Garmin IFR GPS, STC, 337, field approval questions

[Cxt1067]

On a C-150, a garmin 300XL gps was installed, and along with it an annunciator and CDI. As per log entry, they were installed for IFR and testing was done. An IA reviewing the papers found no 337 associated with this installation, but only the log book entry. IA stated that if a placard is made for VFR only GPS is placed, no further paperwork needed. And if the GPS is to be used for IFR, 337 would be filed, flight manual supplement needs to be made, and field approval is also needed.
Why is field approval is needed for 300XL when Garmin states that permission granted to use STC?
Also if FA is truly needed, how does this work? Is it simple as IA sending documents for FSDO to sign?

 

[Ryan Klems]

The 300XL is from an earlier era, before manufacturers were generally getting wide AML STC's and providing pre-approved AFMS's. The 300XL doesn't have an AML STC, or an approved AFMS, so one would have to write an AFMS, and apply for a field approval. This was very common in years past, but not so much anymore, so you might be in for some fun. Personally I wouldn't bother, even as IFR approved you would be limited to horizontal navigation only. If you really wanted to have a full IFR GPS in your 150, a GPS 175 or GNC 355 would be a lot more utility, but certainly higher cost.

edit: I see Garmin does have an STC for an IFR installation of the 300XL in a PA-32, STC SA00640WI. If you can get a copy of the AFMS that would have gone with that STC, you can probably use that as the template for writing your AFMS and use that STC to assist in getting your field approval.

 

[Cxt1067]

The 300XL is from an earlier era, before manufacturers were generally getting wide AML STC's and providing pre-approved AFMS's. The 300XL doesn't have an AML STC, or an approved AFMS, so one would have to write an AFMS, and apply for a field approval. This was very common in years past, but not so much anymore, so you might be in for some fun. Personally I wouldn't bother, even as IFR approved you would be limited to horizontal navigation only. If you really wanted to have a full IFR GPS in your 150, a GPS 175 or GNC 355 would be a lot more utility, but certainly higher cost.

edit: I see Garmin does have an STC for an IFR installation of the 300XL in a PA-32, STC SA00640WI. If you can get a copy of the AFMS that would have gone with that STC, you can probably use that as the template for writing your AFMS and use that STC to assist in getting your field approval.

Thank you Ryan, this is very helpful. A FA is probably the cheapest option to have rnav at this point. It has a vor, loc, gs nav, providing other approaches. It would be an adequate combo in my view.

 

[Bell206]

Why is field approval is needed for 300XL when Garmin states that permission granted to use STC?

Did your IA check the aircraft file from FAA for a copy of the 337? Sometimes the file will have a copy were the owner copy was lost.

To your questions, the STC permission letter is a separate regulatory requirement. A field approval is needed if no other approved data exists for a major alteration which an IFR GPS install would be.

Also if FA is truly needed, how does this work?

The installer or owner assembles data for the install, enters it in Block 8 on the 337, then takes it to the FSDO for an ASI to review the data and approve it in Block 3.

Is it simple as IA sending documents for FSDO to sign?

Not really. It would be a bit more involved than that.

 

[Cxt1067]

Did your IA check the aircraft file from FAA for a copy of the 337?

Thank you Bell. FAA does not have it. Owner has a filled but not signed 337.

Not really. It would be a bit more involved than that.

IA quoted 10hrs for the AFMS alone. IA suggested it is not financial wise to do it due to the amount of work and it is an unsupported GPS by Garmin anymore. But it feels like a shame they had it installed tested for IFR and never finished. FA cost sounds way less than a panel upgrade. 1/15? 1/20? of the cost to have another IFR GPS installed.

 

[Bell206]

Owner has a filled but not signed 337.

Which is meaningless. Without the signatures in Blocks 3, 6, and 7 you have nothing.

IA suggested it is not financial wise to do it due to the amount of work and it is an unsupported GPS by Garmin anymore.

And I have to agree.

FA cost sounds way less than a panel upgrade.

Just a GPS upgrade. Field approvals are not a guaranteed thing with most not approved in this day and age. Sounds like your IA is on top of things. Work with him to find an economic solution for you. Best of luck and feel free to post more questions if you have them.

 

[Cxt1067]

Which is meaningless. Without the signatures in Blocks 3, 6, and 7 you have nothing.


And I have to agree.


Just a GPS upgrade. Field approvals are not a guaranteed thing with most not approved in this day and age. Sounds like your IA is on top of things. Work with him to find an economic solution for you. Best of luck and feel free to post more questions if you have them.

You are absolutely right. the MK300 nav com in the plane is inop. A used one 2k. Now I am thinking get a 430 and use 300XL as com 2. Does that sound like a better option?

 

[aggiepack]

No. I would not install the next old, (nearly) unsupported box. The GNC355 would be my budget choice. Otherwise look for an used Avidyne IFD440, usually a little less expensive than used Garmin 650 /650xi.

 

[Bell206]

Now I am thinking get a 430 and use 300XL as com 2. Does that sound like a better option?

I'd first determine if you need actual IMC capability in your 150. If so, I have to agree the 430 is also a legacy unit which would have be WAAS in order to be a standalone IFR install. Perhaps PM @Jesse Saint here as this is what he does for a living and might have a good economical suggestion for your requirement?

 

[bradg33]

There's a very particular (and somewhat streamlined) process for doing Field Approvals for non-AML IFR GPS units that have an existing single-model STC. Garmin's install documentation for those units contains a "sample" AFMS (which requires little to no revision) and a checklist for the IFR "checkout" that has to be documented per the FAA field approval guidance. You don't have to write an AFMS from scratch (and 10 hours to work with Garmin's "form" is bonkers). Garmin's STC permission is there to allow you to use that STC data as "acceptable" data to support your field approval request (if the STC were applicable to your actual airframe, the STC data would be "approved" data). I installed a GX50 about 6 years ago as a field-approved IFR navigator in my old Twin Bonanza. Was a very simple process, but it took the FAA a couple of months to approve my AFMS (for no particular reason).

But what you're going to find is that almost no A&P nor any avionics shop wants anything to do with a field approval, even if a straightforward and streamlined one. It's not hard, but it's a black hole with the FAA in terms of how long they'll take to actually review and approve the AFMS (which can be approved at the FSO level, doesn't have to do to the ACO like most field approved AFMS do). It does take some "administrative" (paperwork) time that most A&Ps don't like to charge for because customer's don't like paying for it. So to avoid that rift, they just avoid doing field approvals. Why spend the time messing around with something that is just going to make everyone upset in the process, vs. spending that time working on a "bread and butter" project (like annuals, etc.)?

All that said, YOU can do a lot of the legwork for the field approval if you have a cooperative A&P and the time/energy/inclination to get into the paperwork. Other than "custom," there's nothing stopping you from interfacing with the FAA directly to obtain the approvals you need, so long as your A&P will sign the necessary forms and cooperate with you. My A&P had almost no direct interaction with the FAA when I got my field approval (or when I got a later field approval for a G5 for an install in an aircraft not on the AML).

 

[mandm]

Field approval sounds scary but I think it’s just paperwork sent to the FAA? I had one done on mine for the new beacon, I don’t think anyone checked it and I never received any paperwork back. So what does that mean, I don’t know.

Get the GPS 175 or you can get one with a comm or adsb in/out, probably around 10-12k. I think it’d be worth it for the utility it provides.

 

[Bell206]

I think it’s just paperwork sent to the FAA?

Not really. In general, a field approval is where the local FSDO ASI reviews your data and approves it for use with a major alteration or repair. It just so happens you use the same form (337) for a field approval as you use to record a major alteration or repair.

 

[Cxt1067]

There's a very particular (and somewhat streamlined) process for doing Field Approvals for non-AML IFR GPS units that have an existing single-model STC. Garmin's install documentation for those units contains a "sample" AFMS (which requires little to no revision) and a checklist for the IFR "checkout" that has to be documented per the FAA field approval guidance. You don't have to write an AFMS from scratch (and 10 hours to work with Garmin's "form" is bonkers). Garmin's STC permission is there to allow you to use that STC data as "acceptable" data to support your field approval request (if the STC were applicable to your actual airframe, the STC data would be "approved" data). I installed a GX50 about 6 years ago as a field-approved IFR navigator in my old Twin Bonanza. Was a very simple process, but it took the FAA a couple of months to approve my AFMS (for no particular reason).

But what you're going to find is that almost no A&P nor any avionics shop wants anything to do with a field approval, even if a straightforward and streamlined one. It's not hard, but it's a black hole with the FAA in terms of how long they'll take to actually review and approve the AFMS (which can be approved at the FSO level, doesn't have to do to the ACO like most field approved AFMS do). It does take some "administrative" (paperwork) time that most A&Ps don't like to charge for because customer's don't like paying for it. So to avoid that rift, they just avoid doing field approvals. Why spend the time messing around with something that is just going to make everyone upset in the process, vs. spending that time working on a "bread and butter" project (like annuals, etc.)?

All that said, YOU can do a lot of the legwork for the field approval if you have a cooperative A&P and the time/energy/inclination to get into the paperwork. Other than "custom," there's nothing stopping you from interfacing with the FAA directly to obtain the approvals you need, so long as your A&P will sign the necessary forms and cooperate with you. My A&P had almost no direct interaction with the FAA when I got my field approval (or when I got a later field approval for a G5 for an install in an aircraft not on the AML).

This is very informative. I will see if I can find that "sample" AFMS. The IA made it sound like it has to be written from the scratch by him.

 

[Bell206]

I will see if I can find that "sample" AFMS.

You may also want to review that single STC associated with the 300 to see if your aircraft has a similar configuration. Or at least look over AC 20-138. Some older GPS units were certified under the original TSOA which required additional NAV capabilites to meet the IFR requirement.

Once you get a handle on the details for an IFR 300 install in your 150, you could contact your local FSDO and discuss the requirements with an Airworthiness ASI. That way you'll have a better idea what you and your IA will need.

While field approvals are still possible, things changed a bit around 2004 which narrowed the field approval process and gave the ASIs more latitide to decline their use. So its best to be on your A-game when making the effort.

 

[mandm]

Not really. In general, a field approval is where the local FSDO ASI reviews your data and approves it for use with a major alteration or repair. It just so happens you use the same form (337) for a field approval as you use to record a major alteration or repair.

Changing out a beacon light with 2 wires is a major alteration or repair? Recording the repair is more of a notification?

 

[Bell206]

Changing out a beacon light with 2 wires is a major alteration or repair?

Depends. But alteration only. However, that determination is made by the installer based on the appropriate guidance. However, some mechanics are 337 happy and fill them out for anything and everything. For example, some believe every STC requires a 337 yet not all STC alterations meet the requirements for a major alteration.

Recording the repair is more of a notification?

The sole purpose of Form 337 is to document/record major alterations or repairs to aircraft, engines, props, and appliances. The reason is that level of work changes the item's certified conformity.

Additionaly, alteration 337s are considered part of the aircraft permanent records which an owner is required to maintain and transfer with the aircraft when sold.

 

[rtonry]

Does anyone have a copy of the AFMS? Or the sample AFMS? I'm looking at doing a 300XL install, but haven't been able to find a copy. I found the STC at the end of the installation manual. So, I'm good there.

 

[Cxt1067]

I found it. Pm me.

 

[bradg33]

Generic one for the PA32:

http://www.integratedavionics.net/IAS/manuals/Garmin/GNC%20300XL/GNC300XLTSO_ApprovedFlightManualSupplement.pdf

 

[rtonry]

I found it. Pm me.

I don't seem to be able to pm. Perhaps I haven't posted here enough.

 

[Cxt1067]

I don't seem to be able to pm. Perhaps I haven't posted here enough.

Brad posted it. It's found the same one.

 

[rtonry]

Thanks @bradg33 and @Cxtfor the help!!!