Question about minor modifications

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frmech
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Question about minor modifications

Post by frmech »

Hi,

I am an apprentice trying to understand a bit more about the underlying regulations regarding modifications. Let's take for example a simple part, that is not explicitly certified (FAA-PMA, TSO) but that is made for the aviation market, geared more at experimental. Let's also say that this part has no effect on the TC, engine, aerodynamics and so forth. Please tell me if the following makes sense.

In the USA, such a part would be installed by filing a Form 337, using acceptable data such as AC43.13 for wiring or attachment, as well as the manufacturer's installation instructions.

In Canada, we don't have 337's. We have Minor modifications and repairs, and Major modifications and repair. Reading through Standard 571 Appendix A, which defines what constitutes a major mod or repair, I've determined this would be a minor modification (the major one requiring a report to be filled out).

Now, how would you actually go about this? Is it simply an entry in the logbook with details as to what data was used for the install? Is there Transport Canada approval required? A report to fill out? I can't seem to find any clear info on what to do if the repair/mod is NOT major.

Thank you all for the enlightenment!
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DonutHole
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Re: Question about minor modifications

Post by DonutHole »

I'm not sure that canada has "minor" modifications, I think it is either a modification or a major modification.

if you are completely sure it is not a major modification then you have two other concerns, scope and data. for a modification that is not considered major you can go with the lowest level of data, which would be acceptable data. Acceptable data covers a lot of ground, it can be advisory circulars, data from the manufacturer of the aeronautical product, data from the manufacturers of similar aeronautical products etc. when you quote this data in the release it should be very specific, the source and revision status of the manual should be in there along with all section, page, paragraph information and reference the page and figure number of any figures you use

Just make sure that though the modification may not be major, it might fall under specialized maintenance. if it is specialized maintenance it must be completed by a mechanic who has certifying authority under an appropriately rated amo
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frmech
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Re: Question about minor modifications

Post by frmech »

Thank you very much for the answer.

One case I was thinking of is a landing light flasher. It switches the landing light on and off at equal intervals (1 second on, one second off, for example). It goes in line with the landing light wiring and uses the original switch for control.

I would be tempted to say that this is not specialized maintenance, and I would quote the AC43.13 for wiring it (crimped buttsplices) and attaching it to the cowling. It does not come with instructions but it has 4 wires and a label: power in + and -, light + and -.

I don’t have access to more info, and I am wondering if more would be required. Is it up to the AME to make the determination that it’s enough? Or does TC need to be consulted on such cases?

Thanks again for your time
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photofly
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Re: Question about minor modifications

Post by photofly »

Per CAR571.07, your landing light flasher needs to meet "the standards of airworthiness applicable to the installation of new parts" which are in Standard 571.07.

It can either be a commercial part, a standard part, produced under an FAA PMA (with a release certificate), or manufactured in conformity with a part design approval issued by the Minister (see CAR561).

But if it's specifically designed for an airplane, and it's not a PMA part with an authorized release certificate or manufactured under a Canadian design approval, you may not install it on a Canadian aircraft other than an owner-maintenance or owner-built aircraft.
Let's take for example a simple part, that is not explicitly certified (FAA-PMA, TSO) but that is made for the aviation market,
You may not install such a part; you would be in breach of 571.07.

In this case it's not the process, or the modification, it's the actual part itself.
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Last edited by photofly on Thu Oct 24, 2019 9:29 pm, edited 1 time in total.
DId you hear the one about the jurisprudence fetishist? He got off on a technicality.
frmech
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Re: Question about minor modifications

Post by frmech »

Ok that clears it up then, it wasn’t super clear to me. So same deal with commercial parts I would assume.
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photofly
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Re: Question about minor modifications

Post by photofly »

frmech wrote: Thu Oct 24, 2019 9:29 pm Ok that clears it up then, it wasn’t super clear to me. So same deal with commercial parts I would assume.
Commercial and standard parts you may install. If you can find a landing light flasher that is an automotive part, fill your boots.
As an example, TC permits you to install a car engine heater in your certificated aircraft, as a minor mod:
https://www.tc.gc.ca/eng/civilaviation/ ... 37-548.htm
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Last edited by photofly on Thu Oct 24, 2019 9:32 pm, edited 1 time in total.
DId you hear the one about the jurisprudence fetishist? He got off on a technicality.
frmech
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Re: Question about minor modifications

Post by frmech »

Is there a logic behind that? How is an automotive part safer than a part made for experimental planes?
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photofly
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Re: Question about minor modifications

Post by photofly »

There is no logic.
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frmech
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Re: Question about minor modifications

Post by frmech »

Gotcha.
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photofly
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Re: Question about minor modifications

Post by photofly »

Well, except that aeronautical products are controlled: but if it's a commercial part then it's not an aeronautical product. Which sort of makes sense.
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frmech
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Re: Question about minor modifications

Post by frmech »

So really the only thing that makes this an aeronautical part: https://crewdogelectronics.com/collecti ... ht-flasher

Is that it says aviation landing light flasher?
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photofly
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Re: Question about minor modifications

Post by photofly »

This is one area where, unusually, the FAA rules are stricter than the TC ones. To install a "commercial" part on a US registered aircraft, the part has to be on an approved parts list:
https://www.faa.gov/documentLibrary/med ... _21-45.pdf
So really the only thing that makes this an aeronautical part: https://crewdogelectronics.com/collecti ... ht-flasher
Is that it says aviation landing light flasher?
It doesn't meet the definition of a "commercial part" which is:
“commercial part”, in respect of an aircraft, means a part
(amended 2002/03/01; no previous version)

(a) that is not specifically designed or produced for use as an aeronautical product...
That is clearly designed and produced for use an aeronautical product, so it can't be a commercial part.

The MAXPULSE flasher is available under an STC (https://www.aircraftspruce.com/catalog/ ... kkey=50115)
Installing it would therefore be a major modification, and the STC would be the "approved data".
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Last edited by photofly on Thu Oct 24, 2019 9:47 pm, edited 1 time in total.
DId you hear the one about the jurisprudence fetishist? He got off on a technicality.
frmech
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Re: Question about minor modifications

Post by frmech »

Thank you again for all those explanations, it’s very clear now. Cheers!
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torquey401
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Re: Question about minor modifications

Post by torquey401 »

You might be interested in the link below.

http://www.av8design.com/Topic_mods_home.htm
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Re: Question about minor modifications

Post by PilotDAR »

Refer to this criteria to make the Major/Minor determination for a Canadian aircraft:

https://www.tc.gc.ca/en/transport-canad ... a-1893.htm

If you determine it is a minor mod, and you have data such as AC43.13 which covers it, you're good to go.

All major mods require approved or specified data (STC)

Minor mods may be done IAW approved, specified or acceptable data. Though, it is still possible that a repair classified as minor, does not have applicable data of any kind, and you'll be back to having to have data approved (an STC/sSTC).

In the appendix, note (e) 9 & 10, they direct you to do an EMI test, which is described in AC43.13-1B, 11-106. Some electronic installations do affect instruments and radios, particularly LED light installations. It is also wise to verify GPS operation following wiring changes, where wires may have been routed close to both a comm, and a GPS antenna. I have tested aircraft where I have found cross talk, where a transmitting comm knocked out GPS reception. The frequencies to txmit on while observingthe GPS satellite signals are: 121.150, 121.175, 121.185, 121.190, 121.200, 130.285, 131.250, 131.275, 131.290 and 131.300 MHz.

Note that if your wire the thinking box for flashing landing lights to the avionics master, running landing lights while the av master is off will result in lights on but not flashing. 'Probably wise to power both from the main buss.
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boeingboy
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Re: Question about minor modifications

Post by boeingboy »

So - Here is a question.....My buddy wants me to install a Whelen Prometheus landing light in his Cessna 150. No problem (so I think) everyone is installing these. It is covered under an STC (which I don't understand as it really doesn't meet the criteria of a major mod) Again - no big deal.

However - when I was looking up the STC's included with the light there are 2 different ones. One covers the installation in helicopters and the other cover installation in fixed wing. The Helicopter one is on TC's approved STC list - but the fixed wing one is not. The install instructions and the ICA are identical for both. Is there a way to legally install this without the STC being approved by TC?
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photofly
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Re: Question about minor modifications

Post by photofly »

TC accepts FAA STCs without examination where the aircraft state of design is the USA (as it is for the 150) so you can use the FAA STC as your data and are good to go.

I will try to post a textual reference later.

If your aircraft is non US designed, it’s much harder.

EDIT: here it is...

Information Note 2 to Appendix B of SI 513-003
(https://www.tc.gc.ca/eng/civilaviation/ ... #appendixb)
FAA STCs applicable to Normal, Utility and Aerobatic Category airplanes, including VLA designs which were type certified on the basis of FAR 23 or equivalent standards, for which the U.S. is the State of Design are exempt from a type design examination, whether or not Canadian ATCs are implicated.
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Re: Question about minor modifications

Post by photofly »

boeingboy wrote: Mon Oct 28, 2019 11:39 am So - Here is a question.....My buddy wants me to install a Whelen Prometheus landing light ...It is covered under an STC (which I don't understand as it really doesn't meet the criteria of a major mod) Again - no big deal.
For a modern aircraft, 14 CFR 23.2530 requires
(d) Any taxi and landing lights must be designed and installed so they provide sufficient light for night operations.
That is an airworthiness requirement, so if you change the landing light characteristics, then you are doing something that "Significantly affects... airworthiness;" and hence is a major alteration (in FAA-speak).

Now the TCDS for the 150 lists the following certification basis:
Part 3 of the Civil Air Regulations dated May 15, 1956, as amended by 3-4. In addition, effective S/N 15282032 and on for 152 and S/N 681, A1520809 and on for A152, FAR 23.1559 effective March 1, 1978. FAR 36 dated December 1, 1969, plus Amendments 36-1 through 36-5 for 152 and A152 only. In addition, effective S/N 15285940 and on, and S/N A1521028 and on, FAR 23.1545(a), Amendment 23-23 dated December 1, 1978.
Trawl through whichever of those regulations are applicable to his airframe and see what they say about landing lights. (I've reached the end of my free research on this :-) )If nothing, then you could argue that the parameters of the light are not an airworthiness issue, and so it's a minor modification - no STC needed.

If, alternatively, the part is manufactured by Whelen under a PMA (Parts manufacturing approval) as a replacement for the lamp listed in your parts manual, then installation is merely replacing the lamp, and not a modification (in Canada) or alteration (in the US) at all.
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Re: Question about minor modifications

Post by photofly »

OK, I lied. Here's more free research.

here's CAR3 on the subject of landing lights:
§ 3.698 Landing lights. If landing lights are
installed, they shall be of an acceptable type.

§ 3.699 Landing light installation.
Landing lights shall be so installed that there is no dangerous glare visible to the pilot and also so that the pilot is not seriously affected by halation. They shall be installed at such a location that they provide adequate illumination for night landing.
Someone who knows more than me can comment on what is considered "an acceptable type" of light, but it's clearly an airworthiness issue.
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Re: Question about minor modifications

Post by PilotDAR »

I've done flight testing for both airplane and helicopter landing light approvals. "Acceptable type" should be interpreted to mean that a person appointed by Transport Canada/FAA must accept the light, and it's installation in the aircraft. It's a little subjective, but ultimately the result of a test somewhere along the line.

Understand that LED lights in particular are available with different beams, both spot and flood, or combinations. That creates an element for approval, as to what can be practically illuminated. For helicopters, it may be that one landing light must illuminate the landing area for both a normal landing, and an autorotation landing. The aiming will be important.

I'm not saying that this is terribly complicated, but there must be a record that these factors have been dispositioned appropriately.
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