two Facet
> pumps transfer fuel from the main and aux tanks to the header supply tank
.
>
> All of this adds up to a boatload of switches. I invite ideas for a bett
er
> way.
>
> Sam
> www.samhoskins.blogspot.com
>
> On Mon, Nov 24, 2008 at 10:23 AM, Robert L. Nuckolls, III <
> nuckolls.bob@cox.net> wrote:
>
> nuckolls.bob@cox.net>
>
> At 08:52 AM 11/24/2008, you wrote:
>
>
> It's not clear how you ended up with so many switches. It's
> axiomatic that the more choices you have for operating switches
> in a tense situation, the less likely that you'll make the
> optimum/right choice. Further, the more switches you have, the
> more likely it is that you'll suffer a switch failure thus
> creating a situation that causes you to take some action.
>
> Can you share the rationale that prompted your departure
> from Z19 suggestions? What value is perceived for splitting
> the ECU controls into two separate switches as opposed to
> single, double pole switches? Have you thought through the
> process(es) you'll exercise when the engine is not running
> quite right? The best Plan-B involves a minimum of activity,
> ideally free of possibilities for doing the wrong thing.
>
> Bob . . .
>
>
> * *
>
> * *
>
> **
>
> **
>
> * -- Please Support Your Lists This Month --*
>
> * (And Get Some AWESOME FREE Gifts!)*
>
> **
>
> * November is the Annual List Fund Raiser. Click on*
>
> * the Contribution link below to find out more about*
>
> * this year's Terrific Free Incentive Gifts!*
>
> **
>
> * List Contribution Web Site:*
>
> **
>
> * --> http://www.matronics.com/contribution*
>
> **
>
> * Thank you for your generous support!*
>
> **
>
> * -Matt Dralle, List Admin.*
>
> **
>
> **
>
> * - The AeroElectric-List Email Forum -*
>
> **
>
> **
>
> **
>
> **
>
> **
>
> * --> http://www.matronics.com/Navigator?AeroElectric-List*
>
> **
>
> **
>
> * - MATRONICS WEB FORUMS -*
>
> **
>
> **
>
> * --> http://forums.matronics.com*
>
> **
>
> **
>
> *
>
===========
===========
===========
============*
>
>
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Another leaking battery |
Yesterday I had the occasion to open the battery compartment on a small audio amplifier
that uses four AA alkaline batteries. All four had leaked and two had
to be pried out. Apple cider vinegar cleaned up the mess with the usual bubbles
normally seen when using baking soda on lead acid battery leaks.
The batteries were purchased at Harbor Freight with Thunderbolt Magnum made in
China on their labels.
I believe we are approaching the point that after using a device powered by batteries,
they must be removed until the next use to prevent problems. I remember
doing this in years gone by.. Earl
Message 3
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: 2-10 SWITCH - Can this be done? |
At 01:23 PM 11/24/2008, you wrote:
>Thanks Bob. Let me cogitate over that a few hours.
>Sam
>
>
>On Mon, Nov 24, 2008 at 1:02 PM, Robert L. Nuckolls, III
><<mailto:nuckolls.bob@cox.net>nuckolls.bob@cox.net> wrote:
><<mailto:nuckolls.bob@cox.net>nuckolls.bob@cox.net>
>
>At 10:53 AM 11/24/2008, you wrote:
>Bob,
>
>Here are my basic thoughts and rational on the design.
>
>The
><<http://www.rotaryaviation.com/eficont.html>http://www.rotaryaviation.com/eficont.html>RWS
>EFI controller (ECU) has two separate Ignition/fuel injection
>controllers mounted on a single board. These are labeled as A &
>B. They are almost identical and separate.
>
>
>They allow separate +12V supply inputs, as well as separate ignition
>and fuel injector output triggers. The two battery busses, main and
>engine, can each supply the A or B sides of the ECU.
>
>
>I am able to select a feed from either the main or the engine
>battery bus and supply it to either the A input of the B input. On
>my drawing, the engine bus is sometimes reffered to as "backup".
Yes, there are MANY combinations of things you can do that
function as advertised. I've seen airplanes at fly-ins that
have LOTS of switches.
Your task as system designer and integrator of components is
to 'optimize' the design. I.e., what components can be eliminated
to reduce complexity from the (1) perspective of reliability and
space savings and (2) reduce pilot workload for having to make
the right decisions for continued flight when some part of the
system decides to throw a temper tantrum.
I'll suggest you reconsider your design with the notion that
(1) the hardware SHARED by plan-a and plan-b systems needs to
be an absolute minimum. (2) Likelihood of having two failures
in the airplane on any single tank full of fuel is exceedingly
rare (read insignificant). (3) Manage energy sources and loads
to meet design goals for endurance when a failure does occur.
I'm certain that you'll discover a way to reduce numbers of
switches down to independent control of system-A and system-B
probably as simple as one switch per system. Does each ECU
have its own dedicated fuel pump or can either pump supply
either system? If the former, combine the pumps on the
ECU controls. If the later, one switch per pump is called for.
Bob . . .
Message 4
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: 2-10 SWITCH - Can this be done? |
Either pump can supply either system. The second EFI pump is just a back-up
to the first.
I think these automotive pumps are very reliable and I won't ever need the
backup unit, but since it keeps the fan turning, it's pretty important to
have the backup.
The fuel system has a bypass-type pressure regulator. When I originally set
this up, I wanted to design it so either pump could be on-line, but not
both, so as not to overload the regulator. That lead to the set-up that
required two switches and an either/or condition. I don't really know the
capacity of the regulator, it just seemed like a good idea.
Instead, I think I will go back to one switch per pump, dedicate them to
main/engine, and arrange the switch bank to better group things together -
make the error proofing visual rather than mechanical.
As you suggested, I am looking into the characteristics of the internally
excited coils and the fuel injectors to see if there is any current draw
when there is no ECU input. My first reaction was to insist that they be
switched, mostly for maintenance purposes. But on second, thought maybe a
panel breaker would do the trick - provided there is no current draw.
Yes, the switch count is coming down.
Sam
On Tue, Nov 25, 2008 at 9:04 AM, Robert L. Nuckolls, III <
nuckolls.bob@cox.net> wrote:
> nuckolls.bob@cox.net>
>
> At 01:23 PM 11/24/2008, you wrote:
>
>> Thanks Bob. Let me cogitate over that a few hours.
>> Sam
>>
>>
>>
>> On Mon, Nov 24, 2008 at 1:02 PM, Robert L. Nuckolls, III <<mailto:
>> nuckolls.bob@cox.net>nuckolls.bob@cox.net> wrote:
>> <<mailto:nuckolls.bob@cox.net>nuckolls.bob@cox.net>
>>
>> At 10:53 AM 11/24/2008, you wrote:
>> Bob,
>>
>> Here are my basic thoughts and rational on the design.
>>
>> The <<http://www.rotaryaviation.com/eficont.html>
>> http://www.rotaryaviation.com/eficont.html>RWS EFI controller (ECU) has
>> two separate Ignition/fuel injection controllers mounted on a single board.
>> These are labeled as A & B. They are almost identical and separate.
>>
>>
>> They allow separate +12V supply inputs, as well as separate ignition and
>> fuel injector output triggers. The two battery busses, main and engine, can
>> each supply the A or B sides of the ECU.
>>
>>
>> I am able to select a feed from either the main or the engine battery bus
>> and supply it to either the A input of the B input. On my drawing, the
>> engine bus is sometimes reffered to as "backup".
>>
>
> Yes, there are MANY combinations of things you can do that
> function as advertised. I've seen airplanes at fly-ins that
> have LOTS of switches.
>
> Your task as system designer and integrator of components is
> to 'optimize' the design. I.e., what components can be eliminated
> to reduce complexity from the (1) perspective of reliability and
> space savings and (2) reduce pilot workload for having to make
> the right decisions for continued flight when some part of the
> system decides to throw a temper tantrum.
>
> I'll suggest you reconsider your design with the notion that
> (1) the hardware SHARED by plan-a and plan-b systems needs to
> be an absolute minimum. (2) Likelihood of having two failures
> in the airplane on any single tank full of fuel is exceedingly
> rare (read insignificant). (3) Manage energy sources and loads
> to meet design goals for endurance when a failure does occur.
>
> I'm certain that you'll discover a way to reduce numbers of
> switches down to independent control of system-A and system-B
> probably as simple as one switch per system. Does each ECU
> have its own dedicated fuel pump or can either pump supply
> either system? If the former, combine the pumps on the
> ECU controls. If the later, one switch per pump is called for.
>
> Bob . . .
>
>
Message 5
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: 2-10 SWITCH - Can this be done? |
Either pump can supply either system. The second EFI pump is just a back-up
to the first.
I think these automotive pumps are very reliable and I won't ever need the
backup unit, but since it keeps the fan turning, it's pretty important to
have the backup.
The fuel system has a bypass-type pressure regulator. When I originally set
this up, I wanted to design it so either pump could be on-line, but not
both, so as not to overload the regulator. That lead to the set-up that
required two switches and an either/or condition. I don't really know the
capacity of the regulator, it just seemed like a good idea.
Instead, I think I will go back to one switch per pump, dedicate them to
main/engine, and arrange the switch bank to better group things together -
make the error proofing visual rather than mechanical.
As you suggested, I am looking into the characteristics of the internally
excited coils and the fuel injectors to see if there is any current draw
when there is no ECU input. My first reaction was to insist that they be
switched, mostly for maintenance purposes. But on second, thought maybe a
panel breaker would do the trick - provided there is no current draw.
Yes, the switch count is coming down.
Sam
www.samhoskins.blogspot.com
On Tue, Nov 25, 2008 at 9:04 AM, Robert L. Nuckolls, III <
nuckolls.bob@cox.net> wrote:
> nuckolls.bob@cox.net>
>
> At 01:23 PM 11/24/2008, you wrote:
>
>> Thanks Bob. Let me cogitate over that a few hours.
>> Sam
>>
>>
>>
>> On Mon, Nov 24, 2008 at 1:02 PM, Robert L. Nuckolls, III <<mailto:
>> nuckolls.bob@cox.net>nuckolls.bob@cox.net> wrote:
>> <<mailto:nuckolls.bob@cox.net>nuckolls.bob@cox.net>
>>
>> At 10:53 AM 11/24/2008, you wrote:
>> Bob,
>>
>> Here are my basic thoughts and rational on the design.
>>
>> The <<http://www.rotaryaviation.com/eficont.html>
>> http://www.rotaryaviation.com/eficont.html>RWS EFI controller (ECU) has
>> two separate Ignition/fuel injection controllers mounted on a single board.
>> These are labeled as A & B. They are almost identical and separate.
>>
>>
>> They allow separate +12V supply inputs, as well as separate ignition and
>> fuel injector output triggers. The two battery busses, main and engine, can
>> each supply the A or B sides of the ECU.
>>
>>
>> I am able to select a feed from either the main or the engine battery bus
>> and supply it to either the A input of the B input. On my drawing, the
>> engine bus is sometimes reffered to as "backup".
>>
>
> Yes, there are MANY combinations of things you can do that
> function as advertised. I've seen airplanes at fly-ins that
> have LOTS of switches.
>
> Your task as system designer and integrator of components is
> to 'optimize' the design. I.e., what components can be eliminated
> to reduce complexity from the (1) perspective of reliability and
> space savings and (2) reduce pilot workload for having to make
> the right decisions for continued flight when some part of the
> system decides to throw a temper tantrum.
>
> I'll suggest you reconsider your design with the notion that
> (1) the hardware SHARED by plan-a and plan-b systems needs to
> be an absolute minimum. (2) Likelihood of having two failures
> in the airplane on any single tank full of fuel is exceedingly
> rare (read insignificant). (3) Manage energy sources and loads
> to meet design goals for endurance when a failure does occur.
>
> I'm certain that you'll discover a way to reduce numbers of
> switches down to independent control of system-A and system-B
> probably as simple as one switch per system. Does each ECU
> have its own dedicated fuel pump or can either pump supply
> either system? If the former, combine the pumps on the
> ECU controls. If the later, one switch per pump is called for.
>
> Bob . . .
>
>
Message 6
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Z13/8 Battery Contactor Failure |
> Obviously many aircraft are wired this way, and presumably, this is an
> unlikely fault, but ...Is there a way to improve on the design ?
Jeff,
Racecars use a mechanical battery switch. The FAA demands a "one-hand operable
battery disconnect and this complies. Even though this may be difficult to arrange
compared to a contactor, it is probably worth the effort. (Google: Flaming
River Battery Switch).
"The problem with the world is that only the intelligent people want to be
smarter, and only the good people want to improve."
- Eolake Stobblehouse
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=216212#216212
Message 7
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Z13/8 Battery Contactor Failure |
At 09:35 PM 11/24/2008, you wrote:
>
>A friend of mine noticed something when looking at my wiring diagram tonight.
>
>If the battery contactor opens in flight, say due to the internal coil
>failing, or the control wiring open circuiting, then the alternator
>will be alive, but without the battery to stabilize the voltage.
When I revise the chapters on alternators and regulators, I'm
going to have to revise advice based on to-long and deeply-held
beliefs that the battery carries a major role in voltage stabilization
for a battery/alternator power system.
There IS a role for the battery but it's a more of a firewall
against (1) system collapse under large transient loads that cause
the alternator to "stall" and (2) mitigation of surge voltage
amplitude during large load dumps. This is pretty easy to
understand:
Consider that a battery needs 14.0 volts or so to take significant
charge. It delivers energy at 12.5 volts and below. So if the bus
is wiggling around between these two values (read alternator
ripple voltage) how much can the battery participate in smoothing
this perturbation? Not much. Battery ability to 'stabilize'
bus perturbations within the bounds of 12.5 to 14.0 volts is
nil.
>That sounds to me like a bad thing. I expect I would know about it
>immediately, due to a buzz in the intercom, but would I (or my wife)
>recognize the fault in time to shut of the main switch before damage
>is done ?
Loss of battery is not a recipe for over-stressed electro-
whizzies . . .
>Will the overvoltage circuitry react well to this scenareo and open
>the field drive soon enough ?
Any source of 3-phase power rectified to produce DC power
has an inherent "ripple" or noise component on the order
of 5% of the DC component. A 14v alternator may be expected
to have a strong ripple voltage of 0.7 volts with lower energy
but higher voltage components consisting of harmonics and diode
switching transients.
The bible for crafting DC power generation systems for vehicles
is Mil-Std-704 which allows 3 volts pk-pk noise on 28v systems,
1.5 volts pk-pk noise on 14v systems. This is allowed because it
is EXPECTED from a normally operating alternator or generator. See
Figure 15 of . . .
http://www.aeroelectric.com/Reference_Docs/Mil-Specs/Mil-Std-704_excerpts.pdf
Okay, take these values a compare them with the battery's ability
to accept or deliver energy. That 1.5 volt, 'window' of compliance
described above is almost exactly the same as an expected pk-pk
noise value delivered by the alternator.
Here's a couple of 'scope traces taken from my dearly departed
Safari van a couple of years ago . . .
http://www.aeroelectric.com/Pictures/Curves/Safari_Bus_Noise_1.gif
http://www.aeroelectric.com/Pictures/Curves/Safari_Bus_Noise_2.gif
The trash on the bus is in keeping with expected performance
of the alternator as a potential noise source and the battery
as a wish-it-were-a-better-filter.
>Obviously many aircraft are wired this way, and presumably, this is an
>unlikely fault, but ...
>Is there a way to improve on the design ?
Doesn't need it. Electro-whizzies for aircraft are EXPECTED
to perform as advertised when powered from systems not unlike
that measured in the traces above and quantified in mil-std-704.
There are certified aircraft (including A36 Bonanza and B58
Baron) that have independent alternator and battery switches.
The alternators on these aircraft will come on line without
benefit of external battery. Further, the noise on the bus
is affected very little by the presence of a battery. Operation
without battery is not prohibited in the AFM.
Short answer: Don't loose any sleep over it.
Bob . . .
Message 8
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Alternator noise |
At 05:13 PM 11/24/2008, you wrote:
>I am getting a lot of what is clearly alternator or voltage
>regulator noise on my radio. (No noise on battery, increasing noise
>in volume and frequency as RPM increases. Radio is a Terra 760D fed
>from the main bus.
>
>I have a small permanent magnet alternator (18 amp John Deere)
>feeding a motorcycle voltage regulator (Crane Fireball), connected
>to the main bus using the B&C relay/overvoltage protection kit which
>already includes a big filter capacitor.
>
>One strange thing I have noticed is that when I turn on the battery,
>the alternator fail light comes on, but when I switch on the
>alternator relay (even with the engine not running), the light goes
>out. Perhaps I wired it incorrectly? Charging seems to work fine.
>
>Anyone had a similar problem and found a fix?
It would be helpful to see your power distribution diagram.
Did you use a z-figure? Can you describe your ground system
to us too?
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 9
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | B&C S700-2-11 switch configuration |
I called B&C and wound up talking to Bill Bainbridge about their S700-2-11
switch configuration. This is listed as ON-ON-OFF. He confessed that he
didn't have any info on it and referred me to Bob.
Is there a link that shows this switch?
Thanks.
Sam
Message 10
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | MaxDim Group Buy Opportunity |
For anyone interested... I have set up a "group buy" for the MaxDim
panel dimmer.
It is ONLY for U.S. members of this Aeroelectric List.
If you are designing/planning your panel or accumulating parts for it...
and there is enough interest (around 6 units or more) I will provide
these for $128 each + shipping (+ sales tax in CA) for a limited time.
These dimmers are unparalleled in performance...
NO heat, NO separate, bulky control unit. NO heatsink. Amazing 350W
power control in a 1.25" diameter unit.
This is a best-of-breed product. Mooney has specified these for all
their new planes! (STC and PMA)
5-35VDC, 12.5Amps and around 2.5 ounces!
Hook up power, ground, and lights (3 connections), 2 mounting holes
to drill, and you're done.
PLEASE CONTACT OFF-LIST psamuelian@charter.net and provide answers
to:
What is your Name?
How many MaxDim units do you want to reserve?
When do you require them?
What is your shipping address? (USA only, please)
What is your phone number?
Please mention the "Aeroelectric MaxDim Group Buy" in the subject of
your email.
Please... FIRM COMMITMENTS ONLY. Treat this as an order.
These are priced a few bucks above distribution to cover the shipping
costs to me, and handling charges when redistributed to you.
I am doing this on a trial basis to see how it goes. If/when we reach
the minimum level I will request payment from you, and place the order.
I recently installed 2 of these in my Cessna and they perform as
advertised.
Thanks!
Phil
RV7 (looking for wing kit), Cessna 177
Message 11
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: 2-10 SWITCH - Can this be done? |
Sam
FWIW there have been several cases of EFI pump failure over the years so
I agree that a backup is a very good idea. On my subaru the fuel
pressure goes up 2 or 3 psi if I run two paralleled pumps
simultaneously. I'm aware of similar reports with other regulators. That
pressure increase is pretty insignificant as far as the engine is
concerned as injector flow varies with the square root of the pressure.
I no longer bother to run two pumps for takeoff and landing but my
switches are laid out such that all engine problems are dealt with by
positioning all switches up with one hand without having to look at
them. A simple emergency procedure like that is well worth some effort
to implement if you can.
The injectors that I'm aware of operate by grounding one side of the
coil through a solid state "transistor". There have been a few cases of
injectors locking on from a shorted "transistor" or wiring. I don't know
if there have been any from the coil shorting internally to ground.
However a locked on injector will not likely be noticed at full power
and maybe not even at cruise power. Definitely noticeable upon power
reduction.
Ken
Sam Hoskins wrote:
> Either pump can supply either system. The second EFI pump is just a back-up
> to the first.
>
> I think these automotive pumps are very reliable and I won't ever need the
> backup unit, but since it keeps the fan turning, it's pretty important to
> have the backup.
>
> The fuel system has a bypass-type pressure regulator. When I originally set
> this up, I wanted to design it so either pump could be on-line, but not
> both, so as not to overload the regulator. That lead to the set-up that
> required two switches and an either/or condition. I don't really know the
> capacity of the regulator, it just seemed like a good idea.
>
> Instead, I think I will go back to one switch per pump, dedicate them to
> main/engine, and arrange the switch bank to better group things together -
> make the error proofing visual rather than mechanical.
>
> As you suggested, I am looking into the characteristics of the internally
> excited coils and the fuel injectors to see if there is any current draw
> when there is no ECU input. My first reaction was to insist that they be
> switched, mostly for maintenance purposes. But on second, thought maybe a
> panel breaker would do the trick - provided there is no current draw.
>
> Yes, the switch count is coming down.
>
> Sam
> www.samhoskins.blogspot.com <http://www.samhoskins.blogspot.com>
>
>
Message 12
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Fast-On Tabs and Soldering |
Chapter 9 of the 'Connection discusses the tradeoffs between soldered and
crimped connections, and suggests that for those who do not want to invest
in crimp-on terminals and associated tools, soldering is acceptable and
possibly preferable for use on airplanes. This chapter goes on to explain
the proper method for soldering and heat-shrinking ring terminals to wire.
However, a solder method for fast-on tabs is not addressed. Since some
electrical components come with male fast-on tabs, it is necessary to
terminate some wires with female fast-on tabs. Do I still need to invest in
the crimp-on terminals and associated tools to do fast-on tabs, or is there
a method and terminal type for soldering fast-on tabs as well, and if so, is
there any documentation on this?
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|