Today's Message Index:
----------------------
1. 04:09 AM - FAA style harness (Fergus Kyle)
2. 05:30 AM - Re: High Current Switch or Battery Contactor (Gary Casey)
3. 06:01 AM - Re: Re: High Current Switch or Battery (Robert L. Nuckolls, III)
4. 06:03 AM - OBAM Regulations ()
5. 06:07 AM - Re: High Current Switch or Battery Contactor (Robert L. Nuckolls, III)
6. 08:13 AM - Re: FAA style harness (Matt Prather)
7. 08:23 AM - Re: OBAM Regulations (SportAV8R@aol.com)
8. 08:41 AM - Genave Alpha 200B Radio wiring schematic (Jim Ellsworth)
9. 11:16 AM - Re: Genave Alpha 200B Radio wiring schematic (Fred Fillinger)
10. 05:50 PM - Re: E-Bus Usage Procedure / Question (Robert L. Nuckolls, III)
11. 07:14 PM - EXP BUS 2V idea - what do you think? (Brian Sowell Home)
12. 09:59 PM - Re: EXP BUS 2V idea - what do you think? (James E. Clark)
Message 1
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| Subject: | FAA style harness |
--> AeroElectric-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
Hi,
I have no expertise in this topic, certainly not Ira's - but
having dusted off the brain case, wish to feed an idea or two into the fray.
My tired brain is addicted to the few split seconds of potential
damage during a prang involving excessive G. Having learnt of Graham's
experience (and the apparent difference in injuries 'twixt him and other
occupant), repeat trhe suggestion that those foam 'worms' may have had a
beneficial effect. Also, I wonder at the dispersion/deflection of a sealed
airbag [not explosive] during that deceleration.
There is not much space available for deceleration at a controlled
rate (cars and some aircraft presumably utilise this) but any experience I
have leads me to believe that any/all design directed toward this end would
have a measureable effect during those few inches of travel.
Certainly the angle of tether of the shoulder straps must be
revised, but attaching the tether to the aircraft too far back leads to
thoughts of greater harm from fuselage distortion - i.e: tethering to the
tail might sting if that portion separated {as this has been successfully
experienced early on].
I just don't like to 'waste' those precious inches on uncontrolled
collapse.
My $.02.
Ferg
Message 2
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| Subject: | Re: High Current Switch or Battery Contactor |
--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
<<Here's an idea for those of you trying to keep current within a small
>budget. Instead of using a battery contactor, why not use a high current
>switch like this one:>>
I've been thinking about the same thing and there is one failure mode that
bothers me: Let's say that in flight you need to shut off the master bus,
so you turn off the manual switch. Oops, the alternator and voltage
regulator are connected "downstream" of the master switch and hence keep
right on working, keeping the master bus live. You have to disconnect the
alternator (at least the regulator) to shut the system off. The
conventional split master switch/contactor combination won't let you shut
off the master without also shutting off the alternator. So with a manual
switch the procedure has to be to pull the alternator breaker(s) and then
turn off the battery. Does this change the desirability of the manual
switch? I'm not sure.
Gary Casey
Message 3
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| Subject: | Re: High Current Switch or Battery |
Contactor
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Contactor
At 05:17 AM 12/8/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
>
><<Here's an idea for those of you trying to keep current within a small
> >budget. Instead of using a battery contactor, why not use a high current
> >switch like this one:>>
>
>I've been thinking about the same thing and there is one failure mode that
>bothers me: Let's say that in flight you need to shut off the master bus,
>so you turn off the manual switch. Oops, the alternator and voltage
>regulator are connected "downstream" of the master switch and hence keep
>right on working, keeping the master bus live. You have to disconnect the
>alternator (at least the regulator) to shut the system off. The
>conventional split master switch/contactor combination won't let you shut
>off the master without also shutting off the alternator. So with a manual
>switch the procedure has to be to pull the alternator breaker(s) and then
>turn off the battery. Does this change the desirability of the manual
>switch? I'm not sure.
Only from the perspective of reducing pilot workload. There are
LOTS of procedures for doing things that suggest a serial list
of activities for pullilng levers and twisting knobs.
The combined battery and alternator control on the DC power
master switch works toward workload reduction and risk mitigation.
I've kept the recommendation for the el-cheapo, RPM/WhiteRogers/Stancore
contactors in my writings because they are an excellent value.
Their track record goes back to the 1940's on the C-140, C-170 when
batteries and generators went in for the first times. They're
not the best contactor you can buy but use within their
well-known limitations, they've demonstrated their capabilities
quite dramatically.
If one designs for failure tolerance, the occasional loss of
a contactor is no big deal and it's power drain is insignificant
any time a capable alternator is running. It seems that any
efforts to eliminate the device are more a matter of personal
preferences than for system gains based on simple-ideas. Personally,
I'd use the contactor on any aircraft that is not power-starved
in normal operations. This condition generally includes all
aircraft not powered by a PM alternator.
Bob . . .
Message 4
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| Subject: | OBAM Regulations |
--> AeroElectric-List message posted by: <bakerocb@cox.net>
AeroElectric-List message previously posted by: "Robert L. Nuckolls, III"
<b.nuckolls@cox.net>
<<....skip....There are no regulations that pertain to the design and
installation of any system in your OBAM aircraft. Bob . . .>>
12/08/2004
Hello Bob Nuckolls, There are some exceptions to your statement above. Those
exceptions should be recognized lest some builder be led astray. The
exceptions usually deal with items that must interface correctly with
outside equipment or are specifically safety oriented. Some items that come
to mind that apply to OBAM aircraft, as well as standard type certificated
aircraft, are:
(1) Transponders installed in OBAM aircraft (amateur built experimental
aircraft) must meet the certification requirements of FAR Sec 91.215.
Periodic inspection criteria of the transponder (and altimeter of aircraft
flown IFR) also apply to OBAM aircraft.
(2) FAR Sec 91.207 requires that Emergency Locator Transmitters (ELT's)
installed in OBAM aircraft must be "approved" in some fashion. Normal
current approval method would be by TSO-C91a.
(3) FAR Sec 91.205 (c) (2) requires that position lights installed on OBAM
aircraft be "appproved". This approval could be granted by the inspector who
makes the initial airworthiness inspection of the OBAM aircraft. The
inspector could logically use the position light criteria set forth for
standard type certificated aircraft in FAR Secs 23.1387 through 23.1397.
(4) FAR Sec 91.205 (c) (3) requires that the anti collision light system
installed on OBAM aircraft be "approved". This approval could be granted by
the inspector who makes the initial airworthiness inspection of the OBAM
aircraft. The inspector could logically use the position light criteria set
forth for standard type certificated aircraft in FAR Sec 23.1401.
(5) FAR Secs 91.205 (13) and (14) require that the OBAM aircraft be equipped
with "approved" safety belts (lap restraints) and shoulder harnesses. This
approval could be granted by the inspector who makes the initial
airworthiness inspection of the OBAM aircraft. Since there is no
certification requirement for OBAM aircraft in this regard it is not
required that the belts be approved and marked through a TSO process. (Some
inspectors mistakenly try to insist on TSO marked belts and harnesses.)
(6) FAR Sec 91.205 (c) (6) says that if the OBAM builder builds his aircraft
so that he has access to his electrical fuses while in flight that he must
have one spare set of fuses, or three spare fuses of each kind that are
required.
(7) FAR Sec 91.205 lists, in general, the equipment that an OBAM aircraft
must have, but does not require this equipment to be approved.
There may be some other regulatory "gotchas" that relate to OBAM aircraft
(such as "approved" DME in certain circumstances), but those above are what
come to mind. My point is that it behooves our builders and operators to
know what the regulatory requirements are and not make the blanket
assumption that regulations do not apply to our OBAM aircraft and their
operations.
OC
Message 5
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| Subject: | Re: High Current Switch or Battery Contactor |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 07:10 PM 12/7/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: Denis Walsh <denis.walsh@comcast.net>
>
>I have been pondering this for years. My contactor uses the better
>part of an amp, not to mention another fail mode. A few years ago I
>saw something very like this on a Mooney so it is or was ok back then
>with FAA. It was operated by a cable and lever.
A Tri-Pacer I flew in 1961 had the battery under the co-pilot's
seat. The battery master was a high current switch on the forward
side of the bulkhead under the co-pilot's knees.
>The biggest down side I see is that it needs to be very close to the
>battery for crash safety purposes. If you do this, then you need a
>cable or lever to remotely operate it. This introduces what is
>probably a bigger failure probability, and weight issues too.
The manually operated switch can generally be implemented
for about the same weight as a contactor unless the control
cable is VERY long.
>So in the end, since the ones I found were just as heavy as the
>solenoid, I stayed with the solenoid, which I think gets the nod on
>parts count and simplicity for remote operation.
>
>Post script. The only time the solenoid load is an issue for me is
>when the alternator fails. In that case, the master contactor goes off
>anyway and its function is replace with a low or no drain relay/switch.
> Also it is a very reliable device, and lasts a long time, unlike its
>starter contactor brethren, which gets heavier wear in use.
>
>Interested in hearing other slants on this.
You're perceptions and deductions are, in my opinion,
quite accurate.
Bob . . .
Message 6
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| Subject: | Re: FAA style harness |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
Interesting that you should mention this... Recently, a fellow I know
(not closely) was involved in a crash of an Extra 300L - bottom of loop
just slightly too low. The force of the impact caused the fuselage structure
to be severed just behind the pilot's (back) seat. However, apparently, the
shoulder harness are attached to the tail section. (!) Though this fellow
survived (lucky), he was pretty beat up from having the load of the severed
tail section pulling down on his back and shoulders as the aircraft tumbled
across the desert. It is indeed important to be sure that whateveryou tie
the seatbelts to is designed to stay with the seat.
Regards,
Matt-
> --> AeroElectric-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
>
> Hi,
> I have no expertise in this topic, certainly not Ira's - but
> having dusted off the brain case, wish to feed an idea or two into the
> Certainly the angle of tether of the shoulder straps must be
> revised, but attaching the tether to the aircraft too far back leads to
> thoughts of greater harm from fuselage distortion - i.e: tethering to
> the tail might sting if that portion separated {as this has been
> successfully experienced early on].
> I just don't like to 'waste' those precious inches on
> uncontrolled
> collapse.
> My $.02.
> Ferg
>
>
Message 7
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| Subject: | Re: OBAM Regulations |
--> AeroElectric-List message posted by: SportAV8R@aol.com
Now we can expect a flurry of questions for Bob about wiring our seatbelts per
the Z-diagrams...??
do not archive
>>>(5) FAR Secs 91.205 (13) and (14) require that the OBAM aircraft be equipped
with "approved" safety belts (lap restraints) and shoulder harnesses. This
approval could be granted by the inspector who makes the initial
airworthiness inspection of the OBAM aircraft. Since there is no
certification requirement for OBAM aircraft in this regard it is not
required that the belts be approved and marked through a TSO process. (Some
inspectors mistakenly try to insist on TSO marked belts and harnesses.)<<<
Message 8
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| Subject: | Genave Alpha 200B Radio wiring schematic |
--> AeroElectric-List message posted by: "Jim Ellsworth" <ellsworj@m33access.com>
I have on old Genave Alpha 200B radio I would like to hook up in my hanger
and need the wiring layout of the 12 pin plug.
I need to know what terminals are for power, speaker, mic, etc. Any help
would be appreciated.
Thanks
Jim Ellsworth
RV7A wings
ellsworj@m33access.com
Message 9
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| Subject: | Re: Genave Alpha 200B Radio wiring schematic |
--> AeroElectric-List message posted by: "Fred Fillinger" <n3eu@comcast.net>
Jim Ellsworth wrote:
>
> I have on old Genave Alpha 200B radio I would like to hook up in
> my hanger and need the wiring layout of the 12 pin plug.
>
> I need to know what terminals are for power, speaker, mic, etc. Any
> help would be appreciated.
The Alpha 200A is as follows; 200B likely the same:
1 - 14VDC
4 - Mic key
5 - Mic audio
9 - Speaker audio
11 - Phone audio
12 - Ground
Note also, that the nav antenna is used for Comm receive. The comm
antenna jack is for xmit only.
Reg,
Fred F.
Message 10
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| Subject: | Re: E-Bus Usage Procedure / Question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 09:43 AM 12/5/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Dan Checkoway" <dan@rvproject.com>
>
> > That is correct. But, The voltage drop across the diode should not affect
>the items
> > that are being powered by the e- buss.
>
>Do you mean to say the 0.7V drop won't cause a *noticeable* affect -- i.e.
>the avionics won't perform any differently? I agree with that, but one
>thing that I do notice is a 0.2 to 0.3A difference on my hall effect driven
>ammeter when I switch the E-Bus on and off in flight.
>
>If I can save my alternator from having to producing that extra quarter of
>an amp, it's a minor victory. ;-)
Consider that when the alternator is running, the bus voltage is not
less than 13.8 and maybe as high as 14.5 volts. Subtract a diode drop
of as high as 1 volt and you have 12.8 or MORE on the e-bus.
When the alternator quits, and you're operating battery only, we expect
things on the e-bus to operate well . . . in fact, it's a design goal
for electro-whizzies for aircraft to function to the intended task over
a range of 11-15 volts. A battery delivers energy over the range of 11-12.7
volts or so.
So, in spite of the potential for loss of as much as 1.0 volts in an
e-bus isolation diode, performance of goodies on the e-bus should
not be affected in any significant way. Yes, a comm transmitter's power
output may be reduced by 10% but nobody at the far end will know the
difference.
So the answer is, "No, the diode voltage drop is not significant
in terms of how well accessories on the e-bus function."
Bob . . .
Message 11
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| Subject: | EXP BUS 2V idea - what do you think? |
--> AeroElectric-List message posted by: "Brian Sowell Home" <bsowell@digitex.net>
In order to use the Keep Alive and Clearance Delivery features of the
EXP BUS 2V, AND use a firewall mounted Master Contactor to be able to
swtich off the #8 AWG Main Battery lead running into the cockpit, I'm
considering doing the following. Please tell me what you think.
Desired State:
I want to use the Keep Alive terminal to power my Dynon EFIS so that
internal battery stays charged and the clock stays current, and
I want to use the Keep Alive terminal to power the Clearance Delivery
feature so I can use my comm intercom & music system with the master
off.
I want the large #8 wire running into my cockpit to the EXP BUS to be
switched off for safety reasons.
Everything is installed, so going back and making big changes is not
desireable. I want the solution to be simple to install.
I'm currently using the 40-amp-rated master relay on the EXP BUS with
the battery lead coming directly from the battery (no master
contactor, fuse, or any other protection). I have a firewall mounted
Master Contactor installed that is currently only supplying power to
the starter through the starter contactor. I installed the master
contactor 'just in case I need it someday', and to allow me to swtich
off the starter if the starter relay got stuck closed. When I close
the master switch, both the 40 amp EXP BUS relay, and the Master
Contactor close.
Proposed Solution:
Move the EXP BUS battery lead to the switched side of the firewall
mounted Master Contactor. Normally this would switch the EXP BUS off
completely when the master is off, disabling the Keep Alive and the
Clearance Delivery features.
But, if I also install a fuse, fuseable link, or other (say, 10 amp
protection) between the two terminals on the master contactor, then
the EXP BUS could draw up to 10 amps through the main battery lead
through this fuse. If a short occurred in the main battery lead with
the master off, the fuse would protect it.
Discussion:
Since the EXP BUS Master relay opens when the firewall mounted master
contactor opens (they're on the same switch), then the only way the
the EXP BUS could continue to draw through this 10 amp 'short
circuit' is through the keep alive feature which is limited by a 3
amp polyfuse, and the #6 avionics bus connector (for comm and
intercomm) which is limited by a 7 amp polyfuse.
The only down side I can see with this is that the EXP BUS now has
both the master contactor and the 40 amp master relay through which
to draw power. It would work fine, but not a good idea from a
reliability standpoint. However, I do not have any critical systems
on the EXP BUS. If one of these fail, my dynon has a battery backup,
as does my GPS. My comm and intercom could be turned on using the
Clearance Delivery feature. I would lose my lights, my engine
instruments, and my transponder.
Any downside I'm not seeing?
Brian
Message 12
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| Subject: | EXP BUS 2V idea - what do you think? |
--> AeroElectric-List message posted by: "James E. Clark" <james@nextupventures.com>
Brian,
We have an EXP-BUS installation with similar functionality but a slightly
different approach.
<Your approach will probably do fine ... not trying to "analyze that" ...
just going to share what I did.>
** You probably are most aware of all of what I am about to say so no insult
intended. There may be others just starting to sort out what they might do.
**
CV points out that there is an option to *remove* their little relay and use
an external contactor. It involves soldering a good size wire across to
points and pulling out the little relay. The EXP Bus is then feed by your
switched contactor (presumbably mounted on the engine side of the firewall).
1. I made this change.
Next, I decided that I wanted the rightmost three switches to serve "kinda
like" an "E-bus". Bear with me as I am a bit liberal with my definition
here. The three switches control a) autopilot, b) AUX DC power and c)
"Clearance Delivery
I make the assumption that if I have to switch OFF the EXP BUS (for whatever
reason) and I am "over the mountains in the middle of the night and it is
IFR, blah, blah" (yeah, I am exaggerating a bit) there are a couple of
things that would be nice to be able to power. Namely the autopilot to keep
the wings level, DC power for maybe a little light and in case the "fresh"
batteries in the handheld GPS are dead and the COM radio (with intercom). I
should be able to make it home with that. :-) The Jeff Rose Electronic
ignition used to be "hard wired" but he suggested having a switch so the
power could be turned off separately from the "mag switch" and thus does not
enter the EXP BUS equation. That switch is used to power the autopilot.
2. TO accomplish this I fed the BBAT circuit (I think) with power in a
manner somewhat as you describe. It is taken DIRECTLY from the battery with
protection via a small fuseblock on the ENGINE side of the firewall. I wired
BBAT this way as well so that later if for some reason I chose, a small
"backup battery" could be put under the cowl and it supply power. But for
now the BBAT lead is tied to the "pain ole BAT".
This approach has worked fine for over 400 hours now in two years.
Don't have my drawings before me or I would bemore specific and comment on
your specifics.
I gues the only thing that I did that was REALLY different from what you
propose is to bite the bullet and make their changeover to a heavy duty
contactor via the big "jumper".
James
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