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Need for start-up protection?
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fvalarm(at)rapidnet.net
Guest

Posted: Tue Dec 09, 2008 6:41 pm Post subject: Need for start-up protection?

I do think it MAY be for protection, secondly for convenience.  However, I

will have a backup switch in the form of "EBUSS" switch for redundancy.



Bevan

RV7A wiring based on Z13/8



--

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Dec 09, 2008 7:44 pm Post subject: Need for start-up protection?

At 08:37 PM 12/9/2008, you wrote:

 	  Quote: 	
		  



Bob,



I too have never understood the fear of a voltage "spike" during engine

start BUT, I always assumed  that while the average pilot may not know

what's going on here electrically,  he may have reason to be concerned just

the same.


	


   We TEACH people to be concerned. It's a primal force that

   sells a LOT of products! Just watch TV for an hour and count

   the commercials designed to instill fear of: getting old,

   hardening of the arteries, pressure in the plumbing too high,

   pressure in other plumbing too low, skin cancer, hydro-planing,

   home invasion, less than snow white clothes . . . you name it.

   In this case, we (at Cessna in 1968) didn't understand transistors

   and second-breakdown. It was assumed that "spikes" from the starters

   was killing our new hybrid vacuum tube/transistor radios.

   In fact, it was brown-out, not spikes that was killing the

   rather fragile, germanium power transistors in power supplies

   (the audio systems were okay).



   The Avionics Master was born there with siblings at Piper,

   Beech, et. als. 40 years later, we've learned to make products

   live with the ship's power as presented . . . but we neglected to

   un-learn a deeply held belief that has now morphed into an almost

   primal fear.

 	  Quote: 	
		     I always thought one could assume that during engine cranking,

the buss voltage would sag.  This sagging would "under power" the

electronics currently turned on, and it would be this extreme low voltage

event that would cause damage to sensitive things.  I call it a "brown out"

and many electronics don't like it. They malfunction in many ways. Sort of

like not knowing whether they're supposed to be off, or on, or...off,  no

on  etc.



In your experience, could this voltage sag for several seconds cause trouble

for some electronics (certified or not) in aircraft?


	


   Absolutely! One of the DO160 recommendations is that

   a product EXPECT brownout during starter inrush time.

   Here's what my last van did in the summer time, it's

   worse in winter:



http://www.aeroelectric.com/Pictures/Curves/95_GMC_Safari_1.gif



    Here's Dr. Dee's little red roller skate . . .



http://www.aeroelectric.com/Pictures/Curves/99_Saturn_SL1.jpg



    Here's a B400A Beechjet . . .



http://www.aeroelectric.com/Pictures/Curves/turbine_start_a.jpg



    All of these vehicles have electronics that in some

    cases is expected to perform during the brown-out for the

    purpose of getting an engine started. Other systems are

    allowed to complain but should recover gracefully after

    the brownout event passes. Graceful recovery is something

    that a number of OBAM aircraft equipment suppliers choose

    to forego.



    Here's an excerpt from DO160 speaking to a suite of

    power interruption/brown-out tests for digital

    equipment qualified to various classifications.



http://www.aeroelectric.com/Reference_Docs/Misc_PDF/DO-160_Section_16_Excerpt_1.pdf



    The idea is that whoever has some notion of supplying

    equipment to virtually any alternator/battery DC

    system aboard vehicles has no excuse for not considering

    the demonstrable gremlins that need to be tolerated

    if not dispatched.



    All of my processor based stuff resets within milliseconds

    of having normal power restored. I'll be helping some folks

    with a suite of engine controls early next year. THIS system

    will have to operate through any transient event that does

    not drop below 6 volts . . . and recover gracefully for

    all events that drop lower. Not a big deal.



    Bob . . .

dale.r(at)cox.net
Guest

Posted: Tue Dec 09, 2008 7:50 pm Post subject: Need for start-up protection?

jon(at)finleyweb.net wrote:

 	  Quote: 	
		   Ok, then what is the answer?   I am one of the folks that just can't 

 understand why this is not a problem in cars but is in aircraft. Does 

 a car have a relay that disconnects all electronics during engine 

 start or are the components better designed or ???

  


	


Nothing that complicated.  An automotive ignition switch is a multi-pole 

device.  In the "run" position, it connects B+ to two terminals: 

"ignition" and "accessory".  When it is turned to the momentary "start" 

position, it disconnects B+ from the "accessory" pole.  Usually, 

everything that isn't essential to running the engine is connected to 

"accessory"; hence, the radio (and, often, the 

cigarette_lighter/accessory_power socket) drop out, until one allows the 

switch to spring back to the "run" position. Thus, no need for a check list.



HTH,

Dale R.

echristley(at)nc.rr.com
Guest

Posted: Wed Dec 10, 2008 9:28 am Post subject: Need for start-up protection?

Eric M. Jones wrote:

 	  Quote: 	
		   



 Your automobile doesn't require some "special" technique to get everything going. This is the classic "accident waiting to happen".



 The Air Force did a study of airmen where they turned on a red/green  indicator light and the airman had to push a button in response to the green light. In about three cases per-thousand, the very best airmen either didn't push the button when the green light turned on, or pushed the button when the red light turned on. This seems to be the performance limit of  for the best human brains. 



 So if you have to turn off the avionics before starting. You'll screw it up 0.3 percent of the time. This can be expensive, and unnecessary.



   

Exactly, Eric.  Years of training to work around a problem will never 
	


beat eliminating the problem in the first place.

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Dec 10, 2008 10:01 am Post subject: Need for start-up protection?

At 10:28 AM 12/10/2008, you wrote:

 	  Quote: 	
		  



Your automobile doesn't require some "special" technique to get 

everything going. This is the classic "accident waiting to happen".



The Air Force did a study of airmen where they turned on a 

red/green  indicator light and the airman had to push a button in 

response to the green light. In about three cases per-thousand, the 

very best airmen either didn't push the button when the green light 

turned on, or pushed the button when the red light turned on. This 

seems to be the performance limit of  for the best human brains.



So if you have to turn off the avionics before starting. You'll 

screw it up 0.3 percent of the time. This can be expensive, and unnecessary.


	


   Which presupposes that the reason for turning the avionics

   OFF in the first place is the magic wand that prevents

   expensive damage. In support of the study cited above, I

   can't tell you how many times I got into an airplane where

   the avionics master switch was already ON. Since the pre-flight

   check list doesn't say "Avionics Master Switch - Check OFF"

   then the electro-whizzies would already be ON when I started

   the engine. I'll suggest it's even more common than the

   3 per thousand events cited.



   Bottom line is that it doesn't matter.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

ftyoder(at)yoderbuilt.com
Guest

Posted: Wed Dec 10, 2008 1:03 pm Post subject: Need for start-up protection?

Bob,

I'm getting the impression you are fighting a Up Hill  battle.

However, the new plane I'm building will not have an Avionics Master Switch.



An Old Dog has learned a new trick!



Tim

---

dale.r(at)cox.net
Guest

Posted: Wed Dec 10, 2008 2:00 pm Post subject: Need for start-up protection?

Eric M. Jones wrote:

 	  Quote: 	
		   Your automobile doesn't require some "special" technique to get everything going. This is the classic "accident waiting to happen".

 ...

 So if you have to turn off the avionics before starting. You'll screw it up 0.3 percent of the time. This can be expensive, and unnecessary.

   


	




Umm, Eric,



   So - like - your proposed solution is ...?



Dale R.

rnewman(at)tcwtech.com
Guest

Posted: Wed Dec 10, 2008 6:01 pm Post subject: Need for start-up protection?

For those who are interested in having your EFIS , GPS, or Engine monitor up 

an running before engine starting and having them continue to run through 

engine start (without rebooting)  we sell a series of products that allow 

these products to be supplied with continuous and regulated power even when 

the battery voltage drops to 5 volts or less during engine starting.   The 

product line is called Intelligent Power Stabilizer and we demonstrated it 

at our booth at Oshkosh.    All the details of what it does and how it works 

are available on our web site.



www.tcwtech.com



Thanks,

Bob Newman

rnewman(at)tcwtech.com

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Dec 11, 2008 7:19 am Post subject: Need for start-up protection?

At 02:55 PM 12/10/2008, you wrote:

 	  Quote: 	
		  

<ftyoder(at)yoderbuilt.com>



Bob,

I'm getting the impression you are fighting a Up Hill  battle.

However, the new plane I'm building will not have an Avionics Master Switch.



An Old Dog has learned a new trick!


	


    I don't fight battles. Gave that exercise up about 20

    years ago when I went to work for OEM air-framers. One

    can only be true to one's craft. Study the simple ideas

    and how they assemble into useful inventions (good

    engineering). Be willing to share that knowledge and

    understanding (good teaching). But don't be discouraged

    because managers with power over project will have

    reasons for embracing alternatives (self preservation).



    It's interesting that I'm presently working on a project

    that I proposed to my management about 5 years ago to

    replace a piece of 1970 technology (4 x 4 x 6" box

    full of discrete components for $20K) with a new

    design (2 x 2 x 1" box, thimbleful of discretes

    and a microprocessor for $1K). We had the people,

    the facilities and the excitement to make it happen

    in-house. I had concurrence all the way up to the

    chief scientist.



    I'm brass-boarding the replacement product now as

    a consultant to a supplier. My milestone presentation

    on the project will be attended by many of those who

    opposed doing it in the first place. I'm betting that

    even if they remember my earlier proposal, they'll not

    be the least bit embarrassed. It's their position that

    we should stick to our "core competency" . . . assembling

    purchased tinker-toys into airplanes. There's no need

    to understand how the tinker-toys work!



    I'm finding that this attitude prevails throughout the

    general aviation industry. When I began working with

    GA about 1975, folks in those facilities knew more

    about my craft than I did. Many were my teachers.

    Now it's rare to find even the most rudimentary

    understanding of electronics at the OEM's.



    The point of this long story is to re-enforce the

    notion that there are folks with control of

    a project that don't cherish confidence that

    comes from understanding. The only path open

    is to cling to tradition and cover their #$$(at)#

    with lots of specs and requirements. If and when

    the project flops, they are guiltless as long as

    they produced the "golden requirements". It's

    up to somebody else to deliver to those requirements.



    It matters not that what they've asked for can not

    . . . or should not be done. Our brothers building

    airplanes are faced with many of the same

    decisions placed before the managers at BeePipCesMo.

    We can only be willing to share understanding. The ability/

    willingness of individuals to exploit that understanding

    is out of our hands. It benefits nobody for you or I

    to bring clubs and shields to the conversation.



    Bob . . .

marcausman

Joined: 08 Feb 2007
Posts: 70

Posted: Thu Dec 11, 2008 10:18 am Post subject: Re: Need for start-up protection?

This is an interesting discussion, and reflects on some of the main design decisions on our flagship product, the VP-200.  Flying is a lot about repetition and process. We are taught to do the same things and follow the same process on each flight. Essentially, you divide a flight into "sub-segments" like taxi, takeoff, cruise, landing and then execute a series of checks and procedures for each of those modes of flight. 



And that's how the VP-200 works - you configure it to turn things on and off, confirm configuration, and bring up checklist automatically for each mode of flight, for example.



In the case of turning things on, you can configure it to turn on the avionics automatically after the engine starts. The process is repeated with precision on each flight. No 3% chance of error. Of course, this is a separate discussion from whether the avionics can handle whatever the starting process throws at them. The point is, much of the process involved in flying is repeatable by the system so you can focus on actually flying the plane and critical tasks.

_________________
Marc Ausman
http://www.verticalpower.com "Move up to a modern electrical system"
RV-7 IO-390 Flying

ftyoder(at)yoderbuilt.com
Guest

Posted: Thu Dec 11, 2008 4:21 pm Post subject: Need for start-up protection?

I agree, I believe this attitude prevails throughout industry, not limited

to the general aviation industry.



Another interesting ramification is the "Not Invented Here" syndrome. My

father was a Roto Gravure specialist and Inventor, as manager of Formica

Corp. he was unable to get many of his inventions out of their R&D Dept.

without the dept. heads name being included on the application. As you

suggested, many are more interested in their personal status than doing what

is best for the company.



I'm learning allot following the AeroElectric-List, thanks to your,and

others, participation...



Tim

---

longg(at)pjm.com
Guest

Posted: Fri Dec 12, 2008 6:27 am Post subject: Need for start-up protection?

We are all enlightened by the process. It is however unavoidable that we

are using more $$$ avionics today on top of a system that was designed

too many years ago and has not kept step with other industries. It's

sort of like buying a 32" monitor for a 286 PC (remember those?). I've

got 30k + on the face of my panel and I should probably be concerned

about a motherboard designed back in the 30's. This is where we industry

has left us. We've got marketers and we've got engineers. The marketers

are freelancers and the engineers have their hands tied. 



It's time to get some of this cooped up engineering into the fundamental

systems of GA aircraft. You know the big guys have it. I look at the

electrical system in my Porsche and the one in my Lancair and that makes

my head itch. By today's standard the one in my Lancair could have been

designed by an EE freshman which got a "C" in class. Sure it works, but

it doesn't pass muster with what is available to industry.



So here we are, Garmin selling us $100k panels to lay on top of our $20

solenoids. Let's hope the wires don't touch. Oh yes, don't forget to

shut off those fancy gadgets before turning the key. 



gl



--

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Dec 12, 2008 8:07 am Post subject: Need for start-up protection?

 	  Quote: 	
		  It's time to get some of this cooped up engineering into the fundamental

systems of GA aircraft. You know the big guys have it. I look at the

electrical system in my Porsche and the one in my Lancair and that makes

my head itch. By today's standard the one in my Lancair could have been

designed by an EE freshman which got a "C" in class. Sure it works, but

it doesn't pass muster with what is available to industry.


	


   In what way? Can you help us understand how that box of

   plastic under the hood filled with microprocessors, relays,

   fuse blocks and sundry sensors reduces "hazard" to accessories

   that are powered from the system?



   Admittedly, the systems in many vehicles including

   aircraft have a lot of bells and whistles that go to

   convenience and gee-whiz features at the cost of

   ownership and increased complexity (read reduced

   reliability). How do they influence rudimentary

   performance that goes to risk of death by design flaw?

   Just because there are more parts that do more things

   does not automatically translate into improvements in

   critical performance (reliability).



   Your nail gun will become useless if there's no power,

   shortage of air, no specialized cartridges of nails, or perhaps

   a tiny broken part within. I have hammers that were used

   by my grandfather 60+ years ago. They still perform as

   designed when new. They also have exceedingly low risk

   of failure to perform. If the system in your car is

   the new gold-standard for power system design, there has

   to be a host of simple-ideas that support the notion.



   "Passing muster" is non-specific. What design goals were

   honored to craft the system in your Porsche as compared

   to design goals honored to craft the electrical systems

   in your Lancair?



   Check out DC power section of Mil-Std-704F at:



http://www.aeroelectric.com/Reference_Docs/Mil-Specs/Mil-Std-704f.pdf



   and tell us how the Porshe system exceeds or expands

   on those requirements and what benefit is derived on

   behalf of a DO-160 qualified accessory?



        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

tommuller2000

Joined: 14 Dec 2008
Posts: 1

Posted: Sun Dec 14, 2008 12:30 pm Post subject: Re: Need for start-up protection?

I have dual Dynons (D100 / D120) and the IC-200 com radio and faced the same issue.  Since I need the D120 engine information before startup and don't need the radio, I put most of my radios on the avionics master, but the Dynons on the primary master. Once the engine is running, I turn on the avionics master in the same checklist item as the strobes, position lights and (if needed) the landing lights.



Since it is also hardened, the Garmin 496 is on the primary master.  That way I can program my destination and check the weather without burning any avgas!  



I agree that system design is better than airmanship.  I tried to make my airplane as idiot proof as possible for the times when I am an idiot.  Adding unneccessary cockpit load merely detracts from safety.

_________________
Tom Muller
RV-9A, flying

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