Electrickery

[NeverBlue]

(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?

Split from here: http://www.avcanada.ca/forums2/viewtopi ... 7&t=107359Sorry for the confusion. ~North Shore

[iflyforpie]

(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?

It's installed 'on' on the avionics bus, not 'between' the bus and the electrical generation device.

[hoptwoit]

(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?

Because I can read.

[NeverBlue]

there's no need to get smart...

you see, in electrical terms, you have altered the electrical system between the generating source and the primary bus. That is without a doubt...whether your inspector knows that or not.
E=IR...your I between your source and bus has changed.

you would not have altered it if you would've used the cigarette lighter as your power source.

[Strega]

you see, in electrical terms, you have altered the electrical system between the generating source and the primary bus. That is without a doubt...whether your inspector knows that or not.
E=IR...your I between your source and bus has changed.

you would not have altered it if you would've used the cigarette lighter as your power source.

interesting reasoning... the cig lighter must have its own magic source of electrons..

[NeverBlue]

interesting reasoning... the cig lighter must have its own magic source of electrons..

...no...the cigarette lighter has already been installed, certified (presumably) and is protected via a circuit breaker. Therefore it's max load has already been accounted for in the aircraft's electrical system and you are not altering the maximum expected current draw from the source.

[NeverBlue]

Anything you would install between the generator/alternator and the primary bus would be carrying the entire, or at least a very large, electrical load. The only "Instrument" I can think of which could carry this load would be an ammeter (shunt).

I'm sorry but your interpretation of the regs is completely incorrect.

I'll ask this then:

Is the installation of a kick-ass stereo with a huge sub-woofer powered off the avionics bus a major mod?

[PilotDAR]

Quote:
Anything you would install between the generator/alternator and the primary bus would be carrying the entire, or at least a very large, electrical load. The only "Instrument" I can think of which could carry this load would be an ammeter (shunt).


I'm sorry but your interpretation of the regs is completely incorrect.

Fine.... You work in your world, I'll work in mine!

I'll ask this then:

Ask away.... in a thread on that topic, without drifting this one.... Attempting to further change the topic of this thread does not support your assertions.

[CID]

NeverBlue, you really need to stop posting about certification.

Is the installation of a kick-ass stereo with a huge sub-woofer powered off the avionics bus a major mod?

If the "avionics" bus is in an airplane that is IFR approved then it's a major mod. In that case why on earth would you power a non-required, non-essential load like a stereo off an essential bus?

As usual you fail to identify the details of the discussion and the standards (in this case) and make very broad statements trying to prove a point. PilotDAR is absolutely correct.

NeverBlue, do you understand the difference between "acceptable" in the context of types of data defined in 571.06 as opposed to the dictionary definition? Do you understand the difference between regulations and standards? Do you know what "essential" and "required" means in the context of the design standards? Your statements really seem to cast a lot of doubt in this area.

I've stated this before....you don't seem to know what you're talking about when it comes to certification so you should really think twice before posting unless you don't mind appearing foolish.

[NeverBlue]

You can not increase a certified aircraft's primary power source's electrical load without approved data.

Better?

[crazyaviator]

An electrical load analysis or an actual load measurement , if it falls within regulations, should be sufficient data to increase the load no ?

[torquey401]

Neverblue. Please explain your reasoning. Specifically, why can't a certified aircraft increase the electrical load without approved data? I have installed comms, intercoms, lights, cigar lighters and various other things without refering to approved data. I have also installed alternator and battery mods that do require approved data. To me the difference is the first is a load and the second is on the source side. The OP about a gmeter install, from the cheap seats here, appears to be other than major. Just my .02, in the end it is up to the person doing and certifying the work what road to go down.

[NeverBlue]

The original ELA is part of the original Type Design no?

If you add anything it will change the ELA. If you change that it's a major mod.

IMHO...

[photofly]

You can not increase a certified aircraft's primary power source's electrical load without approved data.

Better?

Of course you can. Do you think Cessna supplied their aircraft with dual GPS, two nav/comms, DME and a Mode C transponder back in 1959?

[torquey401]

The normal loads must not exceed 80% of the source capacity. What is the point? The 80% rule is part of the original certification requirements and part of AC43.13. 80% of 100 amps is 80 amps. If a comm is installed that doesn't tip the scale over 80 amps, you are good to go as far as that part of the puzzle.

I am still not understanding.

[NeverBlue]

Of course you can. Do you think Cessna supplied their aircraft with dual GPS, two nav/comms, DME and a Mode C transponder back in 1959?

You can not put those in unless it is approved?

Why the heck would there be STC's for that equipment to be put in a certified A/C if it wasn't required?

[NeverBlue]

Torque. ..what you're talking about is the requirement for a load meter. If you draw more than 80% of generator capacity you need a load meter.
Nothing to do with installing new equipment.

If you change the load according to the type design you have to have that approved.

They're not going to allow just anyone determine if they're feed line is going to burn up or not...you must know what you are doing to determine that..."Approved Data".

[PilotDAR]

Adding an electrical load from the main bus on, might not be a major mod in certain installations. If it is not major, it is minor (determination of which is the intended use of the 571 Appendix A test). If it is determined to be minor, then data described in 571.06 as "acceptable" might be a suitable reference for the installation. That would include AC43.13, which includes information on determining electrical loads, and the capacity of conductors.

The design requirements (FAR Part 23, for example) are more rigorous in terms of electrical compliance of a modification/installation than AC43.13, which is the purpose of the application of Appendix A, to determine if the installer should be seeking data which is described as "approved" in 571.06 - which would include an STC (which I might issue). The demonstration of compliance for the electrical requirements required for STC issuance has more factors than need be "complied with" for a minor mod sign off.

Happily, these days, the replacement of older avionics, and some lighting, can result in very pleasing electrical load reductions, and that is good all the way around. I am regularly asked to STC approve survey and science electrical systems, some of which draw considerably more than the airframe electrical system can accommodate within its original capacity. This becomes particularly challenging when an aircraft with two alternators can carry the load when both are running, but not on only one. What happens if you're surveying along, and you loose an engine (and thus its alternator)? The other alternator tries to take up the whole load, and it too fails before the pilot can shed the load. for this, I insist on special automatic load shedding systems.

These auto load shedding systems are also required when the battery capacity of a single engine aircraft is close to the line. I've had electrical modifications where the ELA demonstrated that the capacity of the factory battery exceeded the required 30 minute [failed alternator] supply time by 25 seconds. That's not much to work with, to take up extra load, and to allow for pilot recognition of the failure, and manually load shed. These were found design compliant based upon functioning automatic load shedding systems, which relieved the pilot of that added duty.

Obviously, these systems were installed between a generating source and a primary bus, so were major mods in and of themselves, let alone the survey system they powered. STC required.

I have had many occasions when the major/minor decision was fuzzy, even when using the test. Often, the AME/AMO/Owner elected to have me STC approve the mod, rather than try to support a finding of "minor". Totally their choice. Though costly, I can STC approve minor mods, and doing so ends all arguments as to the mod possibly requiring approved data - now you have it.

Changing an entire electrical system, exactly in accordance with the parts catalog from 14 to 28 volt (or vice versa) is major, and requires an STC, because it alters the original aircraft between the bus and the alternator, even though it is also a factory system.

A much less clear trouble zone for AME's/AMO's is the wording at the bottom of every STC, and its implications (which can include electrical). It reads:

".... Prior to incorporating this modification, the installer shall establish that the interrelationship between this change and any other modification(s) incorporated will not adversely affect the airworthiness of the modified product."

That task is a tall order, and documenting that it has been thoroughly completed is more than just a brief statement. This is where the accumulation of electrical installations - even individually minor, or STC approved, can total to requiring a separate approval just to permit them to be co installed on the same aircraft. STC required, even if none in isolation was a major mod.

From the Appendix A test:

(10) affect instruments, or indicators that are installed as part of a system required by the approved type design?

EMI. If you said "no" to this, to declare the electrical change minor, and use AC43.13, you could still have an EMI affect. I've done the testing and seen that the poor positioning of a single wire, not at all associated with comm or GPS, none the less causes a GPS failure when the comm transmits.

I encourage the application of the Appendix A test as a means to legitimize a mod as minor - if it is. Our industry is not served well with the expense and delays associated with STC approval of mods which are not major. Transport Canada staff will respect more the use of a TC procedure, when it correctly employed - that helps everyone. But that places the whole evaluation task in the hands of the AME/AMO, as the use of the Appendix A test is a maintenance task, not an aircraft certification task. Correct interpretation and application of the test is important, as well as the determination of possible interrelationships of multiple STC's. On that topic, in an appropriate thread, we can discuss the unfavourable interrelationships between engine changes and STOL kits, and some combinations of Cessna wing mods STCs which AME's/AMO's should be aware of - 'cause they're signing for them!

[NeverBlue]

 Correct interpretation and application of the test is important,

Uh...yeah!

[PilotDAR]

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

Uh...yeah!

Are my efforts to present a thorough answer to the topic of the thread going by unappreciated Neverblue?