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nuckollsr(at)cox.net
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 Posted: Sat Jan 13, 2007 12:45 am Post subject: TSO's...and fuel level sensors |
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<snip>
Back to Aviation:
Rotax was at one time going to give customers the choice of purchasing a
certificated or non-certificated engine. By their own acknowledgment all
the engines were built in the same facility, on the same production line
and from the same parts. My recollection is that the cost of the paperwork
trail added 2 - 3 thousand dollars to the price of the certificated
engine. I would argue that the certification added no value.
In my experience, it's easy to SUBTRACT value by "certification".
Many rules that we're expected to meet were crafted with the idea
of establishing some minimum performance standards. But at the same
time, the bureaucracy surrounding the certification effort has become
so expensive that the kinds of testing we used to do as a matter of
course to validate our designs is minimized or even pushed off until
certification time so as to save on development costs. When some
failure occurs during qual, we look really incompetent in the
eyes of our bureaucratic examiners who can only respond by increasing
the numbers of examiners and hoops to jump through. We've lost our
IR&D mentality where there is freedom to fail inexpensively and to
accomplish all the non-certified, low-cost, engineering testing to
assure ourselves of performance before all the witnesses gather
with their microscopes. Instead of being a "floor" for performance,
certification has become a ceiling beyond which few managers want
to exceed for the sake of next quarter's bottom line. Engineers have
lost control of their destiny in a technology driven market.
Non-certificated avionics is not quite the same apple, because the OBAM
avionics manufacturers are not building any certificated units. This is a
"caveat emptor" situation. There is a lot of attraction for a GRT or AFS
EFIS for 25% of the cost of a certificated Chelton System. The
determination each of us potentially bets our lives and the lives of our
families on is that these manufacturers have done all the work that adds
value, reliability and durability without the accompanying NO value
paperwork. I am contemplating one of these two systems for my own plane,
but my decision will be deliberate and I will be test flying whatever
system I choose for quite a while before I depend on it in the clouds.
Yeah. There's also value in selecting systems that offer
perhaps 20% of the features of a certified system that
does 95% of everything we ever wanted the thing to do
but eliminates 80% of the risks due to a reduction in
the number of lines of code.
One area where I have a great deal of concern is the experience level of
the engineers at these companies. If a person is ignorant of items that
have already been discovered and addressed by TSO type testing, then that
person can actually believe that he is doing a terrific job, when he is
truly not doing "the best we know how." TSOs offer some protection that
known issues have been addressed. Without a TSO it then becomes our OWN
responsibility to determine that the purveyor of the avionics is not
ignorant of issues and has addressed them in his product design.
Exactly. I had a conversation with some folks this
evening who plan to bring some new software driven
hardware to the marketplace at OSH this summer. I
advised them to publish all their test plans, installation
manuals and operating manuals on their website. Start
a list-server unique to their product line and encourage
all customers and prospective customers to join it. There
needs to be very tightly coupled cooperation that
can only benefit the company by building customer
confidence and making sure problems are dealt with quickly
in front of the whole world.
A second concern I have is that new marketing features seem to be
frequently released. I don't know how well thought out and proven some of
these features are. My own preference is NOT to be a Beta site for the
avionics manufacturer. I am a forensic engineer and use an accident
reconstruction software that has had 14 new releases since December
2005! I would argue that every user of this software (Windows XP based) is
a beta site. The software is fabulously useful, but when it glitches I am
still sitting in my chair firmly supported by the floor. I would not want
to be using software like this at 5000' AGL in the soup!
It should be every designer's goal to increase the
value of their product and the temptation to add
features via software changes is exceedingly strong.
This is where the list-server can help the supplier's
managers decide what changes should be made and how.
I've been working an AP project where the hard-working
guts of the system holds GPS track to 1 degree of accuracy
and nothing more - 99% of everything you want an
autopilot to do. Less than a handfull of lines of code
in a $2 processor. ALL navigation bells and whistles are
offered as applications to run out of a hand-held.
The nav hardware sends "new course to make good" data
to the autopilot . . . and nothing more. If the bells
and whistles become troublesome, one can simply shut
them off without affecting the autopilot's stone-simple,
high-reliability task of keeping the dirty side down
and the pointy end aimed at your next waypoint.
I can't see any of the big name flight systems
folks taking this kind of approach. They'll consistently
dump all their tasks into one super-processor with
the attendant risks of having some whistle go off-key
and cripple the system's ability to do it's most
important tasks.
Only the OBAM aviation community can offer the close-
coupled supplier-consumer relationship necessary
to bypass bean-counters, process-and-procedure hacks
and certification inspectors so that a product may
evolve quickly in ways that benefit both the supplier
and the customer. The new paradigm is an information-
driven relationship between a capable supplier and
an informed, communicative customer. No amount
of regulation, certification or ISO9000 hat-dancing
can add value to an activity focused on capable and
willing suppliers offering the best they know how to
do to happy customers.
Bob . . .
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eschlanser(at)yahoo.com
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| Posted: Sun Jan 14, 2007 5:33 pm Post subject: TSO's...and fuel level sensors |
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[quote]Hey Bob,
Any more information available on the new AP system? Is it for the OBAM market?
Time: 12:45:07 AM PST US
From: "Robert L. Nuckolls, III"
Subject: Re: TSO's...and fuel level sensors
I've been working an AP project where the hard-working
guts of the system holds GPS track to 1 degree of accuracy
and nothing more - 99% of everything you want an
autopilot to do. Less than a handfull of lines of code
in a $2 processor. ALL navigation bells and whistles are
offered as applications to run out of a hand-held.
The nav hardware sends "new course to make good" data
to the autopilot . . . and nothing more. If the bells
and whistles become troublesome, one can simply shut
them off without affecting the autopilot's stone-simple,
high-reliability task of keeping the dirty side down
and the pointy end aimed at your next waypoint.
I can't see any of the big name flight systems
folks taking this kind of approach. They'll consistently
dump all their tasks into one super-processor with
the attendant risks of having some whistle go off-key
and cripple the system's ability to do it's most
important tasks.
Only the OBAM aviation community can offer the close-
coupled supplier-consumer relationship necessary
to bypass bean-counters, process-and-procedure hacks
and certification inspectors so that a product may
evolve quickly in ways that benefit both the supplier
and the customer. The new paradigm is an information-
driven relationship between a capable supplier and
an informed, communicative customer. No amount
of regulation, certification or ISO9000 hat-dancing
can add value to an activity focused on capable and
willing suppliers offering the best they know how to
do to happy customers.
Bob . . .
________________________________ Message 2 _____________________________________
Time: 12:21:04 PM PST US
From: "Terry Miles"
Subject: Wgt complexity and parts count vs running (+) wires
Bob,
I am looking at your example in the switch chapter on how I could use a 700
2-10 and wire Nav and Strobe lights. As I do this, I am mindful of keeping
things simple, but not at the risk of long power runs in the event of a post
accident short or loose wire or related risks.
I have an overhead switch panel in the Velocity I am building. When
possible I have tried to have those switches supply grounds (pin 85) to some
40 amp relays I got on Ebay from a Car Audio outlet that I will mount behind
the panel area.
The distance from the power fuse block to this o'head switch panel is about
8 feet one way. The load in question is a 1 amp (2 amp fuse) for the nav
light LEDs. (Not the strobe. It is fused at the control box.) Here is my
question.
Is there a good practices recommendation you might have given my choices are
an 8 foot run (+) power into my overhead panel over ground wire into the 700
2-10 switch that then requires two separate relays in nose.
Follow on question--if 1 amp loads (20awg) are OK, is there an amperage
break point where you would opt for remoted relays?
Thanks,
Terry
________________________________ Message 3 _____________________________________
Time: 01:23:38 PM PST US
From: "Robert L. Nuckolls, III"
Subject: Re: Wgt complexity and parts count vs running (+)
wires
At 02:19 PM 1/13/2007 -0600, you wrote:
| Quote: |
Bob,
I am looking at your example in the switch chapter on how I could use a 700
2-10 and wire Nav and Strobe lights. As I do this, I am mindful of keeping
things simple, but not at the risk of long power runs in the event of a post
accident short or loose wire or related risks.
|
Length of wire runs becomes a non-issue if the circuit is either
fused very lightly (5A or less) or is downstream of a DC power master
relay where it becomes "cold" as a result of preparation for landing
be it on or off-field.
| Quote: | I have an overhead switch panel in the Velocity I am building. When
possible I have tried to have those switches supply grounds (pin 85) to some
40 amp relays I got on Ebay from a Car Audio outlet that I will mount behind
the panel area.
The distance from the power fuse block to this o'head switch panel is about
8 feet one way. The load in question is a 1 amp (2 amp fuse) for the nav
light LEDs. (Not the strobe. It is fused at the control box.) Here is my
question.
|
We run power and control leads for distances as much as 50-60 feet
in some of our aircraft. As long as the wire gage is sufficiently
sized to offset voltage drop, there are no good reasons to add
relays EXCEPT to avoid having a LARGE switch in a row of otherwise
small switches or to avoid a LONG run of relatively fat wire (Larger
than 16 or 14 AWG).
| Quote: | Is there a good practices recommendation you might have given my choices are
an 8 foot run (+) power into my overhead panel over ground wire into the 700
2-10 switch that then requires two separate relays in nose.
Follow on question--if 1 amp loads (20awg) are OK, is there an amperage
break point where you would opt for remoted relays?
|
Do your math. 20 AWG wire is 10 milliohms per foot and drops
10 millivolts per foot per amp. Assume total wire in
2A nav light circuit from bus to lamp and back to ground is
say 25 feet. 20AWG will drop 10 x 2 x 25 or 500 millivolts.
As a percentage of system voltage, this works out to 500/14000
or 3.5% . . . generally considered quite tolerable. 5% max is the
rule of thumb. I'll suggest your lowest cost of ownership and
highest reliability will happen when relays are used sparingly and
the S700 series switches perform happily at 7A continuous and
satisfactorily at 10A.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
________________________________ Message 4 _____________________________________
Time: 01:54:32 PM PST US
From: Charles Brame
Subject: Crimp or Solder
I recently made up a BNC connector for an antenna lead. I have always
soldered the central conductor into the gold pin. My buddy suggested
that I crimp the connector rather than solder. I did, and it seems to
be okay. Crimping was certainly faster than soldering. What's the
approved method?
Today I was reading Bob's Aeroelectric Connection Chapter 18 on Audio
Systems. It showed a D-sub connector with all its little gold pins.
Again, I have always soldered Sub-D pins. Should they be soldered or
crimped?
I have made up many a Molex type connector and I've always crimped
its male/female pins. Would a drop of solder make them more secure?
Charlie Brame
RV-6A N11CB
San Antonio
________________________________ Message 5 _____________________________________
Time: 02:01:20 PM PST US
From: "Terry Miles"
Subject: RE: Wgt complexity and parts count vs running (+)
wires
Thank you, Sir.
--
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