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nuckolls.bob(at)aeroelect
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 Posted: Mon Jul 29, 2013 7:43 pm Post subject: FAR 23 and airplanes of any stripe |
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Excellent point. But with that configuration, it doesn't make sense to put the starter contactor on the firewall because I'll still need to run the alternator wire all the way up to the front anyway. I was planning on an ANL50 for protection.
Why? Did I miss something in the deliberations?
I'd put the starter contactor as close to where the other loads are as possible. If you have the battery in the back for W&B considerations you're going to have to run a heavy gauge cable to the starter in the front. Put the contactor on the firewall then everything gets to take advantage of this big heavy wire when you're not cranking.
Okay, refresh my memory. I thought we were talking
about a canard pusher with battery in nose.
I realize that you aren't required to build to Part 23 standards but some of them do make sense. Part 23 requires that circuit protection devices for loads critical to safety of flight be resettable or replaceable by the flight crew while in flight. What stuff are you powering with the alternator you'd like to have if you're flying VFR on top at night over Nevada somewhere? How would you fly and replace an NL50 fuse? Where would you put it so it would be handy? Carrying a spare NL50? That's required too (in Part 23).
Actually it is not. The relevant paragraph is here:
Sec. 23.1357 Circuit protective devices.
(a) Protective devices, such as fuses or circuit breakers, must be installed in all electrical circuits other than--
(1) Main circuits of starter motors used during starting only; and (2) Circuits in which no hazard is presented by their omission.
(b) A protective device for a circuit essential to flight safety may not be used to protect any other circuit.
(c) Each resettable circuit protective device ("trip free" device in which the tripping mechanism cannot be overridden by the operating control) must be designed so that--
(1) A manual operation is required to restore service after tripping; and (2) If an overload or circuit fault exists, the device will open the circuit regardless of the position of the operating control.
(d) If the ability to reset a circuit breaker or replace a fuse is essential to safety in flight, that circuit breaker or fuse must be so located and identified that it can be readily reset or replaced in flight.
(e) For fuses identified as replaceable in flight--
(1) There must be one spare of each rating or 50 percent spare fuses of each rating, whichever is greater; and (2) The spare fuse(s) must be readily accessible to any required pilot.
1357.d speaks to 'essential to safety in flight' . . . okay suppose
you have a breaker that protects the only radio on the panel and you're
anticipating a launch into the murk. How many things in that radio can
'break' and render the radio inop? Don't know but you can bet it's a bunch.
What is the likelihood that ANY kind of radio killing event will cause
the breaker to operate yet be 'clear' in some manner that allows the breaker
to be reset?
Once a circuit protective device operates, the very high probability
assumption is that the powered device is no longer available
irrespective of root cause for the trip. At the same time, a
tripped breaker suggests that the device did it's job to prevent
electrically induced fire or wire damage. Once the breaker or fuse
has operated, do you really want to give it a second chance of
doing more damage?
Pilots in the big iron birds are told to leave popped breakers
alone . . . but if you're feeling lucky . . . reset one time only.
Failure tolerant design goals say that probability for comfortable
termination of flight is greatly enhanced if EVERY device
has a no-sweat backup. This includes the alternator. This
is the operating philosophy that birthed the e-bus about 20 years
ago. It's the philosophy that birthed Z-13/8 shortly thereafter.
That same philosophy is satisfied by having battery powered hand-helds
in the flight bag.
http://tinyurl.com/d5mrjgh
In other words, with careful management of known energy
requirements, it's no big deal to have greater electrical
endurance than fuel endurance. Hence, all things electric are
relieved of their sweat-breaking criticality and there's no
good reason to fiddle with any circuit progective device
in flight.
Yes, you're right. It's probably safer to design the alternator circuit for continuous duty. If you design to Part 23 your loads should never exceed 80% of generating capacity. This was really hard to do before there were LED and HID landing lights. Old tube radios really wolfed down the juice too.
The 80% rule was never intended to de-rate an
engine driven power source. It was intended to
wall off head-room for battery recharge in
some nominal period of time after takeoff . . .
no hard numbers here but 60-90 minutes has been
the rule of thumb . . . and is obviously driven
by the sized of the battery.
In fact, it's the dead-battery recharge scenario
that drove a number tense events for pilots. I've
often referred to the type-certificated, 60A B-lead
breaker on tens of thousands of airplanes fitted with
60A alternators as, "the breaker designed to nuisance trip."
A cold alternator recharging a dead battery will
put out significantly more than its nameplate rating.
I jump started a Cherokee 140 out of 1K1 and about
15 minutes out, the panel went black. B-lead breaker
was popped but resetting it did not bring the alternator
back. I'm guessing that the alternator load-dump
zorked something.
In any case, I finished the leg on hand-helds,
put a charger on the battery in Sallisaw and
flew home battery-only with minimal loads backed
up by hand-held. A no-sweat trip.
Your b-lead protection would do well to emulate
Beech and many others by switching to current
limiters (VERY robust fuses) on the firewall.
These DO NOT nuisance trip but will perform
intended functions for shorted diodes.
In spite of this level of robustness, there are
still many things that can take the alternator down
that a pilot is ill-advised to mess with while
in flight. Plans-B, C and even D outweigh a box
full of tools any day.
See Chapters 10 and 17 in the 'Connection. Also
articles at:
http://tinyurl.com/mpdjsef
http://tinyurl.com/mthp9u4
http://tinyurl.com/nxgdccs
http://tinyurl.com/7lhbbah
This table (Figure 11-2) really sets the allowable voltage drop over the length of the wire. In a circuit where wire size is dominated by current carrying capacity like the relatively short alternator wire, this table doesn't dictate wire size. If the alternator is mounted on the front of the engine, it could be 8-12 wire feet to get to the circuit protection device and another 4-6 wire feet to get back to the battery side of the starter contactor. Worst case that's between 12' and 20' and of wire (always use the next line up on the chart) and that says an 8 AWG wire. Then is it an 8 AWG or a 6 AWG? Depends on the thermal rating of the wire.
Circuit protection is classically installed as
close to the source of hazardous energy as practical. In
the case of the canard pusher with front mounted
battery, the current limiter would be mounted as
close to the starter contactor as practical and
the starter feeder used to take alternator energy
forward to the battery and bus structure.
Every "must" and "shall" in FAR23.1357 is easily
put to bed by well considered, failure tolerant
design. The most powerful failure tolerant design
goal says, "No single item in the electrical system
is necessary for me to comfortably terminate flight
at airport of intended destination without breaking
a sweat (or punching a circuit breaker back in)."
Too many stories like this have graced the pages
of the flying-rags . . .
http://tinyurl.com/kqo7jx8
. . .and for the most part, serve to illustrate how
little most pilots know about how their airplane's
systems really work. The sad thing is that the vast
majority of these stories should have played out
much differently . . . were in fact so ho-hum that
it wasn't worth writing for the magazine.
This my friends is what the 'Connection and these
forums are all about . . . A quest for ho-hum flying
where the most exciting features of a flight are
fantastic scenes viewed out the window.
Bob . . . [quote][b]
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billp(at)wwpc.com
Guest
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| Posted: Mon Jul 29, 2013 10:43 pm Post subject: FAR 23 and airplanes of any stripe |
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|
Damn Bob, you're so right! Why didn't I suggest that. Just charge the battery at every stop and do away with the alternator all together. 
By the way, a 15 minute overload in the Cherokee probably falls outside the definition of a "Nuisance Trip". And if you'd opened the breaker on the input to the regulator you probably would have been able to reset the Over Voltage Protection circuit in the regulator and get the alternator back on line. Just a guess that when the output breaker opened the output voltage spiked and the OVP latched. Have to remove all the power to it to get it to reset. But you probably knew that.
You're right I did miss the pusher configuration part. You da man!
Bill
Sent from my iPad
On Jul 29, 2013, at 8:42 PM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
[quote] Excellent point. But with that configuration, it doesn't make sense to put the starter contactor on the firewall because I'll still need to run the alternator wire all the way up to the front anyway. I was planning on an ANL50 for protection.
Why? Did I miss something in the deliberations?
I'd put the starter contactor as close to where the other loads are as possible. If you have the battery in the back for W&B considerations you're going to have to run a heavy gauge cable to the starter in the front. Put the contactor on the firewall then everything gets to take advantage of this big heavy wire when you're not cranking.
Okay, refresh my memory. I thought we were talking
about a canard pusher with battery in nose.
I realize that you aren't required to build to Part 23 standards but some of them do make sense. Part 23 requires that circuit protection devices for loads critical to safety of flight be resettable or replaceable by the flight crew while in flight. What stuff are you powering with the alternator you'd like to have if you're flying VFR on top at night over Nevada somewhere? How would you fly and replace an NL50 fuse? Where would you put it so it would be handy? Carrying a spare NL50? That's required too (in Part 23).
Actually it is not. The relevant paragraph is here:
Sec. 23.1357 Circuit protective devices.
(a) Protective devices, such as fuses or circuit breakers, must be installed in all electrical circuits other than--
(1) Main circuits of starter motors used during starting only; and (2) Circuits in which no hazard is presented by their omission.
(b) A protective device for a circuit essential to flight safety may not be used to protect any other circuit.
(c) Each resettable circuit protective device ("trip free" device in which the tripping mechanism cannot be overridden by the operating control) must be designed so that--
(1) A manual operation is required to restore service after tripping; and (2) If an overload or circuit fault exists, the device will open the circuit regardless of the position of the operating control.
(d) If the ability to reset a circuit breaker or replace a fuse is essential to safety in flight, that circuit breaker or fuse must be so located and identified that it can be readily reset or replaced in flight.
(e) For fuses identified as replaceable in flight--
(1) There must be one spare of each rating or 50 percent spare fuses of each rating, whichever is greater; and (2) The spare fuse(s) must be readily accessible to any required pilot.
1357.d speaks to 'essential to safety in flight' . . . okay suppose
you have a breaker that protects the only radio on the panel and you're
anticipating a launch into the murk. How many things in that radio can
'break' and render the radio inop? Don't know but you can bet it's a bunch.
What is the likelihood that ANY kind of radio killing event will cause
the breaker to operate yet be 'clear' in some manner that allows the breaker
to be reset?
Once a circuit protective device operates, the very high probability
assumption is that the powered device is no longer available
irrespective of root cause for the trip. At the same time, a
tripped breaker suggests that the device did it's job to prevent
electrically induced fire or wire damage. Once the breaker or fuse
has operated, do you really want to give it a second chance of
doing more damage?
Pilots in the big iron birds are told to leave popped breakers
alone . . . but if you're feeling lucky . . . reset one time only.
Failure tolerant design goals say that probability for comfortable
termination of flight is greatly enhanced if EVERY device
has a no-sweat backup. This includes the alternator. This
is the operating philosophy that birthed the e-bus about 20 years
ago. It's the philosophy that birthed Z-13/8 shortly thereafter.
That same philosophy is satisfied by having battery powered hand-helds
in the flight bag.
http://tinyurl.com/d5mrjgh
In other words, with careful management of known energy
requirements, it's no big deal to have greater electrical
endurance than fuel endurance. Hence, all things electric are
relieved of their sweat-breaking criticality and there's no
good reason to fiddle with any circuit progective device
in flight.
Yes, you're right. It's probably safer to design the alternator circuit for continuous duty. If you design to Part 23 your loads should never exceed 80% of generating capacity. This was really hard to do before there were LED and HID landing lights. Old tube radios really wolfed down the juice too.
The 80% rule was never intended to de-rate an
engine driven power source. It was intended to
wall off head-room for battery recharge in
some nominal period of time after takeoff . . .
no hard numbers here but 60-90 minutes has been
the rule of thumb . . . and is obviously driven
by the sized of the battery.
In fact, it's the dead-battery recharge scenario
that drove a number tense events for pilots. I've
often referred to the type-certificated, 60A B-lead
breaker on tens of thousands of airplanes fitted with
60A alternators as, "the breaker designed to nuisance trip."
A cold alternator recharging a dead battery will
put out significantly more than its nameplate rating.
I jump started a Cherokee 140 out of 1K1 and about
15 minutes out, the panel went black. B-lead breaker
was popped but resetting it did not bring the alternator
back. I'm guessing that the alternator load-dump
zorked something.
In any case, I finished the leg on hand-helds,
put a charger on the battery in Sallisaw and
flew home battery-only with minimal loads backed
up by hand-held. A no-sweat trip.
Your b-lead protection would do well to emulate
Beech and many others by switching to current
limiters (VERY robust fuses) on the firewall.
These DO NOT nuisance trip but will perform
intended functions for shorted diodes.
In spite of this level of robustness, there are
still many things that can take the alternator down
that a pilot is ill-advised to mess with while
in flight. Plans-B, C and even D outweigh a box
full of tools any day.
See Chapters 10 and 17 in the 'Connection. Also
articles at:
http://tinyurl.com/mpdjsef
http://tinyurl.com/mthp9u4
http://tinyurl.com/nxgdccs
http://tinyurl.com/7lhbbah
This table (Figure 11-2) really sets the allowable voltage drop over the length of the wire. In a circuit where wire size is dominated by current carrying capacity like the relatively short alternator wire, this table doesn't dictate wire size. If the alternator is mounted on the front of the engine, it could be 8-12 wire feet to get to the circuit protection device and another 4-6 wire feet to get back to the battery side of the starter contactor. Worst case that's between 12' and 20' and of wire (always use the next line up on the chart) and that says an 8 AWG wire. Then is it an 8 AWG or a 6 AWG? Depends on the thermal rating of the wire.
Circuit protection is classically installed as
close to the source of hazardous energy as practical. In
the case of the canard pusher with front mounted
battery, the current limiter would be mounted as
close to the starter contactor as practical and
the starter feeder used to take alternator energy
forward to the battery and bus structure.
Every "must" and "shall" in FAR23.1357 is easily
put to bed by well considered, failure tolerant
design. The most powerful failure tolerant design
goal says, "No single item in the electrical system
is necessary for me to comfortably terminate flight
at airport of intended destination without breaking
a sweat (or punching a circuit breaker back in)."
Too many stories like this have graced the pages
of the flying-rags . . .
http://tinyurl.com/kqo7jx8
. . .and for the most part, serve to illustrate how
little most pilots know about how their airplane's
systems really work. The sad thing is that the vast
majority of these stories should have played out
much differently . . . were in fact so ho-hum that
it wasn't worth writing for the magazine.
This my friends is what the 'Connection and these
forums are all about . . . A quest for ho-hum flying
where the most exciting features of a flight are
fantastic scenes viewed out the window.
Bob . . . | Quote: |
===================================
st">http://www.matronics.com/Navigator?AeroElectric-List
===================================
cs.com
===================================
matronics.com/contribution
===================================
|
[b]
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Tue Jul 30, 2013 11:13 am Post subject: FAR 23 and airplanes of any stripe |
|
|
At 01:42 AM 7/30/2013, you wrote:
| Quote: | Damn Bob, you're so right! Why didn't I suggest that. Just charge the battery at every stop and do away with the alternator all together.
By the way, a 15 minute overload in the Cherokee probably falls outside the definition of a "Nuisance Trip". |
I defined nuisance trip as a behavior in response to
an expected, normal condition.
| Quote: | | And if you'd opened the breaker on the input to the regulator you probably would have been able to reset the Over Voltage Protection circuit in the regulator and get the alternator back on line. Just a guess that when the output breaker opened the output voltage spiked and the OVP latched. Have to remove all the power to it to get it to reset. But you probably knew that. |
Tried that. This event 'killed' something. It was before
I owned the airport so I wasn't 'plugged in' to failure
analysis and repairs needed to restore the system.
Too many of our brothers in the heavier iron business
believed that 60A nameplate rating for an alternator
was a limit. Regulators for the generators replaced
by alternators featured a calibrated current limit control
relay. In this case, generator output and nameplate rating
were in lockstep.
[img]cid:.0[/img]
An alternator is inherently current limited but at a
value dependent on temperature. The nameplate rating is
worst case for max allowable operating temperature. In
OTHER conditions, the user should expect MORE than nameplate
output.
Failure to understand this feature prompted the folks to
keep the same breaker-to-nameplate rating as for the legacy
generators thus setting the stage for the relatively rare
but significant breaker tripping in response to a predictable
and expected operating condition. This drove my recommendations
for following in Beech's footsteps and using uber-robust
current limiters for b-lead protection.
[img]cid:.1[/img]
Note that a 35A ANL limiter will carry 80A at room
temperature for ever . . . but hit it with a shorted
diode fed by a battery and it opens in 100 mS or less.
This style of protection will not nuisance trip.
Bob . . .
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jloram
Joined: 07 Nov 2009
Posts: 54
Location: United States
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| Posted: Wed Jul 31, 2013 12:45 pm Post subject: FAR 23 and airplanes of any stripe |
|
|
Where would I find the FAA definition of "circuit essential to flight
safety"?
Thanks, -john-
(get'n close to inspection)
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Monday, July 29, 2013 8:43 PM
To: aeroelectric-list(at)matronics.com
Subject: FAR 23 and airplanes of any stripe
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Wed Jul 31, 2013 1:25 pm Post subject: FAR 23 and airplanes of any stripe |
|
|
At 03:45 PM 7/31/2013, you wrote:
| Quote: | Where would I find the FAA definition of "circuit essential to flight safety"?
|
There is no such definition that I know of. It's one
of those catch-all phrases that will be addressed
by the certification test plan for each airplane.
I wrote the cert test plan for the GP-180's electrical
system. We took each paragraph of the applicable FARS
and spoke to how requirements of that paragraph were
to be addressed. It's been almost 30 years but as I
recall, there were no circuits (or associated protective
devices) that were essential to flight safety. In
other words, any single circuit who's failure would
put the airframe at risk had (1) immediate notification
to crew that a failure had occurred and (2) a back-up
plan for that condition.
The idea that being able to reset a breaker for some
circuit that put the airplane at risk simply wasn't
a consideration. If a breaker trips, that system
is off line for the duration of the flight and
prudent design called for making such circuits
un-essential for comfortable termination of the
flight.
Failure tolerant design drives risks to insignificant
probability without having to prove 10-to-the-
minus-9 failure rates . . . the probability of
dual failures for 10-to-the-minus-4, 5 or 6
rates within an operating window of a single
tank of fuel is exceedingly small. Hence the
statement for identifying "circuits essential to
flight safety" have been moot for decades. Well
crafted machines have no such circuits.
Bob . . .
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kyrilian_av(at)yahoo.com
Guest
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| Posted: Fri Aug 02, 2013 5:07 pm Post subject: FAR 23 and airplanes of any stripe |
|
|
John,
The FAA publishes a range of Advisory Circulars that provide certification compliance guidance. These documents aren't technically regulatory but provide an official interpretation of and sometimes an historical background to the regulations.
The following 'Systems and Equipment Guide for Certification of Part 23 Airplanes and Airships' may provide some clarity for your question.
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023-17C.pdf
See page 282
- Kyrilian
On Jul 31, 2013, at 4:45 PM, "John Loram" <johnl(at)loram.org (johnl(at)loram.org)> wrote:
[quote] <![endif]--> <![endif]-->
Where would I find the FAA definition of “circuit essential to flight safety”?
Thanks, -john-
(get’n close to inspection)
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Robert L. Nuckolls, III
Sent: Monday, July 29, 2013 8:43 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: FAR 23 and airplanes of any stripe
…
Sec. 23.1357 Circuit protective devices.
…
(b) A protective device for a circuit essential to flight safety may not be
used to protect any other circuit. …
Bob . . . 01234567
8
[b]
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Fri Aug 02, 2013 6:37 pm Post subject: FAR 23 and airplanes of any stripe |
|
|
At 08:05 PM 8/2/2013, you wrote:
| Quote: | John,
The FAA publishes a range of Advisory Circulars that provide certification compliance guidance. These documents aren't technically regulatory but provide an official interpretation of and sometimes an historical background to the regulations.
The following 'Systems and Equipment Guide for Certification of Part 23 Airplanes and Airships' may provide some clarity for your question.
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023-17C.pdf
See page 282
|
On page 282 we read:
"After further review, FAA has concluded that the proposal should not be limited to airplanes that
operate above 25,000 feet since emergencies resulting in the loss of normal electrical power
are critical for all airplanes. Five minutes is considered adequate time to cope with such an emergency so
that pilot can operate the airplane safely and assess the reason for the loss of normal electrical power."
This seems to have been written by individuals
who've never sought the elegant solution to a
failure tolerant design, never flown an airplane
and been faced with a "five minuted window'
considered adequate for a pilot to put on his
mechanic's hat and "assess the reason for loss of
normal electrical power."
Okay, so assume he DOES correctly assess the
reason . . . now what? Whip out the toolbox and fix it?
Besides, what's 25,000 feet got to do with anything?
FMEA considers all anticipated operating conditions
from the ground up.
This is but one example of many pages of 'advisory
floobydust' for which the authors of such documents
are famous. After AC43-13 sat stagnant for dozens of
years and was being revised some years back. The FAA
'invited' the EAA membership to . . . uh . . .
help proofread the document.
I wrote about 12 pages of critical review on the
electrical section. Similar feedback was offered
by others who were highly skilled in their
disciplines. AC43-13 went back to the word processor
and didn't get released for another year or so . . .
for reasons beyond my understanding.
If they'd given EAA the thing in Word, we would
have had it cleaned up in a few days. The final
publication was better but was still sprinkled
with technical and practical inaccuracies.
Don't know who sat on the various committees
tasked with revising these documents but for sure,
there were no Bill Lears, Kelly Johnsons, Duane
Wallaces, Glen Rawdons, et. als.
My advice to any reader suggests that understanding
and mitigating the effects for loss of any piece
of equipment is stone simple. Just imagine how you're
going to get on the ground with that breaker
pulled. If you don't like the outcome of the
exercise, then fix it. It's not hard. Once it's
fixed, then you don't need a 'five minute assessment
window' . . . you flip to Plan-B and keep on
truck'n and you don't mess with the breaker.
Be wary of pronouncements from high places.
Our tax dollars pay millions of salaries,
benefits and retirement packages for individuals
who add no merchantable value to the general
welfare of domestic economy. The FAA is no
exception to the condition. Here's another
example . . .
http://tinyurl.com/mn55arc
Bob . . . [quote][b]
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nuckolls.bob(at)aeroelect
Guest
|
| Posted: Sat Aug 03, 2013 7:14 am Post subject: FAR 23 and airplanes of any stripe |
|
|
| Quote: | . . . AC43-13 went back to the word processor
and didn't get released for another year or so . . .
for reasons beyond my understanding.
If they'd given EAA the thing in Word, we would
have had it cleaned up in a few days. The final
publication was better but was still sprinkled
with technical and practical inaccuracies.
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I've not located my input to the EAA critical review
of the proposed revision to AC43-13 but I did find
a copy of Earl Lawrence's letter to FAA outlining
EAA recommendations
http://tinyurl.com/c5rm43k
. . . I believe that less than half of
my findings were included in Earl's letter
to FAA.
The significance of this activity resides not
in the details of errors noted but the shear
numbers of error and degree by which the
writers showed a disconnect with the technology
and processes over which they claim expertise.
These are all well meaning, gentle folks given
a job. But until you've successfully baked brownies
for millions of satisfied, repeat customers
and do it profitably in a free-market economy,
you are NOT qualified to write a specification
for the production of brownies in the uber-regulated
economy either.
When somebody determines that a specification
is needed, x-numbers of folks are given the
task, any y-numbers of folks are charged with
review and approval. From this policy/procedure
driven management style there is risk that
the work product will be vague, inapplicable
or cannot be complied with by any competent
baker of brownies or builders of airplanes.
Bob . . .
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barber_seville(at)msn.com
Guest
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| Posted: Sat Aug 03, 2013 7:39 am Post subject: FAR 23 and airplanes of any stripe |
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Hi Bob,
I read parts of the specification you highlighted at the end of this communication to my spouse and she said " that is beyond absurd ". And we wonder why our society is faltering.
Sent from my iPad,Chuck
“A nation can survive its fools, and even the ambitious. But it cannot survive treason from within. An enemy at the gates is less formidable, for he is known and carries his banner openly. But the traitor moves amongst those within the gate freely, his sly whispers rustling through all the alleys, heard in the very halls of government itself. For the traitor appears not a traitor; he speaks in accents familiar to his victims, and he wears their face and their arguments, he appeals to the baseness that lies deep in the hearts of all men. He rots the soul of a nation, he works secretly and unknown in the night to undermine the pillars of the city, he infects the body politic so that it can no longer resist. A murderer is less to fear.”
On Aug 2, 2013, at 10:35 PM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
[quote] At 08:05 PM 8/2/2013, you wrote:
| Quote: | John,
The FAA publishes a range of Advisory Circulars that provide certification compliance guidance. These documents aren't technically regulatory but provide an official interpretation of and sometimes an historical background to the regulations.
The following 'Systems and Equipment Guide for Certification of Part 23 Airplanes and Airships' may provide some clarity for your question.
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023-17C.pdf
See page 282
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On page 282 we read:
"After further review, FAA has concluded that the proposal should not be limited to airplanes that
operate above 25,000 feet since emergencies resulting in the loss of normal electrical power
are critical for all airplanes. Five minutes is considered adequate time to cope with such an emergency so
that pilot can operate the airplane safely and assess the reason for the loss of normal electrical power."
This seems to have been written by individuals
who've never sought the elegant solution to a
failure tolerant design, never flown an airplane
and been faced with a "five minuted window'
considered adequate for a pilot to put on his
mechanic's hat and "assess the reason for loss of
normal electrical power."
Okay, so assume he DOES correctly assess the
reason . . . now what? Whip out the toolbox and fix it?
Besides, what's 25,000 feet got to do with anything?
FMEA considers all anticipated operating conditions
from the ground up.
This is but one example of many pages of 'advisory
floobydust' for which the authors of such documents
are famous. After AC43-13 sat stagnant for dozens of
years and was being revised some years back. The FAA
'invited' the EAA membership to . . . uh . . .
help proofread the document.
I wrote about 12 pages of critical review on the
electrical section. Similar feedback was offered
by others who were highly skilled in their
disciplines. AC43-13 went back to the word processor
and didn't get released for another year or so . . .
for reasons beyond my understanding.
If they'd given EAA the thing in Word, we would
have had it cleaned up in a few days. The final
publication was better but was still sprinkled
with technical and practical inaccuracies.
Don't know who sat on the various committees
tasked with revising these documents but for sure,
there were no Bill Lears, Kelly Johnsons, Duane
Wallaces, Glen Rawdons, et. als.
My advice to any reader suggests that understanding
and mitigating the effects for loss of any piece
of equipment is stone simple. Just imagine how you're
going to get on the ground with that breaker
pulled. If you don't like the outcome of the
exercise, then fix it. It's not hard. Once it's
fixed, then you don't need a 'five minute assessment
window' . . . you flip to Plan-B and keep on
truck'n and you don't mess with the breaker.
Be wary of pronouncements from high places.
Our tax dollars pay millions of salaries,
benefits and retirement packages for individuals
who add no merchantable value to the general
welfare of domestic economy. The FAA is no
exception to the condition. Here's another
example . . .
http://tinyurl.com/mn55arc
Bob . . . | Quote: |
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st">http://www.matronics.com/Navigator?AeroElectric-List
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cs.com
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matronics.com/contribution
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[b]
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jonlaury
Joined: 06 Nov 2006
Posts: 336
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| Posted: Sat Aug 03, 2013 7:48 am Post subject: Re: FAR 23 and airplanes of any stripe |
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[quote="nuckolls.bob(at)aeroelect"]At 08:05 PM 8/2/2013, you wrote:
[quote]John,
snip....
Be wary of pronouncements from high places.
Our tax dollars pay millions of salaries,
benefits and retirement packages for individuals
who add no merchantable value to the general
welfare of domestic economy. The FAA is no
exception to the condition. Here's another
example . . .
http://tinyurl.com/mn55arc
Bob . . .
Initially, I thought this was a parody of government specification. When I realized that this is the real deal, I just found it positively scary that there are people capable of such inane gibberish. Even scarier that it has only been reviewed once in 26 years and STILL (apparently) passed muster as having value.
I'm sure that each of these cookies and brownies, made to spec, cost taxpayers about $636,947.53 each. Not to mention that the poor guys and gals out in the field, diligently trying to avoid being shot, are being poisoned by their gov't spec'd cookies full of hydrogenated oils (trans fat), enthroned as probably the worst dietary, cardiac health bad actor EVER!
No doubt that Donald Hamlin, Team Leader of this Alice in Wonderland, kafkaesque recipe/specification has found a career home in the industrial food sector, pumping out anti-nutrition, disguised as food by sugar and man-made palatables.
John
Do Not Archive
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sat Aug 03, 2013 8:07 am Post subject: FAR 23 and airplanes of any stripe |
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| Quote: |
Initially, I thought this was a parody of government specification.
When I realized that this is the real deal, I just found it
positively scary that there are people capable of such inane
gibberish. Even scarier that it has only been reviewed once in 26
years and STILL (apparently) passed muster as having value.
|
Absolutely. I have advanced this discussion at the risk
of upsetting readers for the injection of politics and
opinion from outside the framework of the AeroElectric-List.
I humbly submit that no opinion or politics are involved
here . . . just a simple acknowledgement of demonstrable
fact. The goal is to reinforce the idea that our airplanes
are collections of simple-ideas, recipes for success that
yield very well to common sense supported by experience
and lessons learned. I suggest further that notions of
'criticality' of electrical systems are hugely overblown.
Solutions for dealing with failure of systems useful for
comfortable termination of a flight are generally quite
simple.
If anyone is worried about any aspect of their projects
configuration or performance, bring it up on the List.
The sum total of talent and experience here far outweighs
anything one will find in the constellation of
'official' documents. You'll get answers here that
are understood as opposed to being dictated requirements.
Bob . . .
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