Today's Message Index:
----------------------
1. 05:10 AM - Re: sanity check (Jack Lockamy)
2. 06:20 AM - Manual battery contactor (Gordon Robertson)
3. 06:22 AM - Fuel pressure warning light (Gary Casey)
4. 08:26 AM - Re: cell phone antenna (richard@riley.net)
5. 10:18 AM - Re: Fuel pressure warning light (Robert L. Nuckolls, III)
6. 10:54 AM - Re: current flow (Robert L. Nuckolls, III)
7. 10:55 AM - circuit breaker buss bar (Jim Lane)
8. 11:35 AM - Re: circuit breaker buss bar (Charlie & Tupper England)
9. 01:04 PM - Re: cell phone antenna (Brian Lloyd)
10. 01:29 PM - Re: Fuel pressure warning light (klehman@albedo.net)
11. 02:24 PM - Re: circuit breaker buss bar (Robert L. Nuckolls, III)
12. 07:17 PM - Panel Drawing (Emrath)
Message 1
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| Subject: | Re: sanity check |
--> AeroElectric-List message posted by: "Jack Lockamy" <jacklockamy@att.net>
Dan,
I too have a FUEL PUMP ON annunicator light in my panel. The annunciator is only
a reminder to turn the electric boost pump after take-off. I wired the 12v
light off the same circuit/fuse as the fuel pump. If the light bulb burns out,
the fuel pump should not be affected. I simply 'pigtailed' off the (+) lead
of the fuel pump circuit.
I agree with your buddy.... adding a relay complicates things.
Someone please correct me if I'm wrong.
Jack Lockamy
Camarillo, CA
RV-7A
DO NOT ARCHIVE
Message 2
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| Subject: | Manual battery contactor |
--> AeroElectric-List message posted by: "Gordon Robertson" <grobertson@verizon.net>
>>The negative terminal is called that because electrons are negatively
charged,
>>and it has the excess. The positive terminal lacks electrons, and seeks
them.
This is always confusing to the non-electrical engineer. It comes about
because before folks recognized that current was a flow of electrons, and
were experimenting with batteries, they just picked one battery terminal as
*positive* and one as *negative*. Could easily have picked it the other
way around. Unfortunately, when they realized that the electrons actually
flowed the other way from what they had picked, the only solution was to
define the electron charge as negative. Everything else follows from that
single unfortunate guess.
Gordon Robertson
RV8- waiting for engine
Message 3
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| Subject: | Fuel pressure warning light |
--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
All this talk about electric pump operating lights prompts me to get
comments on an idea I had: Put a pressure switch in the line between the
mechanical pump and the carburetor or injector servo. When the fuel
pressure drops below the switch point a latching relay is energized, turning
on the electric pump. Of course, as soon as the electric pump starts
delivering pressure the switch will turn back off, but the latching relay
will keep the pump on. The hold circuit to the latching relay can be
interrupted with the fuel pump switch, which would be of the on-off-on
variety, one of the on positions being the "automatic" setting and the other
a positive on. On master-on, turn the switch to the auto position,
verifying that the pump turns on and stays on, then turn it off to shut it
off for engine starting (just to reduce battery draw during cranking). Then
turn it back to the auto position for the flight. The relay would also turn
on an "electric pump operating" light, as otherwise there would be no way to
know if the mechanical pump failed during flight. I think the extra
complexity is worth it as it removes the pilot from a critical failure mode
scenario. To assume the pilot will always remember to turn on the electric
pump in case a sudden silence is a false assumption. My partner experienced
just such a silence and he never tried the electric pump - in this case it
wouldn't have done any good anyway, but the point remains that to rely on
human performance in an emergency is a weak design philosophy.
Gary Casey
Message 4
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| Subject: | Re: cell phone antenna |
--> AeroElectric-List message posted by: richard@riley.net
At 12:20 PM 4/23/04 -0500, you wrote:
>--> AeroElectric-List message posted by: jerb <ulflyer@verizon.net>
>
>It's is still illegal today as far as I know - you'll need an Air-Phone if
>you want to have legal phone service while airborne or maybe one of them
>Iridium satellite jobs.
>jerb.
Here's the memo I wrote for work, use at your own risk, I'm not a lawyer,
your mileage may vary, etc.
----------
The use of cellular telephones in airplanes is regulated by both the FCC
and the FAA. The applicable code sections are:
FCC: Sec. 22.925 Subpart H Cellular Radiotelephone Service
Prohibition on airborne operation of cellular telephones.
Cellular telephones installed in or carried aboard airplanes, balloons or
any other type of aircraft must not be operated while such aircraft are
airborne (not touching the ground). When any aircraft leaves the ground,
all cellular telephones on board that aircraft must be turned off. The
following notice must be posted on or near each cellular telephone
installed in any aircraft: ``The use of cellular telephones while this
aircraft is airborne is prohibited by FCC rules, and the violation of this
rule could result in suspension of service and/or a fine. The use
of cellular telephones while this aircraft is on the ground is subject to
FAA regulations.
There is an exception made specifically for "Air Cell" service, and I have
a bunch of supporting material on that. Basically, It uses AMPS
frequencies and (modified) AMPS equipment (including FCC-definition
"cellular telephones"). Power output is reduced and horizontally-polarized
antennas are used. The license is limited both in extent (it can only
support a couple of hundred users nationwide at any one time) and duration
(it's being renewed a couple of years at a time.)
The FAA supports this rule with FARs 91.21, 121.306, and 135.144
(Portable electronic devices.) The three sections are identical, 91
applies to general aviation, 121 to airlines and 135 to commuters. The 121
section reads:
Sec. 121.306 Portable electronic devices.
(a) Except as provided in paragraph (b) of this section, no person may
operate, nor may any operator or pilot in command of an aircraft allow the
operation of, any portable electronic device on any U.S.-registered civil
aircraft operating under this part.
(b) Paragraph (a) of this section does not apply to--
(1) Portable voice recorders;
(2) Hearing aids;
(3) Heart pacemakers;
(4) Electric shavers; or
(5) Any other portable electronic device that the part 119 certificate
holder has determined will not cause interference with the navigation or
communication system of the aircraft on which it is to be used.
In addition to the regulation we also have an Advisory Circular that
explains all this for general aviation. It's AC 91.21-1A (Use of Portable
Electronic Devices Aboard Aircraft). Ive included it at the end of this
message. An AC does not carry the authority of a regulation - it's
recommendations on how to comply with an underlying regulation. And in
this case, the three FAR sections includes an exception for all portable
electronic devices that (b)5 the part 119 certificate holder has determined
will not cause interference with the navigation or communication system of
the aircraft on which it is to be used.
Here's where it gets interesting.
According to the FCC, "cellular telephone" only refers to equipment
operating under Part 22. This includes not only analog (AMPS) equipment
but also digital service that AMPS providers provide. AMPS providers have
been authorized to provide digital service on the same frequencies
(824-849/869-894 MHz) under a blanket authorization that only requires that
they continue to provide AMPS service for some unknown period.
Per my conversation with Mike Ferrante of the FCC's Wireless
Telecommunications Bureau Enforcement Division last year, PCS is a whole
different ballgame. There is no airborne use restriction (from the FCC) on
PCS. The FCC has allocated 25MHz to PCS and the industry is free to allow
all or part of that to be used by airborne customers. Narrowband PCS
operates 901-902 MHz, 930-931 MHz, and 940-941 MHz. PCS is covered under
Part 24 of the FCC regulations, which dont mention airplanes or airborne
use at all. FAA regulations and advisory circulars do not address
PCS. They only refer to cellular telephones (like AC 91.21-1A 7ii)
Therefore, under FAR 121.306 paragraph B5, if a part 119 or part 91
certificate holder wants to permit the use of PCS phones in their aircraft,
they are authorized to determine that the PCS phones don't interfere with
communications or navigation, and proceed.
USE OF PORTABLE ELECTRONIC
AC No: 91.21-1A
DEVICES ABOARD AIRCRAFT
Initiated by: AFS-330
Change:
1. PURPOSE.
This advisory circular (AC) provides aircraft operators with information
and guidance for assistance in compliance to Title 14 of the Code of
Federal Regulations (14 CFR) part 91, section 91.21. Section 91.21 was
established because of the potential for portable electronic devices (PED)
to interfere with aircraft communications and navigation equipment. It
prohibits the operation of PED's aboard U.S.-registered civil aircraft,
operated by the holder of an air carrier operating certificate, an
operating certificate, or any other aircraft while operating under
instrument flight rules (IFR). This rule permits use of specified PED's and
other devices that the operator of the aircraft has determined will not
interfere with the safe operation of the aircraft in which it is operated.
The recommendations contained herein are one means,
but not the only means, of complying with section 91.21 requirements,
pertaining to the operation of PED's.
2.
CANCELLATION.
AC 91.21-1, Use of Portable Electronic Devices Aboard Aircraft, dated
August 20, 1993, is canceled.
3.
RELATED 14 CFR SECTIONS.
Section 91.21, 121.306, 125.204, and 135.144.
4.
BACKGROUND.
Section 91.21 (formerly 91.19) was initially established in May 1961 to
prohibit the operation of portable frequency-modulated radio receivers
aboard U.S. air carrier and U.S.-registered aircraft when the very high
frequency omnidirectional range was being used for navigation purposes. The
Federal Aviation Administration (FAA) subsequently determined that other
PED's could be potentially hazardous to aircraft communication and
navigation equipment, if operated aboard aircraft. Amendment 91-35 amended
the scope of former section 91.19 to prohibit the use of additional PED's
aboard certain U.S. civil aircraft. Earlier studies conducted by RTCA, Inc.
(RTCA), Special Committee 156, Document No. RTCA/DO-199, Volumes 1 and 2,
entitled "Potential Interference to Aircraft Electronic Equipment from
Devices Carried Aboard," have contributed greatly to an understanding of
the operational effects of PED's aboard aircraft.
(See paragraph 7b for obtaining copies.)
5.
DISCUSSION.
Section 91.21 allows for the operation of PED's which the operator of the
aircraft has determined will not interfere with the navigation or
communication system of that aircraft. The determination of the effect of a
particular device on the navigation and communication system of the
aircraft on which it is to be used or operated must, in case of an aircraft
operated by the holder of an air carrier certificate or other operating
certificate, be made by that operator (i.e., certificate holder). In all
other cases, a determination must be made and it may be made by the
operator and/or the pilot-in-command (PIC). In some cases, the
determination may be based on operational tests conducted by the operator
without sophisticated testing equipment. When safely at cruise altitude,
the pilot could allow the devices to be operated. If interference is
experienced, the types of devices causing interference could be isolated,
along with the applicable conditions recorded. The device responsible for
the interference should then be turned off. If all operators collect this
type of data with specific information, a large enough database could be
generated to identify specific devices
Page 2
10/02/00
AC 91.21-1A
Page 2
Par 5
causing interference. The operator may elect to obtain the services of a
person or facility having the capability of making the determination for
the particular electronic device and aircraft concerned. The rule as
adopted was drafted to require the air carrier or commercial operator to
determine whether a particular PED will cause interference when operated
aboard its aircraft. Personnel specifically designated by the air carrier
or commercial operator for this purpose may make this determination. For
other aircraft, the language of the rule expressly permits the
determination to be made by the PIC or operators of the aircraft. Thus, in
the case of rental aircraft, the renter-pilot, lessee, or owner-operator
could make the determination.
6.
RECOMMENDED PROCEDURES FOR THE OPERATION OF PED's ABOARD AIRCRAFT.
a.
If an operator allows the use of PED's aboard its aircraft, procedures
should be established and spelled out clearly to control their use during
passenger-carrying operations. The procedures, when used in conjunction
with an operator's program, should provide the following:
(1) Methods to inform passengers of permissible times, conditions, and
limitations when various PED's may be used. This may be accomplished
through the departure briefing, passenger information cards, captain's
announcement, and other methods deemed appropriate by the operator. The
limitations, as a minimum, should state that use of all such devices
(except certain inaccessible medical electronic devices, such as
pacemakers) are prohibited during any phase of operation when their use
could interfere with the communication or navigation equipment on board the
aircraft or the ability of the flightcrew to give necessary instructions in
the event of an emergency.
(2) Procedures to terminate the operation of PED's suspected of causing
interference with aircraft systems.
(3) Procedures for reporting instances of suspected and confirmed
interferences by a PED to the local FAA Flight Standards District Office.
(4) Cockpit to cabin coordination and cockpit flightcrew monitoring procedures.
(5) Procedures for determining acceptability of those portable electronic
components to be operated aboard its aircraft. The operator of the aircraft
must make the determination of the effects of a particular PED on the
navigation and communication systems of the aircraft on which it is to be
operated. The operation of a PED is prohibited, unless the device is
specifically listed in section 91.21(b) (1) through (4). But, even if the
device is specifically accepted from the general prohibition on the use of
PED's, an operator may prohibit use of that PED. The use of all other PED's
is prohibited by regulation, unless pursuant to section 91.21(b)(5). The
operator determines that the operation of that device will not interfere
with the communication or navigation system of the aircraft on which it is
to be operated.
(6) Prohibiting the operation of any PED's during the takeoff and landing
phases of flight. It must be recognized that the potential for personal
injury to passengers is a paramount consideration as well as the
possibility of missing important safety announcements during these
important phases of flight. This is in addition to lessening the possible
interference that may arise during sterile cockpit operations (below 10,000
feet).
Page 3
AC 91.21-1A
10/02/00
Par 6
Page 3
(7) Prohibiting the operation of any PED's aboard aircraft, unless
otherwise authorized, which are classified as intentional radiators or
transmitters. These devices include, but are not limited to:
(i) Citizens band radios.
(ii) Cellular telephones.
(iii) Remote control devices.
b.
PED's designed to transmit have consideration in addition to paragraph 6a.
There are certain devices, which by their nature and design, transmit
intentionally. These include cellular telephones, citizens band radios,
remote control devices, etc. The Federal Communications Commission (FCC)
typically licenses these devices as land mobile devices. The FCC currently
prohibits the use and operation of cellular telephones while airborne. Its
primary concern is that a cellular telephone, while used airborne, would
have a much greater transmitting range than a land mobile unit. This could
result in serious interference to transmissions at other cell locations
since the system uses the same frequency several times within a market.
Since a cellular mobile telephone unit is capable of operating on all
assignable cellular frequencies, serious interference may also occur to
cellular systems in adjacent markets. The FAA supports this airborne
restriction for reasons of potential interference to critical aircraft
systems. Currently, the FAA does not prohibit use of cellular telephones in
aircraft while on the ground if the operator has determined that they will
not interfere with the navigation or communication system of the aircraft
on which they are to be used. An example might be their use at the gate or
during an extended wait on the ground, while awaiting a gate, when
specifically authorized by the captain. A cellular telephone will not be
authorized for use while the aircraft is being taxied for departure after
leaving the gate. The unit will be turned off and properly stowed,
otherwise it is possible that a signal from a ground cell could activate
it. Whatever procedures an operator elects to adopt should be clearly
spelled out in oral departure briefings and by written material provided to
each passenger to avoid passenger confusion.
c.
Telephones, which have been permanently installed in the aircraft, are
licensed as air-ground radiotelephone service frequencies. In addition,
they are installed and tested in accordance with the appropriate
certification and airworthiness standards. These devices are not considered
PED's provided they have been installed and tested by an FAA-approved
repair station or an air carrier's-approved maintenance organization and
are licensed by the FCC as air-ground units.
7.
MANUFACTURERS' TEST CRITERIA FOR PED's.
a.
Operators should use manufacturers' information, when provided, with each
device that informs the consumer of the conditions and limitations
associated with its use aboard aircraft.
b.
All portable electronic devices should be designed and tested in accordance
with appropriate emission control standards. Document Nos. RTCA/DO-160D,
Environmental Conditions and Test Procedures for Airborne Equipment, and
RTCA/DO-199, may constitute one acceptable method for meeting these
requirements. These documents may be purchased from: RTCA Secretariat, 1140
Connecticut Avenue, NW, Suite 1020, Washington, DC 20036.
c.
Medical-Portable Electronic Devices (M-PED), such as automated external
defibrillators (AED), airborne patient medical telemonitoring (APMT)
equipment, etc., should be designed and tested in accordance with Section
21, Category M, of RTCA document No. RTCA/DO-160D. M-PED's that test within
the emission levels contained in this document, in all modes of operation
(i.e., standby, monitor, and/or transient operating conditions, as
appropriate), may be used onboard the aircraft without any further testing
by the operator. Equipment tested and found to exceed the Section 21,
Category M, emission levels are required to
Page 4
10/02/00
AC 91.21-1A
Page 4
Par 7
be evaluated in the operator's M-PED selected model aircraft for
electromagnetic interference (EMI) and radio frequency interference (RFI).
All navigation, communication, engine, and flight control systems will be
operating in the selected aircraft. The ground EMI/RFI evaluation should be
conducted with the M-PED equipment operating, and at the various locations
in the cabin where M-PED usage is expected (galley, passenger aisles,
etc.). If M-PED equipment can be operated at any location in the cabin,
then the worst-case locations (proximity to cable bundles, flight controls,
electronic and electrical bays, antennas, etc.) should be considered. Air
carriers planning to equip their aircraft with M-PED's will provide
evidence to the principal FAA inspector that the M-PED equipment meets the
RTCA/DO-160D Section 21, Category M, emission levels, or conducts the
ground EMI/RFI evaluation described above. Operators will incorporate
procedures into their maintenance program to determine the M-PED's
serviceability based on the equipment manufacturers' recommendations, to
include procedures for marking the date of the equipment's last inspection.
Operators will establish operational procedures that require crewmembers to
inform the PIC when the M-PED is removed from its storage for use.
NOTE: For those M-PED's using Lithium Sulfur Dioxide batteries (LiSO
2) as a power source, the batteries must be Technical Standard Order C-97
(TSO-C97) approved and labeled accordingly.
/s/
L. Nicholas Lacey
Director, Flight Standards Service
Message 5
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| Subject: | Re: Fuel pressure warning light |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 06:21 AM 4/24/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
>
>All this talk about electric pump operating lights prompts me to get
>comments on an idea I had: Put a pressure switch in the line between the
>mechanical pump and the carburetor or injector servo. When the fuel
>pressure drops below the switch point a latching relay is energized, turning
>on the electric pump. Of course, as soon as the electric pump starts
>delivering pressure the switch will turn back off, but the latching relay
>will keep the pump on. The hold circuit to the latching relay can be
>interrupted with the fuel pump switch, which would be of the on-off-on
>variety, one of the on positions being the "automatic" setting and the other
>a positive on. On master-on, turn the switch to the auto position,
>verifying that the pump turns on and stays on, then turn it off to shut it
>off for engine starting (just to reduce battery draw during cranking). Then
>turn it back to the auto position for the flight. The relay would also turn
>on an "electric pump operating" light, as otherwise there would be no way to
>know if the mechanical pump failed during flight. I think the extra
>complexity is worth it as it removes the pilot from a critical failure mode
>scenario. To assume the pilot will always remember to turn on the electric
>pump in case a sudden silence is a false assumption. My partner experienced
>just such a silence and he never tried the electric pump - in this case it
>wouldn't have done any good anyway, but the point remains that to rely on
>human performance in an emergency is a weak design philosophy.
This idea has sound foundations. On the same topic, many manufacturer's
-AND- builders install indicator lights to annunciate functionality
when in fact, the illuminated lamp only shows that the lamp is good
and a switch is ON. For example, any lamp wired to simply echo a
switch position for control of any accessory only guarantees that the
switch is ON, the circuit breaker is IN and the light bulb is GOOD.
If it is important that such lamps offer MORE assurance, the methodology
of installation needs more consideration. For example, pitot heater systems
on many RAC aircraft circulate heater current though a current detector.
Here's the po' mans version
http://www.aeroelectric.com/Pictures/CurrentSense.jpg
Use the magnetic reed switch to turn ON a lamp that say's
PITOT HEAT. If that lamp is off, the power to the heater is
OFF -or- the circuit is OPEN in spite of the fact that
pitot heat control switch is ON.
The same kind of sensor can be used on nav, landing and taxi
lights. Here the reed switch is used to keep a LAMP FAIL light
off.
Such a sensor in series with a fuel pump would at least assure
that the pump was drawing some kind of current and that the
annunicator light wasn't simply announcing that 14v was being
applied to an open circuit.
Of course, in the case of pumps, it's better to test and
annunicate proper operation as far downstream of the functionality
chain as possible . . . like Gary's suggestion above to
annunciate and control things base on pressure sensing.
When you contemplate any kind of annunciation, do the
failure mode effects analysis to see what that light REALLY
means and what it's shortcomings are for telling you
what you'd really like to know.
Bob . . .
Message 6
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| Subject: | Re: current flow |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 09:14 AM 4/24/2004 -0400, you wrote:
>--> AeroElectric-List message posted by: "Gordon Robertson"
><grobertson@verizon.net>
>
> >>The negative terminal is called that because electrons are negatively
>charged,
>
> >>and it has the excess. The positive terminal lacks electrons, and seeks
>them.
>
>
>This is always confusing to the non-electrical engineer. It comes about
>because before folks recognized that current was a flow of electrons, and
>were experimenting with batteries, they just picked one battery terminal as
>*positive* and one as *negative*. Could easily have picked it the other
>way around. Unfortunately, when they realized that the electrons actually
>flowed the other way from what they had picked, the only solution was to
>define the electron charge as negative. Everything else follows from that
>single unfortunate guess.
Even electrical engineers have problems when they
study from old texts which are perfectly "correct"
in their presentations but adopt the conventions
of popular writings in 1920. Virtually all modern
texts use the (-) terminal of a source as emitter of
electrons as "current". I have many books in my
library where the sense is reversed. This was quite
common before vacuum tubes. Electron mobility
was known and understood long before vacuum tubes
and is mentioned in the books that speak of current
as a flow opposite that of the electrons!
It makes sense that the (-) terminal is the source
of electrons since they carry what was also deemed
a "negative" charge. One can adopt either convention for the
purposes of studying things under the umbrella of Kirchoff's laws.
You simply need to be consistent throughout the study. Calling
the emitter of both CURRENT and electrons the (-) terminal for
any source maintains the consistency for electron current
flow and induced voltages. Consider what happens in the
discussions presented in:
http://www.aeroelectric.com/articles/spikecatcher.pdf
In the figure on the first page, we see voltage across
an inductor (contactor coil) shown as +12 volts at the
top of the coil when the contactor is energized. During
this time, electrons are moving up from ground or - terminal
of battery to the top terminal that is connected to
the bus or + terminal of battery. We know that while
capacitors dynamically resist change of voltage, inductors
dynamically resist change of current. It follows then that
as the switch opens, the collapse of magnetic field tries
to SUSTAIN the flow of current. In this case, the normal
flow of electrons from the upper terminal of the coil
becomes a torrent of electrons in the same direction as
the switch opens. Hence the top of the coil becomes the
(-) terminal of a current source and we can measure a
negative going voltage of substantial amplitude at this
terminal with respect to ground.
It more than a matter of flipping the coin for
choosing which terminal of a battery is a current
source. We need to use the same convention for ALL sources
(and loads were the signs are reversed) so that
all pieces of the lego-set will mate together
without spinning the hon. Mr. Kirchoff in his
grave.
I've mentioned this before but it's always worth repeating.
My all time favorite publication on electron physics
is Electronic Fundamentals Circuits, Devices and
Applications by Thomas L. Floyd. New ones are $100
retail. Used ones are abundantly available for under
$10 with examples at:
http://www.amazon.com/gp/product/offer-listing/067521310X//103-6674777-4163850?condition=all
Don't worry about edition dates. They're ALL worth
the few dollars you'll pay for one. I keep two extra
copies on my shelves to give away to any visitors
(especially kids) who show an encouraging spark of
interest in this stuff.
There's also copy of a US Navy course in electronics
on the CD from my website which you can download
at:
http://www.aeroelectric.com/CD/AEC8_0.zip
Unfortunately, these documents have a lot of
boiler-plate and the explanations are not nearly
as clear as Mr. Floyd's book . . . but it IS
free.
Bob . . .
Message 7
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| Subject: | circuit breaker buss bar |
--> AeroElectric-List message posted by: "Jim Lane" <jlane@crosscountybank.com>
PB circuit breakers are labeled LINE ane LOAD. Which side of the breaker is the
buss bar to be attached, and will the breaker trip should an overload occur if
the buss bar and wires are reversed?
Message 8
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| Subject: | Re: circuit breaker buss bar |
--> AeroElectric-List message posted by: Charlie & Tupper England <cengland@netdoor.com>
Jim Lane wrote:
>--> AeroElectric-List message posted by: "Jim Lane" <jlane@crosscountybank.com>
>
>PB circuit breakers are labeled LINE ane LOAD. Which side of the breaker is the
buss bar to be attached, and will the breaker trip should an overload occur
if the buss bar and wires are reversed?
>
Buss bar goes to LINE. LOAD goes to the load (light, pump, etc.).
Unless the breaker obeys some FAA reg instead of the laws of physics, I
can't think of a good reason why reversing the terminals would prevent
the breaker tripping.
Charlie
Message 9
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| Subject: | Re: cell phone antenna |
--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
richard@riley.net wrote:
> --> AeroElectric-List message posted by: richard@riley.net
>
> At 12:20 PM 4/23/04 -0500, you wrote:
>
>>--> AeroElectric-List message posted by: jerb <ulflyer@verizon.net>
>>
>>It's is still illegal today as far as I know - you'll need an Air-Phone if
>>you want to have legal phone service while airborne or maybe one of them
>>Iridium satellite jobs.
>>jerb.
>
>
> Here's the memo I wrote for work, use at your own risk, I'm not a lawyer,
> your mileage may vary, etc.
The phones in common use today that most people call "cellular" phones are not
cellular (AMPS) phones by the definition of the FCC. They are PCS devices and
operate under different rules. As far as I am aware there is no prohibition
by the FCC from operating these devices in flight. If you are operating under
part 91 of the FARs and have determined that the device in question is not causing
interference with the flight and navigation equipment, I am not aware of
any reason the FAA would be unhappy either.
--
Brian Lloyd 6501 Red Hook Plaza
brianl@lloyd.com Suite 201
http://www.lloyd.com St. Thomas, VI 00802
+1.340.998.9447 (voice) +1.360.838.9669 (fax)
There is a time to laud one's country and a time to protest.
A good citizen is prepared to do either as the need arises.
Message 10
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| Subject: | Re: Fuel pressure warning light |
--> AeroElectric-List message posted by: klehman@albedo.net
One should be able to accomplish this with just a $2. comparator circuit
in cases like mine where I already have an electric fuel pressure gauge
and also a computer controlled relay to feed power to the pump. From
memory I believe the electric sender feeds up to 5 volts to the Grand
Rapids engine monitor.
A certain Subaru converter specifies a pressure switch and an extra (and
complicated) relay for this purpose on his 38 psi fuel system. Actually
in that particular case it controls the second electric efi fuel pump. I
believe there were some problems with the first pressure switch that was
specified though and it seemed like a complicated way to achieve the
goal compared to a bit of silicon.
Ken
Gary Casey wrote:
> --> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
>
> All this talk about electric pump operating lights prompts me to get
> comments on an idea I had: Put a pressure switch in the line between the
> mechanical pump and the carburetor or injector servo. When the fuel
> pressure drops below the switch point a latching relay is energized, turning
> on the electric pump. Of course, as soon as the electric pump starts
> delivering pressure the switch will turn back off, but the latching relay
> will keep the pump on. The hold circuit to the latching relay can be
> interrupted with the fuel pump switch, which would be of the on-off-on
> variety, one of the on positions being the "automatic" setting and the other
> a positive on. On master-on, turn the switch to the auto position,
> verifying that the pump turns on and stays on, then turn it off to shut it
> off for engine starting (just to reduce battery draw during cranking). Then
> turn it back to the auto position for the flight. The relay would also turn
> on an "electric pump operating" light, as otherwise there would be no way to
> know if the mechanical pump failed during flight. I think the extra
> complexity is worth it as it removes the pilot from a critical failure mode
> scenario. To assume the pilot will always remember to turn on the electric
> pump in case a sudden silence is a false assumption. My partner experienced
> just such a silence and he never tried the electric pump - in this case it
> wouldn't have done any good anyway, but the point remains that to rely on
> human performance in an emergency is a weak design philosophy.
>
> Gary Casey
Message 11
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| Subject: | Re: circuit breaker buss bar |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:53 PM 4/24/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: "Jim Lane"
><jlane@crosscountybank.com>
>
>PB circuit breakers are labeled LINE ane LOAD. Which side of the breaker
>is the buss bar to be attached, and will the breaker trip should an
>overload occur if the buss bar and wires are reversed?
I'll have to ask my cb guru at Eaton about this. I believe the
housings are marked so that special breakers with trip annunciators
or external trip inputs get wired properly. For the plain vanilla,
two terminal, thermal breaker, I cannot think of any reason for it
to make a difference. I've wired them both ways and they've worked
fine. I'll confirm my hypothesis with someone who is in the business.
Bob . . .
Message 12
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--> AeroElectric-List message posted by: "Emrath" <emrath@comcast.net>
Listers: Does anyone have a CAD drawing of a basic RV-6 panel. I have
TurboCAD 4 and would like to start planning out panel using this. Please
contact me directly if you can assist. Thanks. Marty in Brentwood, TN
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