Today's Message Index:
----------------------
1. 06:14 AM - Re: Re: GRT EIS-Fuel Sender (Robert L. Nuckolls, III)
2. 06:26 AM - Re: Re: GRT EIS-Fuel Sender (Robert L. Nuckolls, III)
3. 08:16 AM - Re: GPS outage in fiberglass plane (checkn6)
4. 09:48 AM - Noise in the intercom . . . (Robert L. Nuckolls, III)
5. 09:48 AM - Re: GRT EIS-Fuel Sender (jonlaury)
6. 12:56 PM - Re: splicing wire? (Robert L. Nuckolls, III)
7. 01:46 PM - Re: Re: splicing wire? (James Robinson)
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: GRT EIS-Fuel Sender |
At 09:07 PM 8/27/2010, you wrote:
>
>Bob, you said:
>
> > That "unusable fuel" has two important functions.
> > (1) provide a low-spot for moisture collection
> > and (2) keep the vapor in the tank saturated.
>
>
>I spent a lot of time and effort to make sure that every drop in my
>fuel tanks was usable except for the debris sumps. The mains and
>header can be pumped dry except for sump fuel (4-6 ounces).
>
>Is the small amount of fuel in the sumps enough to keep a 12' long
>wing tank vapor-saturated?
Are these 'sumps' part of the tank envelope
or are they 'low spot' water separators plumbed
to the tank through a fuel line?
>I wasn't ever worried about this before, but now that it's out on
>the line, just want to be sure I'm not committing a major oversight.
I may have stubbed my toe on speaking of the
"importance" of unusable fuel. I don't think
that the designers deliberately shoot for a
volume of unusable fuel just to meet some rule
of thumb for reducing risk of explosion. I
think it has just worked out that for most airplane
tanks, the lowest spot in the tank was against the
skin and that same spot becomes a good place to
put a water drain. Obviously, plumbing a fuel
line into the same location would look pretty ugly
hanging out the bottom of the airplane. So fuel
lines tend to tap through the tank wall at the lowest
practical point . . . but obviously above the
tank's low spot thus giving rise to "unusable
fuel".
I'm sure there are many instances of gasoline
tanks on vehicles that are plumbed such that
the total contents can be consumed by the engine.
But unless the same tank is force-ventilated
the vapor space mixture will remain very rich
for long periods of time. But even after it
becomes 'leaner', you still need an ignition
source for the combination to become hazardous.
I remember reading about WWII military fuel
systems where a major consideration was taking
a tracer through an empty fuel tank. At Cessna,
we fitted some military airplane tanks with an
open cell foam filler. While the foam reduced
tank useful volume by about 5%, it had the
effect of sucking the heat out of a flame front
such that taking a tracer through a tank of
stoichiometric mixture would not produce an
explosion.
It's hard to get an explosion to happen on
purpose. I recall some conversations with a
fellow who ran a test lab telling us about
getting a mixture tuned up "just right" for
the purposes of testing our motors for explosion
proofing. He described a chamber with a hinged
lid, foam gaskets all around the edges, and just enough
weight to get a good seal.
The chamber was fitted with mixing fans, a
source of hydrocarbon (I think it was Butane),
a source of ignition (spark plug through the
wall), and equipment to allow us to run a motor
inside.
After putting what is believed to be the
right amount of butane in the chamber, the
motor run tests are conducted. When the
prescribed tests are finished, he then sparks
the mixture for the purpose of proving that
the atmosphere was and is still hazardous.
If things went right, the vapor lit off,
the lid flies open and you get this fireball
out the top. If things don't go right, nothing
happens and the tests have to be repeated.
Unless you plan to punch holes in your tanks
and mount spark plugs in the holes, the practice
of running the tanks dry offers no great hazard.
If you're using fuel gaging systems that are shown
to be intrinsically safe in a hazardous environment,
you're good to go.
Bob . . .
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: | Re: GRT EIS-Fuel Sender |
At 09:21 PM 8/27/2010, you wrote:
>
>You don't have to run the tanks dry.
True . . . but if one intends to leave a specific
volume of fuel in the tank, an accurate means
of gaging is indicated.
I just checked out my copy of part 23 where I found:
------------------------------
Sec. 23.971 Fuel tank sump.
(a) Each fuel tank must have a drainable sump with an effective capacity,
in the normal ground and flight attitudes, of 0.25 percent of the tank
capacity, or 1/16 gallon, whichever is greater.
(b) Each fuel tank must allow drainage of any hazardous quantity of water
from any part of the tank to its sump with the airplane in the normal ground
attitude.
(c) Each reciprocating engine fuel system must have a sediment bowl or
chamber that is accessible for drainage; has a capacity of 1 ounce for every
20 gallons of fuel tank capacity; and each fuel tank outlet is located so
that, in the normal flight attitude, water will drain from all parts of the
tank except the sump to the sediment bowl or chamber.
(d) Each sump, sediment bowl, and sediment chamber drain required by
paragraphs (a), (b), and (c) of this section must comply with the drain
provisions of Sec. 23.999 (b)(1) and (b)(2).
-------------------------------
So in TC airplanes, it would be a violation to design
a tank with zero unusable fuel. This section gives us
some insight into the existence of one or more
drains in each tank plus a low spot drain (usually
the gascolator) at the bottom of the fire wall.
Bob . . .
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: GPS outage in fiberglass plane |
I agree, but I am going to go one small step further and do the frequency test
while on the ground the next time I go to the airport. I too have had GPS drop-out
for brief periods and just thought that I had gotten a bum deal on EBAY on
my little hand held Garmin 196. I still have a plan A and plan B since my little
GPS is more for informational purposes only and is really a plan C.
Thanks for starting this thread.
My wife thinks I'm nuts for reading this "boring stuff" but I love learning new
things and once again I found a little gem to check on.
Chris
[quote="james(at)etravel.org"]Interesting stuff. That's worth everyone with a
GPS tucking away in
the "for future reference" part of the brain. Thanks for taking the
time to report this info.
James
While on the tiedown, with engine and everything running, I started to tune in
the various com frequencies I use in my area. With the GPS screen set to show
the sat reception bars, I quickly found that the bars would quickly pulse down
to nothing when the frequency was set between 119.200 to 119.5. This was even
without transmitting and it was dramatic. As it turns out, I am usually tuned
within this frequency range when flying the routes I had associated with GPS
loss.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=310382#310382
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: | Noise in the intercom . . . |
>Comments/Questions: I have alternator noise in my Sigtronics
>intercom. I re-wired and re-routed the harness out of the tunnel
>(Glasair III) to around the cockpit - no help.
>
>I get alternator noise with the intercom on, quiet with it off, and
>/or the ALT CB pulled. I also get aditional noise when the fuel
>pump or flap motor are run (but not always). I'm kinda stumped.
>
>I've [now] been told that pulling the CB can hurt the alternator...true?
No
>Also that a bad diode in the alternator can cause this noise?
Sometimes . . . but if you have other accessories
that cause noise too . . . then the problem is
most likely more general and involves how the
intercom was installed.
>I had the alternator rebuilt to no effect, so I thought that had
>eliminated the alternator, but I could be wrong. I also have
>replaced the (B&C) voltage regulator.
>
>Suggestions and/or help would be appreciated.
I'm sorry to hear that you've tried so many
hopeful and expensive fixes without positive
result. I note that you are not currently
subscribed to the AeroElectric-List.
Early on (after reading your symptoms)
I and others on the list would have steered
you toward an evaluation of your ground
system. The problems you've described are
almost certainly a function of shared
pathways in the ground system for both
victim (intercom) and antagonists (alternator,
flaps, etc).
These issues are also addressed in the
chapters on Grounding and Noise found
in the AeroElectric Connection.
If you do not have a copy of the Connection
you can download it here:
http://www.aeroelectric.com/Book/AEC12A_PDF.zip
I'll suggest also that you join us on the
List for expanded support of your quest for
solving this problem. Never met a noise dragon
that couldn't be slain.
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: GRT EIS-Fuel Sender |
>
> You don't have to run the tanks dry.
>
True and I probably won't 99% of the time. But I designed this multi-tank fuel
system to be bullet proof if it is just ON. I don't want to inadvertently build
in a gotcha if there's a need or a screw-up that runs a tank dry.
Re Bob's Part 23 quote, by coincidence, my wing and header tanks (with integral,
drainable debris sumps within the tank envelope) are configured in conformance,
as they drain into a 32 oz. sump tank (w/drain) that feeds the pumps.
So now all I have to do is remove the fuel tank spark plugs. :D
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=310391#310391
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: splicing wire? |
At 01:57 PM 8/28/2010, you wrote:
>Good afternoon Bob
>I have a question on splicing wire. I need to lengthen the wires to
>my headset plugs from the intercom. ( NAT intercom). They currently
>go to plugs in the center console. I was originally going to run
>new wires all the way to the intercom. This is proving to be a
>major undertaking. Everything is bundled and nicely tied and very
>difficult to get to. Can I add a length of wire to the existing
>without creating problems? Would there be any considerations I
>would need to address?
Sure. the big guys do it all the time. They use a
product called solder-sleeves. You don't need to get
THAT fancy. I've illustrated a poor-man's solder sleeve
technique here:
http://aeroelectric.com/Pictures/Wiring_Technique/Wire_treatment_3.jpg
and a comic book on the technique here:
http://aeroelectric.com/articles/Solder_Lap_Splicing/Solder_Lap_Splices.html
If you have some shields to deal with, just bring
their pigtails together as if they were individual
wires.
This technique offers a minimum-bulk methodology
for jointing wires and insulating the splice. If practical,
you might want to trim the lengths of the existing
wires so that the splices don't all bunch up next
to each other in the finished bundle.
Bob . . .
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: splicing wire? |
Thank you Bob!!
James Robinson
Glasair lll N79R
Spanish Fork UT U77
________________________________
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Sat, August 28, 2010 1:26:30 PM
Subject: AeroElectric-List: Re: splicing wire?
At 01:57 PM 8/28/2010, you wrote:
Good afternoon Bob
>I have a question on splicing wire. I need to lengthen the wires to my headset
>plugs from the intercom. ( NAT intercom). They currently go to plugs in the
>center console. I was originally going to run new wires all the way to the
>intercom. This is proving to be a major undertaking. Everything is bundled and
>nicely tied and very difficult to get to. Can I add a length of wire to the
>existing without creating problems? Would there be any considerations I would
>need to address?
Sure. the big guys do it all the time. They use a
product called solder-sleeves. You don't need to get
THAT fancy. I've illustrated a poor-man's solder sleeve
technique here:
http://aeroelectric.com/Pictures/Wiring_Technique/Wire_treatment_3.jpg
and a comic book on the technique here:
http://aeroelectric.com/articles/Solder_Lap_Splicing/Solder_Lap_Splices.html
If you have some shields to deal with, just bring
their pigtails together as if they were individual
wires.
This technique offers a minimum-bulk methodology
for jointing wires and insulating the splice. If practical,
you might want to trim the lengths of the existing
wires so that the splices don't all bunch up next
to each other in the finished bundle.
Bob . . .
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! --
|