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dlj04(at)josephson.com Guest
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Posted: Fri Jan 16, 2015 8:16 am Post subject: ASTM F2245 |
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Bob Nuckolls responded to my post
> For $75 a year you can join ASTM and get all of the standards that
> apply to aviation for free (you want ASTM volume 15 with your
> membership.) And, you're then welcome to join the deliberation on
> what they should include. End-users and other interested people are
Quote: | Excellent point . . . I'll do that. I'll also
write to suggest that non-for profit distribution
should be allowed . . .
You might consider instead writing a summary of the current standard
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without the legalese. It will be both more useful and less threatening to
the legal beagles.
Quote: |
Like RTCA, ASTM is at risk for becoming 'siloed' . . .
relatively isolated from accurate and useful
feedback from the very folks who would are supposed
to "benefit" by the best of what the specs have to offer
. . . and like the EAA feedback into AC43-13 many
years ago . . . a conduit for refinement.
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That's right. I should also point out that the 2007 version of the
standard that's on the recreationalflying download site is quite
different from the current one. And, this very issue of circuit
protective devices has just been worked on, and is the subject of a
ballot in F37.20 which closes on January 30. There is still some
argument about the language, so I expect at least one more round of
discussion before it's done, and the time is right now to propose
alternate wording. ASTM, like most standards bodies, requires "the
absence of sustained objection" to new standards language, or has to
show a thorough review about why an objection is technically not valid.
As proposed now, circuit overload protection must be installed on each
circuit containing wiring rated for less than the combined output of the
battery and alternator, must open before the conductor emits smoke, must
not automatically reset, and must be accessible to and in clear view of
the pilot if it covers required equipment, equipment essential to safety
of flight unless redundant equipment is provided, or switchable circuit
protection installed to accommodate aircraft operating procedures
(combined switch/breaker). So a fusible link (not accessible in flight)
to protect wiring to the starter would be OK unless the manufacturer
decided that in-flight starter operation was essential.
David Josephson
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jluckey(at)pacbell.net Guest
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Posted: Fri Jan 16, 2015 10:45 am Post subject: ASTM F2245 |
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Boy this is all very interesting and wierd coincidence on the timing.
I have a few thoughts:
1. I am a firm believer in protecting feeders. I would rather blow a fuse/current limiter
that I can't reset in flight, than catch on fire. Absolutely no question about it.
If I had an electrically dependent engine, and was dumb enough not to have redundant
power, I would rather be flying a glider than a glider that is on fire. This idea seems
obvious to me. And the recent posting re the RV-12 fire reinforces this idea.
2. After reviewing F2245 it seems strange that not only is such circuit protection not
recommended but it is specifically prohibited. Seems like adding insult to injury. It must
be due to the fact that small GA does not protect this feeder - but I don't believe that protection
of this wire is specifically prohibited by the FARs.
3. Now, as BobN has informed us, the GA manufacturers decided a long time ago that
protection was not necessary for this feeder. I sure would like to talk to someone who
was in the room when that decision was made. I would like to know the thought
process & what criteria was being considered. And if BobN does not know who
these people were/are, then I don't know who would. I'm guessing that they came to a
logical conclusion based on the criteria and context of the moment. But without know
some of that context, it is difficult to understand.
4. In all other disciplines of electrical engineering (and I've worked on
everything from Motor Homes to Mega-yachts, commercial & residential electrical
contracting, etc.) there are codes, regulations, guidelines, or just plain old best practices
that prohibit un-protected feeders. Why did the aviation community decide not to
protect this particular wire?
Just trying to get a little smarter...
-Jeff
On Friday, January 16, 2015 8:27 AM, David Josephson <dlj04(at)josephson.com> wrote:
--> AeroElectric-List message posted by: David Josephson <dlj04(at)josephson.com (dlj04(at)josephson.com)>
Bob Nuckolls responded to my post
> For $75 a year you can join ASTM and get all of the standards that
> apply to aviation for free (you want ASTM volume 15 with your
> membership.) And, you're then welcome to join the deliberation on
> what they should include. End-users and other interested people are
Quote: | Excellent point . . . I'll do that. I'll also
write to suggest that non-for profit distribution
should be allowed . . .
You might consider instead writing a summary of the current standard
|
without the legalese. It will be both more useful and less threatening to
the legal beagles.
Quote: |
Like RTCA, ASTM is at risk for becoming 'siloed' . . .
relatively isolated from accurate and useful
feedback from the very folks who would are supposed
to "benefit" by the best of what the specs have to offer
. . . and like the EAA feedback into AC43-13 many
years ago . . . a conduit for refinement.
|
That's right. I should also point out that the 2007 version of the
standard that's on the recreationalflying download site is quite
different from the current one. And, this very issue of circuit
protective devices has just been worked on, and is the subject of a
ballot in F37.20 which closes on January 30. There is still some
argument about the language, so I expect at least one more round of
discussion before it's done, and the time is right now to propose
alternate wording. ASTM, like most standards bodies, requires "the
absence of sustained objection" to new standards language, or has to
show a thorough review about why an objection is technically not valid.
As proposed now, circuit overload protection must be installed on each
circuit containing [quote][b]
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dlj04(at)josephson.com Guest
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Posted: Sat Jan 17, 2015 10:38 am Post subject: ASTM F2245 |
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On 1/16/15 11:59 PM, Jeff Luckey wrote:
Quote: | 2. After reviewing F2245 it seems strange that not only is such
circuit protection not recommended but it is specifically prohibited.
Seems like
With all due respect, that is simply false with respect both to the
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subcommittee's intent (having been a participant or observer in many of
the discussions on this topic) and the current language. People are
commenting on an obsolete edition of the standard that someone pirated
on to the net, not even the current one, and certainly not the one that
is being further refined this month.
Second, a standard permits or prohibits nothing. The point of a standard
is to set a definition which can be referred to. It has no regulatory
impact. FAA will accept a manufacturer's assertion of compliance with
this particular standard as indicating compliance with the light-sport
rules, and will consider others if proposed to them.
If you don't like the standard as it is, get involved in changing it.
The process is very unlike the FAA's rulemaking process: rather than
staying the same for decades, the default is review and updating to meet
current best practices. I have been part of that effort for two years.
It takes some time, and I believe it's worthwhile. I'm involved in
several other standards-making bodies and the ASTM process is faster and
more accessible than most. But it is dependent on the good-faith efforts
of everyone interested in the outcome.
David Josephson
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nuckolls.bob(at)aeroelect Guest
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Posted: Sat Jan 17, 2015 11:21 am Post subject: ASTM F2245 |
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Quote: | It takes some time, and I believe it's worthwhile. I'm involved in
several other standards-making bodies and the ASTM process is faster
and more accessible than most. But it is dependent on the good-faith
efforts of everyone interested in the outcome.
David Josephson
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Well put . . .
Bob . . .
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jluckey(at)pacbell.net Guest
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Posted: Sat Jan 17, 2015 11:30 am Post subject: ASTM F2245 |
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"With all due respect, that is simply false with respect both to the subcommittee's intent (having been a participant or observer in many of the discussions on this topic) and the current language. "
OK, very good, I'm pleased to hear that. I must be looking at an old copy as you mention and/or factoring in other people's interpretation - bad on me. However, there is evidence that people are interpreting the standard as though it prohibits protecting the feeder in question, however incorrect that may be.
"Second, a standard permits or prohibits nothing. The point of a standard is to set a definition which can be referred to."
I agree in theory, however in practical application people interpret (or mis-interpret) standards like this as though they do permit or prohibit.
Thanks for the clarification,
-Jeff
On Saturday, January 17, 2015 10:52 AM, D L Josephson <dlj04(at)josephson.com> wrote:
--> AeroElectric-List message posted by: D L Josephson <dlj04(at)josephson.com (dlj04(at)josephson.com)>On 1/16/15 11:59 PM, Jeff Luckey wrote:> 2. After reviewing F2245 it seems strange that not only is such > circuit protection not recommended but it is specifically prohibited. > Seems likeWith all due respect, that is simply false with respect both to the subcommittee's intent (having been a participant or observer in many of the discussions on this topic) and the current language. People are commenting on an obsolete edition of the standard that someone pirated on to the net, not even the current one, and certainly not the one that is being further refined this month.Second, a standard permits or prohibits nothing. The point of a standard is to set a definition which can be referred to. It has no regulatory impact. FAA will accept a manufacturer's assertion of compliance with this particular standard as indicating compliance with the light-sport rules, and will consider others if proposed to them.If you don't like the standard as it is, get involved in changing it. The process is very unlike the FAA's rulemaking process: rather than staying the same for decades, the default is review and updating to meet current best practices. I have been part of that effort for two years. It takes some time, and I believe it's worthwhile. I'm involved in several other standards-making bodies and the ASTM process is faster and more accessible than most. But it is dependent on the good-faith efforts [quote][b]
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