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 Post subject: Re: Electrickery.
PostPosted: Sat Feb 06, 2016 8:51 pm 
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Can I jump in here with a question about the actual topic?

While I agree with the gist of Neverblue’s assertion here about electrical loads needing to be considered, I do disagree with his interpretation of what is a specific, clear and concise question:
“Does the modification or repair alter an electrical generation device, or the electrical distribution system between the generating source and either its primary distribution bus, or any other bus designated as an essential bus?”
It would alter none of the items mentioned. However, yes, the handheld GPS installation would add a load to the system.

So, with regards to determining minor or major and what the certification requirements are in a scenario such as the hand held GPS installation that hoptwoit outlined, what is the standard or regulation that spells out the requirements for completing an electrical load analysis? 571 Appendix A doesn't address it.

I think it’s within the realm of reason to make an educated determination that, in the absence of other high load additions and modifications, a hand held GPS or a digital clock on its own isn’t going to push any generation or distribution system over the edge. Where though is the line drawn as far as having to do a full blown assessment of the electrical loads and of the generation and distribution system when installing something like this?
What if the customer simply wanted a second post light installed adjacent to an instrument? Can one simply be spliced in, or do we need to add that 40 milliamps to the calculation?



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 Post subject: Re: Electrickery.
PostPosted: Sat Feb 06, 2016 9:36 pm 
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Attachment:
AC43.13 11-35 & 11-36.doc [12 KiB]
Downloaded 11 times


Attached is some relevant information on this subject from "Acceptable Methods, Techniques and Practices".

Interesting discussion so far.



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 Post subject: Re: Electrickery.
PostPosted: Sat Feb 06, 2016 9:43 pm 
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The reference to do an ELA is found in AC43.13-1B, Paragraph 11-37, though it is brief. Cessna's maintenance manuals provide reasonable data. If you want a really thorough reference, I like this Australian AC:

https://www.casa.gov.au/sites/g/files/n ... 021c38.pdf

Your decision as to when you must do one will probably be based in your level of comfort in possibly having to explain to TC one day why you chose not to! Your reasoning might be good, and acceptable to TC, after the discussion. Perhaps it was easier to do and record the analysis! The fact that we might completely agree that there is a threshold below which it does not matter, still may not satisfy TC....



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 Post subject: Re: Electrickery.
PostPosted: Sun Feb 07, 2016 3:19 am 
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Location: Straight outta Dundarave...
Gentlemen ( & Ladies?):

I split the thread on G-meters as it was drifting into a discussion of electrical systems. The opening post in this thread, by NeverBlue, was the logical starting point for that split. NeverBlue had nothing to do with creating the split; further, the title of this thread: 'Electrickery', was my name choice, not NB's.

My apologies for any confusion this has created.

North Shore.


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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 6:06 am 
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Quote:
Quote:
(7) alter an electrical generation device, or the electrical distribution system between the generating source and either its primary distribution bus, or any other bus designated as an essential bus?

Information Note:

The electrical distribution system includes its associated control devices, and all its protection devices.


...just wondering how you answered no to this question?


THAT WAS THREAD DRIFT?????

:smt040

...and (7) says everything I need to know about what's major and what's not from an 'E' point of view.

It's not 5 paragraphs long attempting to explain it...with some sort of demented thought process.

CAR's is very clear to me...who has been doing avionics mods for over 25 years.

Never has it been acceptable to install anything directly off of the essential bus on a certified aircraft without approved data.

Imagine...someone could install 3 panel mounted radios off the essential bus and sign it out as a minor mod because they felt it was "within their level of comfort" that it's not going to affect anything really....
:shock:



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 7:27 am 
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Quote:
THAT WAS THREAD DRIFT?????


In a thread about G meter installation, which is entirely non electrical.... Yes. Probably the G meter OP gave up and left the thread out of frustration.

As the CARs are clear to you, excellent, apply them as you see appropriate to the work you do. As I said, you work in your world, I'll work in mine. I don't sign for avionics installations in certified aircraft.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 9:14 am 
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Different rules for different people.

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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 10:33 am 
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Different strokes for different folks I guess. Good discussion none the less.


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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 11:44 am 
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It doesn't matter if you delete my posts NS.

They have been recorded...
Your pattern is clear.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 1:04 pm 
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NeverBlue wrote:
It doesn't matter if you delete my posts NS.

They have been recorded...
Your pattern is clear.

Are you going to sue? I'm not sure I want to participate here if I'm at risk of being subpoenaed as a witness.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 1:12 pm 
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On the actual topic again:

“Does the modification or repair:
(8) reduce the storage capacity of the primary battery?”

Is this a backwards way of saying

‘Does the modification or repair increase the total anticipated load placed on the battery in the event of a power generation failure?’

or are they actually talking about installing a battery of lesser capacity?



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 1:29 pm 
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I think its a very awkward way of saying that it's a major mod if you are not still assuring the requirement for 30 minute run time on the battery, for the basic plane's systems.


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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 1:40 pm 
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Exactly right...which is why you can't simply hook something up to your primary...or in the case of many GA aircraft...the only bus.


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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 2:45 pm 
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Thanks for the references, torquey401 and PilotDAR.

43.13-1B gives criteria on determining if a change in weight and/or balance resulting from a modification or repair is negligible or not.

Is anybody aware of any such criteria given for determining that a change in electrical load could be legally considered to be negligible?

I’m not going to lose a minute of sleep over the post lights I’ve added, or other similar low milliamp increasing mods I’ve been involved with where no ELA was performed. However, it would be nice to have a nice black and white line, rather than the apparent all-or-nothing situation that exists where, as PilotDAR points out, you may find yourself having to make a case to a TC inspector who doesn’t necessarily see things the same as you do.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 2:50 pm 
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Quote:
7) alter an electrical generation device, or the electrical distribution system between the generating source and either its primary distribution bus, or any other bus designated as an essential bus?


Why would they reference physical locations if they were actually talking about the load on the generation device? This seem to be a standard that is only talking about where you can take power for a minor mod, not how much overall current you would be drawing if everything was turned on... that would read differently no? By not mentioning the impact on the capacity of the generating source they have eliminated it from consideration, otherwise there would be direct mention of 'current' 'voltage' or 'capacity'

If you read that and took a few amps off the main buss after the feed connection, how could somebody tell you you are wrong if you pointed back to that statement?

Blue isn't reading it literally, is reading it theoretically and adding his thought to make the text make sense. If you read it literally, if u don't alter the feed line between the generator and the buss, then you're golden. If you add a bunch of words tt don't exist in the CARS then you end up where blue is taking us.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 3:22 pm 
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Quote:
If you read it literally, if u don't alter the feed line between the generator and the buss, then you're golden. If you add a bunch of words tt don't exist in the CARS then you end up where blue is taking us.


Exactly.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 4:10 pm 
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I always forget about CAR STD 551. Subchapter D relates to electrical system loading. Also sections that relate to com and nav installations.

http://www.tc.gc.ca/eng/civilaviation/regserv/cars/part5-standards-551s-1810.htm#551_03



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 5:42 pm 
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They're talking about electricity!

You can't see electricity...........................



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 5:51 pm 
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Where do they say they're talking about electricity? That seems to be your assumption. They are talking about :

7) alter an electrical generation device, or the electrical distribution system between the generating source and either its primary distribution bus, or any other bus designated as an essential bus?

all of which are physical things you can see.

effectively, where they have not mentioned electricity, they have excluded it from consideration. Its like a multiple choice test, you would fail because in order to reach your conclusion you have to add information that isn't expressly stated. They could have easily written the statement to convey the conclusion you have reached, but the statement under debate says nothing about what you are contending.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 5:56 pm 
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Post removed, as was no longer relevant due to previous posts being removed.


Last edited by GyvAir on Tue Feb 09, 2016 9:45 pm, edited 1 time in total.

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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 5:57 pm 
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What you are saying then is if I wanted to change the physical location of my feed line from my alternator to the bus...like say down the right side instead of the left side...maybe even put a larger size conductor...with pretty heat-shrink labeling......

That's a major mod????



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 6:03 pm 
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I have no idea. I see this as a debate over semantics, under the paragraph we are debating, I would say yes, but your maintenance manual might be written in vague enough terms where you could get away with it. The question being, why would you need to do that in lieu of other modifications? LIke, what rational reason, other than in consideration of a major mod, would you have to change the physical routing of the feeder line? I have a hard time thinking of a situation, other than 'just for the hell of it' where you would be moving that line without other things going on.


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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 6:27 pm 
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Why???? That's it...why?

...because the sun rose in the east today.

Because the line was chafed and needed repair so I replaced it instead...



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 7:25 pm 
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NeverBlue wrote:
Why???? That's it...why?

...because the sun rose in the east today.

Because the line was chafed and needed repair so I replaced it instead...


But why would you change its location if you were doing a made repair?

If you're just replacing what's there with an equivalent, like a made part, that's definitely not a major modification. You change the route I think it opens up questions.



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 Post subject: Re: Electrickery
PostPosted: Sun Feb 07, 2016 7:47 pm 
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Quote:
If you're just replacing what's there with an equivalent, like a made part, that's definitely not a major modification.


Correct.

Quote:
You change the route I think it opens up questions.


Correct. Changing the location of a conductor can result in unintended EMI affects.

Is what was done to the aircraft a change to its design? Would the aircraft still conform to its type design following the "work"? If it is a repair, the next maintainer would see it (and perhaps not even notice, other than for a log entry), but in any case agree that the aircraft continued to conform to its type design following the work.

On the other hand, if the next maintainer sees something done to the aircraft which causes it to deviate from its type design, that maintainer will probably look for a log entry, and reference to the data used to support the work accomplished. Which might be an STC, or could be a copy of the completed Appendix A "test", and specified "acceptable data" for the work done.

I've been called well after the fact (18 years later once) to issue STC approval for work accomplished, which was determined (sometimes by by TC) to have been major, for which there was no approved data. A back to front approach, and risky.



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