Adding a G5 require a 337?

[M20 Ogler]

It comes with an STC. But I want to make sure everything is good 

[philiplane]

Any STC product requires a 337, and in this case, a flight manual supplement too. Which comes as part of the G5 document package.

[JimB]

3 hours ago, philiplane said:

Any STC product requires a 337, and in this case, a flight manual supplement too. Which comes as part of the G5 document package.

That is not necessarily true. But in this case, the installation of a G5 would be considered a Major alteration and would require a 337. 

[EricJ]

5 hours ago, M20 Ogler said:

It comes with an STC. But I want to make sure everything is good 

What does your IA say?    His opinion is the one that matters.

[philiplane]

2 hours ago, JimB said:

That is not necessarily true. But in this case, the installation of a G5 would be considered a Major alteration and would require a 337. 

It's always true. An STC by definition is an alteration, so the only way to add it to the airplane is via a 337. An IA can't have an "opinion" about it, he's compelled to file the correct paperwork. And hopefully update the weight and balance, and the flight manual. 

Edited October 1, 2023 by philiplane

[EricJ]

1 hour ago, philiplane said:

It's always true. An STC by definition is an alteration, so the only way to add it to the airplane is via a 337. An IA can't have an "opinion" about it, he's compelled to file the correct paperwork. And hopefully update the weight and balance, and the flight manual. 

Not all STC alterations are major.   The Rosen sun visors are the usually cited example proof.   The Bowers legal interpretation seems to leave lot of room for maneuvering, and certainly doesn't say clearly that it's always required.

I asked an FAA rep about this and it got very handwavy (literally) when the Rosen visor was mentioned.   It got really muddy after that, just like the Bowers letter.

One threshold these days does seem to be whether an AFM is involved, which it is with a G5, so it'd probably be pretty bold to install a first one without a 337.   That said, installing a second G5 does not require an additional STC or AFM, so it has been done without an additional 337.

[M20F]

A 337 isn’t exactly complicated to file.  Why split hairs.  I love the internet in my opinion @philiplane answered this in the first reply.  Then we all like to debate silly stuff for 2+ pages after that (and my response will get the troops going). 

[EricJ]

Just now, M20F said:

A 337 isn’t exactly complicated to file.  Why split hairs.  I love the internet in my opinion @philiplane answered this in the first reply.  Then we all like to debate silly stuff for 2+ pages after that (and my response will get the troops going). 

If someone just wants an answer, then the first one will certainly always do.

[philiplane]

1 hour ago, EricJ said:

Not all STC alterations are major.   The Rosen sun visors are the usually cited example proof. 

ALL STC's are major alterations. Every one. That's why they are called Supplemental Type Certificates. "STC". The definition of an STC is  major alteration to the Type Certificate.

Rosen visors were originally STC'd. Now, some are approved under NORSEE. Not all, but some. I do like that some things formerly STC'd are now being moved into the NORSEE program. But G5's are not one of them.

But if you buy any kit that is STC'd, you are back in 337 land. Someday, the FAA will make sense of their approvals, but until then, we mere mortals have to build a paperwork mountain in order to remain on the good side of our Friendly Aviation Advisors.

Edited October 1, 2023 by philiplane

[EricJ]

13 minutes ago, philiplane said:

ALL STC's are major alterations. Every one. That's why they are Supplemental Type Certificates. STC. The definition of an STC is  major alteration to the Type Certificate.

Rosen visors were originally STC'd. Now, some are approved under NORSEE. Not all, but some.

But if you buy any kit that is STC'd, you are back in 337 land. Someday, the FAA will make sense of their approvals, but until then, we mere mortals have to build a paperwork mountain in order to remain on the good side of our Friendly Aviation Advisors.

This was the question being answered by the Bowers letter.   When the alteration is a major alteration it is clear that a 337 is required, when the alteration is not a major alteration, it is much less so, and this is covered in the letter.

A 337 is a record of a major repair or alteration.   I've not seen anything that says "major alterations or STC".    If the STC is not a major alteration, again the visors are an existence proof of the case, then it becomes much less clear.   If it is a major alteration, then the STC provides the approved data for the alteration that is required to be included in the 337. 

One source of confusion seems to be the difference in classification of changes in type design and classification of alterations.   AC 21-40A indicates that a minor change in type design may be major alteration, i.e., the levels of the two may not agree.   So even though "An STC is a design approval for a major change in type design", "...an alteration done in accordance with a STC would constitute a major alteration if it "might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness" or "is not done according to accepted practices or cannot be done by elementary operations." 14 C.F.R. § 1.1. Any such alteration would require the completion of FAA Form 337."  That's all from the Bowers letter.

If it is not a major alteration, as described in the letter, why would a 337 be required?   There is not uniformity of opinion on this, apparently even within the FAA.   That is not surprising since there is not uniformity of opinion on what constitutes a major or minor alteration, which is not surprising since there's a lot of subjectivity in the description and definition.   The regulations do say, though, that the installer can make that determination.   A conservative approach would certainly favor filing the form if there was doubt.    If all STCs were clearly major alterations according to the regs and definitions there would also be no doubt, but, unfortunately, this is clearly not the case.    

Since the regulations indicate that the person performing the work determines whether an alteration is major or minor, and there isn't agreement in the industry, or apparently the FAA, on how to treat an STC that is not a major alteration (but may or may not be a major change in type design), then I think the usual logic holds that the IA doing the work has the opinion that matters.   I think that's really always the case.    That's what they're there for.   Internet forums, not so much, but they can provide insights into the varieties of opinions that may exist. 

 

[philiplane]

"If it is not a major alteration, as described in the letter, why would a 337 be required?   "

Because it may be the only way to get installation approval for parts that otherwise are not eligible for installation on Type Certificated airplanes. This is the maddening part of the current rules. You can have an approved part, but no installation approval to install it on a particular aircraft. Most people don't seem to understand this difference. But I can explain it this way: you might have a nice Lycoming 210 HP IO-390 engine. FAA certified no less. But you can't install it on your Mooney M20J, without an STC. Even though it's essentially the same as the existing IO-360, and has the same power output of an existing IO-360 that is modified with the 210 HP high compression pistons STC (the helicopter version IO-360). Why did you even need an STC to modify that engine with these pistons anyway? It's in the Lycoming parts catalog, and it's less than a ten percent increase in HP, so it shouldn't need an STC, right? Clear as mud.

The G5 is different yet, because it's an electronic flight instrument that can replace more than one steam gauge. There are individual TSO's that each steam gauge meets, and Garmin certified that the G5 meets several of them. So it's different technology, which the FAA is still getting used to after 20 years of the glass revolution. Garmin basically side stepped the processes by just going for an STC. Which drives the 337, flight manual supplement, etc.

[PT20J]

This major/minor/STC/337 stuff has been debated forever. But to me, the simplest thing to do is just file a 337. It's only a piece of paper and if you file it no one will ever question it. It also provides backup documentation if the logbooks are ever lost. I just don't see a downside.

Skip

[jetdriven]

The downside is you can be deeming a minor alteration as a major alteration.  The definitions are fairly clear.  

[MB65E]

Garmin Didn’t even have a TSO at the time! That’s why I believe they needed the STC. Did the G5 ever receive a TSO? 

Silly me when for the Sandia 340A because it had the TSO. There was no STC for the Sandia because it met the TSO!!
-Matt

[PT20J]

1 hour ago, jetdriven said:

The downside is you can be deeming a minor alteration as a major alteration.  The definitions are fairly clear.  

If the FAA issued an STC then a 337 Is what most would expect. So Rosen has an STC for sun visors and suppose you install them. What is the harm done to anyone if you file the 337? Sure it’s silly. Sure it should be a minor mod. But the FAA decided to issue an STC, so why not just file the 337 and be done with it?

[wombat]

One thing to note. A Garmin G5 cannot replace more than one steam gauge.

One G5 can replace an attitude indicator.

One G5 (but not the same one that is replacing the attitude indicator) can replace a DG or HSI.

One G5 can replace a turn coordinator, but not if it is replacing an attitude indicator or DG or HSI.

You cannot use a G5 to replace an altimeter, airspeed indicator or vertical speed indicator.   Yes, the G5 can display the altitude, airspeed, and vertical speed on it, but you cannot use it to replace those instruments.

[JimB]

It has a lot to do with parts production. You can't sell non-standard parts (nuts, bolts, o-rings, switches, circuit breakers, etc.) without some sort of approval. Something like Rosen sunvisors aren't going to get a PMA since they aren't form, fit, and function identical to the original part, but they can be manufactured under the STC. But does that make it a "Major" alteration? If I am following Appendix A to Part 43, I'd have a really hard time classifying that as a Major. Would I so I don't have to answer nit picky questions from another IA at the next Annual or the FAA, sure. But that doesn't necessarily mean that I think it is a Major alteration. Don't mix the certification regulations of Part 21 with the performance regulations of Part 43. 

Whenever you are performing a repair or alteration you have to evaluate it to determine if it is a Major or Minor per Appendix A to Part 43 and the classification of repairs and alterations is really about data. If you classify it as a Major, you have to have data Approved by the FAA (field approval, DER 8110-3, STC, etc.). A FAA Form 337 is not always required depending on who is performing the repair or alteration. 

21.8 Approval of articles.

If an article is required to be approved under this chapter, it may be approved—

(a) Under a PMA;

(b) Under a TSO;

(c) In conjunction with type certification procedures for a product; or

(d) In any other manner approved by the FAA

[Cruiser]

STCs are not hard to write and they show attention to detail and thoroughness of aircraft maintenance and care. This would be noteworthy when the plane comes up for sale. Good detailed logs are an asset.   

[A64Pilot]

An STC by definition is Major, ANY change to type design is by FAA definition, so as stupid as it is, yes installing Rosen sun visors is a major alteration, not because of the work, but because the FAA issued an STC, installation of an STC Requires a 337, and a 337 Requires the involvement of an IA.

STC’s are sometimes issued as a work around when there is no other legal way, for example when Whelen first came out with the Parmethius LED landing light, the FAA had no TSO for landing lights, so how could you determine if an LED was legal as there were no standards? TSO = Technical Standing Order, it specifies performance standards etc for a standard part, like tires for instance, it’s what keeps you from putting tailwheel tires you buy at Northern Freight even though they look identical for example, because they don’t meet TSO, nor are they made by someone with a PMA. A part needs both as a min. An STC can skip those steps.

So the answer that the FAA would accept was that Whelen bought the STC from Floats Alaska that had them installing LED landing lights, so the Parmethius was originally sold with an STC with instructions for continued airworthiness etc as all STC’s are required to have.

As it was an STC, that by definition was a MAJOR which required an IA and a 337 to change a light bulb.

Which of course brought up the joke of what does it take to install a light bulb in an airplane.

[OR75]

Another thing to keep in mind is that a 337 requirement / non requirement is not related to the complexity or difficulty of an installation 

[Trimetric]

This is a good discussion.  I'm an A&P, hard in the books studying for the IA test.  I see some definite errors in thinking in some of the above comments.

First, everything the FAA does is covered by CFRs and not by woms (word of mouth, like we sometimes had in the military).  And in searching, I find nothing in writing that says an STC requires a 337.  Some have said - "an STC is by definition a major alteration".  I find this not to be true.  If that "definition" is in the CFRs, I can't find it so please let me know if you do.

A major alteration is defined in 14 CFR part 1 and further spelled out in part 43, Appendix A.  Nowhere do I see it written that an STC has anything to do with the concept of major/minor.

The Bowers letter, like many legal documents has to be read with extreme attention to detail.  This whole argument keys on one word in the letter (second main paragraph) - the word "certain".  Counsel Peter uses the word "certain" i.e. "certain STCs require the completion of an FAA 337" and I think that resolves the question right there.  Obviously, as we all know, applying an STC that involves a major alteration will absolutely require a 337 - not because of the STC but because of the major alteration.  And therefore, contrarily and logically, applying an STC that involves a minor alteration does not require further documentation than the aircraft log book.

If Counsel Peter had not used the word "certain" the story would be completely different and all STC applications would require a 337 instead of "certain" ones.

The second to last paragraph of the letter seems to contradict this and require the 337 but actually does not - "The person performing an alteration in accordance with an STC must comply with all the requirements of section 43.9".  And that makes perfect sense.  43.9 directs that "each person who (blah blah) alters an aircraft" make an entry in the maintenance record.  It further requires in paragraph 43.9 (d) that major repairs and alterations be documented per Appendix B where we find the 337.  Again, there's no mention of the term "STC".

So what do we learn? To me, the Bowers letter confirms what we already knew about documentation requirements for major and minor alterations and does not direct us to fill out a 337 just because we use an STC as data to make the alteration.  That makes perfect sense to me and that's what I plan to do going forward.  If it's a minor alteration, I'll reference the STC as approved data in the log book and not file a 337. Of course, the title of the form is in fact - "Major Repair or Alteration" and therefore by definition is not relevant for minor alterations as defined in 43 Appendix A.

Some have said, "just file the 337".  Ok, you could do that but IMO, you're wasting time and money, using the wrong form, and not properly doing the job as an IA if the alteration is clearly minor.  But if the alteration could be interpreted to be major, of course, file a 337.

Obviously though, many alterations we make to our airplanes are actually minor so they should be done by an A&P with a log book entry referencing "acceptable data".

Please let me know if you find I've got my facts wrong.  I think this is an important concept for all A&Ps and IAs to understand.  And I appreciate what everyone has written about this since it forced me to dig in the books.

Thanks -  John McClanahan, Atlanta

[Trimetric]

Additionally, regarding the question that started this thread about installing a G5, FAA Policy Statement PS-ACE-23-08 allows electric attitude indicators to be installed as a minor alteration if certain requirements are met.  You can find it by Googling "FAA PS-ACE-23-08".

Again, if it's a minor alteration, the 337 is not needed or appropriate.

Hope this helps -

John McClanahan, Atlanta

 

[LANCECASPER]

1 hour ago, Trimetric said:

Additionally, regarding the question that started this thread about installing a G5, FAA Policy Statement PS-ACE-23-08 allows electric attitude indicators to be installed as a minor alteration if certain requirements are met.  You can find it by Googling "FAA PS-ACE-23-08".

Again, if it's a minor alteration, the 337 is not needed or appropriate.

Hope this helps -

John McClanahan, Atlanta

 

Most likely you if you are going to install a G5, you're going to interface it with things that the original vacuum attitude indicator wasn't interfaced with( ie, GMU 11, GAD 13,  GTP59, etc, etc). Does that still fit the ACE-23-08 Policy Statement?

That Policy Statement came out in 2015, the G5 in 2016 for certified aircraft.

I'm all for simplification. The difficulty comes when you sell your airplane and you get an IA that does a pre-buy evaluation for a first time buyer and convinces him that this was not a legal installation.

Whether you need the 337 or not may not even depend on what the FAA says but in practical terms may depend more on the person combing through your logbooks. The 337 should take 10-15 minutes to type and send off. It keeps everything clean when it's time to buy or sell.

[EricJ]

2 hours ago, Trimetric said:

Additionally, regarding the question that started this thread about installing a G5, FAA Policy Statement PS-ACE-23-08 allows electric attitude indicators to be installed as a minor alteration if certain requirements are met.  You can find it by Googling "FAA PS-ACE-23-08".

Again, if it's a minor alteration, the 337 is not needed or appropriate.

Hope this helps -

John McClanahan, Atlanta

 

FWIW, I agree with everything you said in both posts.   I've been through all the arguments before as well.   At an IA seminar an FAA presenter was making the "STCs are major alterations" statement from the standpoint that if it's not a major alteration it shouldn't need an STC (which you and I clearly find counter examples for).   I raised my hand and asked about the Rosen visors, and is that a major alteration, because that has an STC?   Much handwaving and avoidance of the question followed, and he never did answer the question.   So my conclusion was the same as yours, that the first question is whether it is a major alteration or not, and that's what determines whether a 337 is required, not whether it has an STC or not.   There are some arguments that if the item requires changes to the POH, (e.g., in the form of supplements, etc.) that that constitutes a major alteration, but I've not seen regs for that, either.   There is also often confusion around major changes to the type design vs major alterations to the aircraft, which are two separate and distinct things.  An STC supports a major change in type design, but there are many examples that do not meet the definition of a major alteration to the aircraft.   This seems to be at least one source of the confusion.

Another controversial question around the G5s is if you install one, and pay for the STC to install it in a certificated aircraft, and then at a later date buy a second one to install in the same aircraft, do you need to pay for the STC again?   The wording in the first STC seems to cover multiple installations in one aircraft.   Somebody who noticed this that was installing a second G5 asked Garmin about this and got lots of non-commital handwaving, like some FAA people do around 337s for STCs that are minor alterations.

I think many of these things are just muddy by their nature and these sorts of controversies just go with the territory.   My philosophy is that if I am comfortable making an argument to a judge that "this is why I did it this way", then that's probably good.   Legal opinions from the FAA, like the Bowers letter, are golden since it's a pretty strong argument if you can say you relied on a legal opinion from the FAA to determine how to do something.

[OR75]

1 hour ago, EricJ said:

FWIW, I agree with everything you said in both posts.   I've been through all the arguments before as well.   At an IA seminar an FAA presenter was making the "STCs are major alterations" statement from the standpoint that if it's not a major alteration it shouldn't need an STC (which you and I clearly find counter examples for).   I raised my hand and asked about the Rosen visors, and is that a major alteration, because that has an STC?   Much handwaving and avoidance of the question followed, and he never did answer the question.   So my conclusion was the same as yours, that the first question is whether it is a major alteration or not, and that's what determines whether a 337 is required, not whether it has an STC or not.   There are some arguments that if the item requires changes to the POH, (e.g., in the form of supplements, etc.) that that constitutes a major alteration, but I've not seen regs for that, either.   There is also often confusion around major changes to the type design vs major alterations to the aircraft, which are two separate and distinct things.  An STC supports a major change in type design, but there are many examples that do not meet the definition of a major alteration to the aircraft.   This seems to be at least one source of the confusion.

Another controversial question around the G5s is if you install one, and pay for the STC to install it in a certificated aircraft, and then at a later date buy a second one to install in the same aircraft, do you need to pay for the STC again?   The wording in the first STC seems to cover multiple installations in one aircraft.   Somebody who noticed this that was installing a second G5 asked Garmin about this and got lots of non-commital handwaving, like some FAA people do around 337s for STCs that are minor alterations.

I think many of these things are just muddy by their nature and these sorts of controversies just go with the territory.   My philosophy is that if I am comfortable making an argument to a judge that "this is why I did it this way", then that's probably good.   Legal opinions from the FAA, like the Bowers letter, are golden since it's a pretty strong argument if you can say you relied on a legal opinion from the FAA to determine how to do something.

the G5 is very light and often replaces instruments or indicators that weight a few lbs !

1 lb change .... redo W&B ... POH entry