Experimental Implications

Mtns2Skies

Final Approach
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Mtns2Skies
*This scenario is strictly hypothetical and is only a thought exercise*

So let's say I have an A&P that feels comfortable installing a GTX345 for me in my certified plane. The rub here is that Garmin has specified that GTX345's must be dealer installed and no avionics shop will . However, they're available on aircraft spruce for experimental aircraft. So let's say that I have a friend with an experimental aircraft and I tell aircraft spruce that the transponder is for his aircraft so they will actually ship me said transponder.

Is there anything keeping me from installing said GTX345 in my plane?
 
There is no legal requirement that a Garmin dealer install the transponder. It is a Garmin dealer agreement issue. I don't know if there is any difference between the one they sell for certified and experimental, but I don't think so. While I don't necessarily recommend posting what you did on a public forum, but that would be legal to do what you propose.
 
What's so magic about the Garmin transponder? Bunch of companies making those things.
 
My understanding is the experimental version will not come with the appropriate TSO paperwork. The device itself is the same, but does not carry the certification required to be legally installed into a certified aircraft. You might get away with it for a while, but if a mechanic ever discovers the non-TSO part installed in the airplane you may have an issue at a future annual or pre-buy.
 
*This scenario is strictly hypothetical and is only a thought exercise*

So let's say I have an A&P that feels comfortable installing a GTX345 for me in my certified plane. The rub here is that Garmin has specified that GTX345's must be dealer installed and no avionics shop will . However, they're available on aircraft spruce for experimental aircraft. So let's say that I have a friend with an experimental aircraft and I tell aircraft spruce that the transponder is for his aircraft so they will actually ship me said transponder.

Is there anything keeping me from installing said GTX345 in my plane?

99% sure If you buy a GTX-345 "experimental" kit from anywhere and a "certified" kit they will have the exact same part number on the label and there is no difference. This is true for the G5 display itself for sure, even documented on vansairforce that they get FAA/PMA G5 display when ordering the "experimental" kits.

For a while they were selling the GTX-335 certified kit over the counter with a GPS antenna, transponder, and the STC installation data so any rated person could install them, but Garmin excluded the 345 from this program.
 
Talking totally out of my rear end here, no professional knowledge, but this is the Internet so here goes:

It depends on your plane and your mechanic. If you have an expensive, complex IFR aircraft that is maintained by a busy shop that is a stickler for the rules, probably dumb to cut corners to save a few bucks. An illegitimate install could come back to bite you at resale or at annual. Don't put a bootleg Garmin in your new Cirrus SR22.

If you have a simple, inexpensive aircraft like a Cub or Citabria, and your semi-retired IA buddy signs off on the annual every year for 500 bucks and a case of beer, then odds are nobody ever digs into the logs hard enough to find the discrepancy.

Strictly hypothetical*, of course.
 
The experimental version is TSO'ed, and should come with an 8130.
 
There's a member of this forum that did exactly that a year or so ago. And no, it wasn't me. My IA wasn't excited about it when I tossed out the idea to him, but I wasn't really serious so I didn't push him at all.
 
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The dealer install is only required for warranty support.
 
To my knowledge only the transponder and ADSB-OUT must meet TSO requirements to be legal for use in the national air space system under part 91. If the "experimental" avionics are TSOd then they meet that requirement. I see no reason why other Non-TSO or even avionics marketed as experimental cannot be installed in most GA aircraft. Is it possible that some airframe manufacturer has imposed some limitation on the installation of non-TSO avionics? I suppose but not to my knowledge. Is it possible that an avionics manufacturer has said use of non-TSO avionics in conjunction with your TSO avionics is prohibited? That would not surprise me.

But, as I've said previously, I don't find regulatory language that indicates that the avionics (other than identification devices) must be TSO for part 91 operations.
 
When ours was installed the damn ELT antennae needed to be moved to pass all the tests. So maybe the only thing keeping you from installing it is the lack of proper equipment to fully verify its working properly?

So can a AP with IA sign off the same stuff as a IA that signs off avionics related jobs. Or put another way, will your A&P have the proper signing authority? Just curious...I have no clue. I thought there was some kind of difference?
 
Why would Aircraft Spruce not ship you the transponder? They'll take your money, not ask where you're using it, unless I'm missing something?
 
Why would Aircraft Spruce not ship you the transponder? They'll take your money, not ask where you're using it, unless I'm missing something?
They ensure that it's for experimental not certified before they allow you to buy it. Probably per their agreement with Garmin.
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Certificated version comes with STC which, by the book, requires a 337. The A&P can fill out and sign the 337 but it still requires an IA to sign block 7 to approve it. Can you put an experimental version, without STC, in a certificated aircraft? Well nobody is physically going to stop you. The real question is will an A&P do it and sign the books? You'd have to come up with a real good reason as to why one would. What's in it for the A&P? You may as well just install it yourself and sign it off with your own signature. Who's gonna ever know?
 
Is the installation a major alteration? That's the question an A&P has to answer. If the answer is no, then no 337 required. Most major shops want to charge major bucks so by default most of the work they do is "major." There have been a lot of 337s filled out and filed that could just have easily and legally been skipped.
 
For a non-ADSB transponder, minor alteration and no need for 337, but the FAAs position is that ADSB-out transponders are a major alteration and require a 337.
 
The GTX345 for TCd airplanes is a dealer only unit, which I've been led to believe is Garmin's method of keeping its dealer network happy and in business.

As was already mentioned, the ADS-B out equipment needs at least one 337 submitted that documents the installation. The mechanic signing this off may have trouble legally doing so if the experimental version that is used does not have an STC covering it.
 
In this case the 337 is required because of the STC. It really isn't about minor/major alteration. Rosin sun visors come with an STC, thus a 337 is filed. Major manufacturers do it this way just so all the bases are covered and nobody can come along afterwards and make claims that it wasn't done right. In the old days it was pretty straight forward what was and wasn't a major alteration. Then the nit-pickers came along. I have no idea where they came from.
 
To my knowledge only the transponder and ADSB-OUT must meet TSO requirements to be legal for use in the national air space system under part 91. If the "experimental" avionics are TSOd then they meet that requirement.


I agree with you but found an interesting take on the "TSO required for transponders" bit on another thread:

https://www.pilotsofamerica.com/com...certified-aircraft.104981/page-4#post-3121358

Edit: FWIW the notes on my ECHO ADSB unit says:
It is designed to meet the performance requirements of TSO-C154c, and is
compliant with FAR 91.225 and FAR 91.227 for operation in the National
Airspace System.
 
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Is there anything keeping me from installing said GTX345 in my plane?
No. It all falls to the installing mechanic. The only person who may have any other issue will be the IA who signs the next annual. Perhaps inquire with him prior? As to the ADS-B OUT recording requirements this is a separate issue from the xspndr install which per Part 91 only has to meet TSO performance requirements but not be TSO’d (91.215(a)). A vendor has no authority to dictate how you install their parts, unless you want to use their approved data.
In this case the 337 is required because of the STC. It really isn't about minor/major alteration.
FYI: as has been mentioned in other threads, an STC is only a design approval and is not a trigger to require an STC. It’s all about what is a minor or major alteration. Several examples of this have been posted on POA before to include one STC certificate that states the alteration is a minor alteration, i.e., does not require a 337. Each installation is unique in a number of cases to include Rosens, e.g., some require a 337 and some don't, as the actual visor install (mounting rails) is a minor alteration in some aircraft and a major alteration in others but use the same visors.
 
Call FSDO and ask what they think. Then ask your mechanic what he thinks. That’s all that matters. The rest is worthless chatter.
 
...FYI: as has been mentioned in other threads, an STC is only a design approval and is not a trigger to require an STC...

An STC is exactly what it says - a supplement to the type certificate applied to the specific aircraft and despite what is posted on POA it requires a 337. Now I agree that things such as Rosen visors or other items or accessories that are clearly not a major alteration shouldn't have an STC but this is the way the larger product manufacturers have decided to go about it just so everyone will shut up - but it didn't work, people still want to argue about it.
 
An STC is a marketing tool. A guy makes a PMA product and can install it as a PMA product. An STC allows him to sell it for others to install.
 
Wait, too muck Rye. I got that backwards. An STC allows the inventor to install the product. A PMA allows him to sell it for others to install.
 
Not quite. A PMA part means a part is identical, or considered functionally identical, with an approved production process, so that it can be installed on an aircraft without changing the aircraft's type design.

A Supplemental Type Certificate, OTOH, changes the aircraft's certificated type design. It may require additional parts from the STC seller (for example, a STOL kit), parts from another supplier (like an engine swap), or no parts at all (like the mogas STC). A STC can be a one time thing for one specific aircraft, or it can be sold for use by others.
 
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There are STCd parts available that don’t require an STC for us to install them but do require an STC and PMA for the manufacturer to sell them as airplane parts. Rosen visors are an example. With respect to the transponder in question? I’m pretty sure I know what FSDO will say if asked about that installation.
 
Found this on the interwebs and thought it was concisely written:

A technical standard order (TSO) part is a designation provided by the Federal Aviation Administration (FAA) to denote a part that has been deemed airworthy. FAA TSO parts must meet set out minimum performance standards for use on civil aircraft, and often are designed to replace an original part. For parts to be considered “TSO parts” by the FAA, they need to have both their design and production approved. When a part is approved to be a technical standard order part, the manufacturer may produce the part and able it as such. Despite this, it does not mean that the part is permitted to be installed onto an aircraft, as it must then be proven airworthy by the FAA for the specific intended model.

Parts manufacturing approval (PMA) refers to another designation given by the FAA to parts that they have considered airworthy. PMA parts are most often those that are for replacing an Original Equipment Manufacturer (OEM) part. The process of being awarded designation as a PMA part is fairly rigorous, as a PMA part is one that is considered “equal to or better than” the OEM that it is to replace. The process first entails having the FAA determine whether or not the part meets airworthiness standards. If the part passes this stage, it must then undergo inspection and then the part will have to have instructions for repair, inspection, and continued operational safety plans.

While both technical standard order and parts manufacturer parts refer to replacement parts that the FAA has considered airworthy, the two still have some distinct differences that set them apart. For one,
PMA parts must have sufficient documentation addressing where the part is to be used on the aircraft and will have a letter and packaging stating the same. With TSO parts, there is no direct indication required for where the part is installed. Further separating them, PMA parts are strictly tested to be the same or better than the part it is intended to replace. A TSO part, on the other hand, simply has to meet basic FAA requirements.

My layman's understanding is that the STC and AML addresses the red highlighted text, eg proves a TSO part airworthy for a specific intended model of aircraft. Not needed for PMA because the aircraft is part of the process. Is this correct?

My further understanding is that major vs minor alteration (and thus 337 vs log entry) is a separate judgement by the installer/approver based on a set of criteria in the definition for a major alteration; eg, does the part change weight and balance, affect flight characteristics, require structural modification, changes to electrical system, etc. I have heard the phrase "drop in" used to denote a part which involves none of the above and thus is a minor alteration, though I don't know if that is an actual official term or just shorthand. I assume an STC or PMA would sometimes address whether an installation is major or minor, and that a PMA installation could be assumed to always be minor unless specified otherwise.

Not providing any advice, just trying out my understanding after a year of reading and getting confused by it.
 
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*This scenario is strictly hypothetical and is only a thought exercise*

So let's say I have an A&P that feels comfortable installing a GTX345 for me in my certified plane. The rub here is that Garmin has specified that GTX345's must be dealer installed and no avionics shop will . However, they're available on aircraft spruce for experimental aircraft. So let's say that I have a friend with an experimental aircraft and I tell aircraft spruce that the transponder is for his aircraft so they will actually ship me said transponder.

Is there anything keeping me from installing said GTX345 in my plane?

There is ZERO difference between the Experiential & certified for the GTX-345, except for price and sales channel. Lots of guys "borrow" a buddies experimental N number to order the transponder. Aircraft Spruce just does a look-up to see the the N-number is real for the experimental.

Unlike other Garmin Exp later Certified components like G5's, G3X's, etc, the 345 is only certified, yet sold to experimental market and has the exact same software/hardware/installation process.
 
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The issue you will have is accessing the necessary data to install it. Garmin doesn't make the install manual, STC permission, ICA, AFMS or the software to configure the GTX345 available outside their dealer network. If you can find someone to provide it, great. That's typically the biggest hurdle.
 
The issue you will have is accessing the necessary data to install it. Garmin doesn't make the install manual, STC permission, ICA, AFMS or the software to configure the GTX345 available outside their dealer network. If you can find someone to provide it, great. That's typically the biggest hurdle.
Well, I've found the install manual readily available. Surely the experimental guys must be able to configure it on their own no?
 
Well, I've found the install manual readily available. Surely the experimental guys must be able to configure it on their own no?

You (arguably) need the current version of the install manual, not whatever version you can find via Google. The config software is more readily available, but may take a little digging to find. IIRC, it's the same software for the 335, which is an over-the-counter product.
 
Also note that the ADS-B component of the GTX345 changes the calculus a little on the need for an STC/337.
 
If you buy it from spruce, spruce will provide the installation manual.
 
I've always thought the FAA's enforcement of "STC Permission" (nee intellectual property rights of STC holders) was something ripe for a legal challenge.

If I install a thing per an STC, but the STC holder didn't collect their friendship fee and issue their permission, how is that any less airworthy?

I know, "you wouldn't download an IO-550..." but.. it's a thought exercise I've worked through a few times. I don't think the FAA want to be piracy police, they just want to make sure you remain in compliance with the STC they approved. Not sure that any ASI I tangled with would appreciate the distinction though.
 
I've always thought the FAA's enforcement of "STC Permission" (nee intellectual property rights of STC holders) was something ripe for a legal challenge.

If I install a thing per an STC, but the STC holder didn't collect their friendship fee and issue their permission, how is that any less airworthy?

I know, "you wouldn't download an IO-550..." but.. it's a thought exercise I've worked through a few times. I don't think the FAA want to be piracy police, they just want to make sure you remain in compliance with the STC they approved. Not sure that any ASI I tangled with would appreciate the distinction though.

I know this is a thought exercise, but. Before challenging the FAA on anything think through all the possible consequences. See Warbirds.
 
An STC is exactly what it says - a supplement to the type certificate applied to the specific aircraft and despite what is posted on POA it requires a 337.
And you are entitled to your opinion. But as I’ve posted on a number of previous threads the FAA guidance does not support that opinion. As I’ve stated before, Part 21 covers STCs and Part 43 covers 337s. Two separate rules for two separate processes. So not to rehash old threads perhaps a simple example will suffice:

STC SP00582NY
Listed on page 3 under the approved Limitations and Conditions of this STC is the statement below. As you can see the STC itself states no 337 required. So technically speaking if you were to complete a 337 it would not be in conformance with the available approved data. But that would be your call not to follow that data. There are a number of other similar STCs if you’d like to see another example.
https://www.mcfarlaneaviation.com/media/documents/doc-sp00582ny.pdf
upload_2021-8-10_13-13-5.png
Now I agree that things such as Rosen visors or other items or accessories that are clearly not a major alteration shouldn't have an STC but this is the way the larger product manufacturers have decided to go about it just so everyone will shut up - but it didn't work, people still want to argue about it.
I don’t know what you’re personal experience with the STC process is but this is not the case. Some vendors use the STC approval process to streamline their design/production approval for various reasons. Some vendors even use all three (STC, PMA, TSO) approvals to bring the same specific part to market. Concorde batteries are a prime example of this. And it falls to the Part 43 installation/installer to define which part approval to use.
 
My layman's understanding is [...] just trying out my understanding after a year of reading and getting confused by it.
Perhaps this may help. There are basically 2 methods for installing parts on a TCd aircraft: as a replacement part which needs to be an approved part per Part 21, or as a Part 43 alteration.

On the approved part side, a person/vendor who wishes to produce parts for TC’d aircraft must obtain a design/production approval for that specific part per one of several methods: STC (design only), PMA (design/production), and TSO (design/production). Some vendors use all three processes, some two, and some one depending on the part type and market they wish to pursue.

A TSOA provides both a design and production approval per one of the existing Technical Standard Orders which is a rather limited listing and does not provide a method for all parts. However, in addition to a limited use, a TSO does not give an installation approval to any aircraft as noted in your red text. The Part 43 installer must determine/obtain that installation approval whether through a logbook entry or minor/major alteration.

A PMA also provides a design and production approval and is required for each individual part to be produced. So if you want a widget for multiple aircraft models you would need to follow the entire process for each model which can be expensive. And given the PMA is model specific it also provides an installation approval unlike a TSO part that does not.

The STC is only a design/installation approval. So while you can get that design approved through the STC process, which is more refined than the PMA design process, the STC does not give you the approval to produce (Mfg) that part. Hence the reason you see STC holders using the PMA/TSO approvals to produce their STC designed parts. While that sounds confusing, the STC design process actually can have more benefits than the PMA/TSO design process. For example, given there are basically 4 different types of STCs, an AML-STC will allow a single baseline design approval to be used across multiple aircraft models and TCs which is a huge cost saving when compared to the PMA design process for each specific model.

Now on the Part 43 alteration side, the part needs no existing approvals as that is what the alteration sign off will provide. So in general, anything can be installed on a TC aircraft. Anything you want. Now whether that installation is considered a minor alteration, or a major alteration, or a major change to type design it is the Part 43 installer who determines what approvals are needed. However, when a major alteration enters into the major change to type design territory, only the FAA ACO/MIDO offices can grant that approval through the STC or ATC process. So you can see the STC process is rather unique and can be used to approve the Part 21 design of replacement parts, in addition to, provide the approval for certain Part 43 aircraft alterations.

It may appear a bit confusing to the layperson, but there are several methods to the madness which are pretty straight forward once you’ve ran through them a few times.
 
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