STC's

[ScottK]

Could someone please explain how these work?

I found the list on the FAA website for our club plane (1968 172i) and there are quite a few. Everything from visors to seat belts to engine mods are included. As I understand it, these are for anything that alters the airplane from its original state. Is that accurate? And once it's on the list, does that mean it's approved for all similar models?

Any help would be appreciated.

 

[Stewartb]

STCs have AMLs (approved model list). STCs are approved data for major alterations so an IA can sign the mod off with the STC and return the plane to service. He'll file a 337 so the mod is attached to your FAA aircraft records. The STC must include a letter of permission from STC holder assigning the mod to your aircraft by N number or serial number.

 

[Clip4]

Any time a plane is altered, it must receive a field approval from the FAA. An STC is blanket FAA field approval for a specific product on specific aircraft. The FAA is basically saying this product will not negatively affect the aircraft and owners don't have to apply for a field approval before installing this product.

Any performance claims by the STC holder are not part of the FAA approval. So if the STC holder says our wing tips will increase cruise 10 knots, FAA is not certifying the performance claim.

An STC'd product may still require an certified mechanic to perform the alteration, some do not.

 

[bnt83]

Could someone please explain how these work?

I found the list on the FAA website for our club plane (1968 172i) and there are quite a few. Everything from visors to seat belts to engine mods are included. As I understand it, these are for anything that alters the airplane from its original state. Is that accurate? And once it's on the list, does that mean it's approved for all similar models?

Any help would be appreciated.

When a vendor has a great idea and decides to manufacture and sell modification components to be installed on type certificated aircraft such as a 172, they sell a lot better when they can show they have an FAA approval. You purchase the parts and data to install them. Mechanic or mechanic with inspection authorization just performs the work, inspection authorization conforms the work to the FAA approved data and returns it to service.

The STC is a data package containing the STC certificate (evidence of FAA approval), Approved Model List if applicable (applicability and which data packages apply to which aircraft), typically a Master Document List, associated drawings showing the alteration and installation instructions, Instructions for Continued Airworthiness, and possibly and Airplane Flight Manual Supplement. In short major alterations to type design require FAA approved data. STC is approved data, typically applying to specific makes & models listed in the STC's Approved Model List (if applicable).

There are other ways to get approved data, STC is just one way.

 

[flyingron]

Any time a plane is altered, it must receive a field approval from the FAA. An STC is blanket FAA field approval for a specific product on specific aircraft. An STC'd product may still require an certified mechanic to perform the alteration, some do not.

This statement is wrong in just about every aspect.

A field approval is not necessary every time a plane is altered.
An STC isn't a blanket field approval.
You can not use an STC without an IA involved. Whether he has to actually perform the work is no different than anything else.

Here's the actual situation.

Any time you make a MAJOR MODIFICATION to an aircraft (as defined by part 43 app A), you have to submit a 337. The 337 has to be submitted by an IA. With that 337, you have to have the basis for what makes the modification legal. An STC is that basis. If you have an STC, you comply with it and submit the STC (you must have specific authorization from the owner of the STC or the FAA won't take it). You submit it.

If you don't have an STC (or other already approved data), then you need a Field Approval. These are getting harder to get especially on big things like engines. There's no need for a field approval with an STC.


As pointed out the STC will specify what aircraft it can be installed on. Some are quite limited, others have approved models that go on for pages. If you aren't on the list, you still need the field approval because the STC doesn't apply to you. However, the FAA (well they used to), would consider the data on an STC to be pretty good if you could additionally show that it should apply to your aircraft safely.

All this covers approval of the modification.

There's a whole 'nuther can of worms with the approval of the part necessary to implement the STC or field-approved modification (or for that matter, changes in compliance with the type certificate or other things that are not major modifications).

 

[mkosmo]

Any time a plane is altered, it must receive a field approval from the FAA. An STC is blanket FAA field approval for a specific product on specific aircraft. The FAA is basically saying this product will not negatively affect the aircraft and owners don't have to apply for a field approval before installing this product.

Any performance claims by the STC holder are not part of the FAA approval. So if the STC holder says our wing tips will increase cruise 10 knots, FAA is not certifying the performance claim.

An STC'd product may still require an certified mechanic to perform the alteration, some do not.

Apart from the other generalizations that aren't quite correct, a field approval would imply that there's nothing else like an STC to support the modification, but I can see it being used as an analogy.

 

[bradg33]

You'll also notice that some companies get STCs for things that aren't actual major modifications, presumably because they think it helps the item sell better. Rosen Sun Visors are a perfect example. Barely a "minor mod" in most installs (typically uses the factory mounting holes).

 

[Clip4]

Apart from the other generalizations that aren't quite correct, a field approval would imply that there's nothing else like an STC to support the modification, but I can see it being used as an analogy.

Apart from the other generalizations that aren't quite correct, a field approval would imply that there's nothing else like an STC to support the modification, but I can see it being used as an analogy.

Actually, your statement totally incorrect. Just because there is something similar with an STC, does not require an owner to select that product over one without an STC.

To get a product STC approved, the process usually starts with someone getting a field approval for the modification.

 

[tinerj]

Not pickets seldom post first. They prefer for others to give the celebrated man in the street answers (that are essentially correct and easy to understand) so they can demostrate their superior intellect by picking it apart.

 

[mkosmo]

Actually, your statement totally incorrect. Just because there is something similar with an STC, does not require an owner to select that product over one without an STC.

To get a product STC approved, the process usually starts with someone getting a field approval for the modification.

Eh? A change requires a basis. That basis can be an STC. An STC was developed with engineering and/or flight data. I never said that an STC did anything about any other products?

 

[mkosmo]

You'll also notice that some companies get STCs for things that aren't actual major modifications, presumably because they think it helps the item sell better. Rosen Sun Visors are a perfect example. Barely a "minor mod" in most installs (typically uses the factory mounting holes).

And now we have to pay for an A&P to spend the time filling out the 337...

 

[Clip4]

Eh? A change requires a basis. That basis can be an STC. An STC was developed with engineering and/or flight data. I never said that an STC did anything about any other products?

No, you said a field approval implys an STC or similar product is not available. While the FAA would certainly guide one toward an STD'd product, a field approval does not mean an STC'd product was otherwise unavailable.

 

[mkosmo]

No, you said a field approval assumes an STC or similar product is not available. While the FAA would certainly guide one toward an STD'd product, a field approval does not mean an STC'd product was otherwise unavailable.

My apologies for my poorly worded statement: I was trying to say that the need for a field approval is only required if no STC (or other basis) is available for the installation.

 

[bradg33]

And now we have to pay for an A&P to spend the time filling out the 447...

You don't have to use the STC. A&P can just sign it off as a minor mod. In fact, it's arguably preventive maintenance (you could probably shoehorn a sunvisor into one of the interior categories).

 

[Stewartb]

FSDO is not supposed to do field approvals if an STC exists for the same mod. But it happens. Blanket field approvals were a different situation entirely and I don't know of any that are allowed these days.

 

[bnt83]

FSDO is not supposed to do field approvals if an STC exists for the same mod. But it happens. Blanket field approvals were a different situation entirely and I don't know of any that are allowed these days.

My whole radio job was a field approval put together by me despite being three STCs in the market for them.

 

[Checkout_my_Six]

lets back up a moment.....

When an aircraft is born....it first has a design approval....called a Type Certificate (TC)....then it's approved for production....called a Production Certificate (PC)....then it gets an airworthiness certificate at the end of the process.

After the aircraft enters service....when there are changes to the original TC......those are "supplemental" changes....called a supplemental Type Certificate (STC). Minor changes can be performed by an A&P with a log book entry....and "sometimes" a FSDO will grant a field approval using a 337 form if they "feel" data is presented to them that warrants approval. I'm not going to go thru and explain the TSO and PMA process....as there are those too....and amended TCs.

IMHO...the STC process is miss-used to gain an economic advantage and in many cases should be either nothing or TSO or PMA parts. I happened to belive that sun visors are a minor mod (not safety critical nor required equipment) and should be installed with just an A&P's signature....but they're not cause the manufacturers were able to convince someone at an Air Cert office to give them an STC....

 

[mkosmo]

IMHO...the STC process is miss-used to gain an economic advantage and in many cases should be either nothing or TSO or PMA parts. I happened to belive that sun visors are a minor mod (not safety critical nor required equipment) and should be installed with just an A&P's signature....but they're not cause the manufacturers were able to convince someone at an Air Cert office to give them an STC....

Agreed. Entirely non-structural change with no change to flight dynamics. Why the hell would that be considered major?

 

[MauleSkinner]

Any performance claims by the STC holder are not part of the FAA approval. So if the STC holder says our wing tips will increase cruise 10 knots, FAA is not certifying the performance claim.

While normally that's normally the case, there are STC holders who have gone through the process of getting improved takeoff and/or landing data approved.

 

[Clip4]

My whole radio job was a field approval put together by me despite being three STCs in the market for them.

At a lower cost than using the STC's owned by someone who would have charged you to use them.

 

[Stewartb]

Rosen wanted to sell airplane parts. That requires a PMA. The STC paves the way for others to purchase and install the parts with no questions about legal mumbo jumbo.

Atlee Dodge and Burl's aircraft both make STCd battery boxes for Cessnas. AC43.13-2B deliniates how the mod doesn't require any STC. Atlee's and Burl's take the burden of compliance off of the mechanic. Some guys appreciate that and are willing to pay extra for it.

 

[Clip4]

While normally that's normally the case, there are STC holders who have gone through the process of getting improved takeoff and/or landing data approved.

Yes, you are correct and changes are made to the AFM to document the performance increase for those STCs. One I love is an STC holder who claims, in part, better spin chacteristics and his STC is for an aircraft not approved for spins.

 

[Timbeck2]

So Scott...um, how's this thread workin' out for ya buddy?

 

[mkosmo]

Yes, you are correct and changes are made to the AFM to document the performance increase for those STCs. One I love is an STC holder who claims, in part, better spin chacteristics and his STC is for an aircraft not approved for spins.

"Intentional spins" prohibited I'm sure. While it may not be approved for intentional spins, it could improve the characteristics of inadvertent spins, right?

 

[flyingron]

After the aircraft enters service....when there are changes to the original TC.....
.those are "supplemental" changes....called a supplemental Type Certificate (STC)

No. A change to the type certificate just results in an updated version of the same type certificate.
A Supplemental Type Certificate is authority to make major modifications. It's not a supplement to the type certificate, it's a type certificate for a change the supplements what was in the existing type certificate.

Minor changes can be performed by an A&P with a log book entry....

Which includes changes that are in accordance with the type certificate. Actually, anybody authorized can make the change. For example, if I want to paint my plane red, I can do that myself and make the entry in the maintenance records myself.

and "sometimes" a FSDO will grant a field approval using a 337 form if they "feel" data is presented to them that warrants approval.

A 337 is a report of Major Alteration (and Repairs, but we'll leave that out). It's necessary for any major alteration whether you are doing it under an STC or via a field approval or via other means.
A field approval requires the consent of the FAA guy at the FIELD office (get it... field approval). An STC doesn't.

IMHO...the STC process is miss-used to gain an economic advantage and in many cases should be either nothing or TSO or PMA parts. I happened to belive that sun visors are a minor mod (not safety critical nor required equipment) and should be installed with just an A&P's signature....but they're not cause the manufacturers were able to convince someone at an Air Cert office to give them an STC....

I wouldn't call it a misuse. There's no reason that you use the Rosen STC. In fact, Mr. Rosen himself gave me the 310 paperwork when I bought the visors for the Navion because there was no Navion STC and we discussed that the 310 mouning hardware would work best.

I had it installed. Here's what you need:
1. Approved part: YES, Rosen has manufacturing authroity.
2. Approval to install in airplane: yes, minor modification.
3. Approved maintenance: yes, mechanic installed it and completed the log book entry and approved the aircraft for return to service.
The above three steps are what you need to do any time you make an installation or alteration.

 

[Clip4]

"Intentional spins" prohibited I'm sure. While it may not be approved for intentional spins, it could improve the characteristics of inadvertent spins, right?

You can probably make the claim spin characteristics in most SEL planes is improved by moving a quart of oil from the bagage area to the front. But it would not be a significant improvement.

 

[ScottK]

So Scott...um, how's this thread workin' out for ya buddy?

I think I'm piecing it together.

 

[mkosmo]

You can probably make the claim spin characteristics in most SEL planes is improved by moving a quart of oil from the bagage area to the front. But it would not be a significant improvement.

Sure, but now we're speculating about an STC. Are you knowledgeable enough with the STC in question and their testing to make any such claims? You never so much as mentioned what it was. Even something as simple as adding VGs would likely create a reasonable claim to enhanced spin characteristics.

 

[Stewartb]

I know a few airframe STC holders and their flight testing required high speed dives and spins.

 

[Checkout_my_Six]

Rosen wanted to sell airplane parts. That requires a PMA. The STC paves the way for others to purchase and install the parts with no questions about legal mumbo jumbo.

Atlee Dodge and Burl's aircraft both make STCd battery boxes for Cessnas. AC43.13-2B deliniates how the mod doesn't require any STC. Atlee's and Burl's take the burden of compliance off of the mechanic. Some guys appreciate that and are willing to pay extra for it.

Keep in mind......STCs can be sold....PMAs not.

 

[Stewartb]

An STC holder doesn't need a PMA if he installs the STCd parts in his shop. If he wants to sell airplane parts for installation by others he needs PMA approval. If the modification is or might be construed as a major alteration he'd get the STC to make the installation legal. Some guys will sell parts for field approval be the installing mechanic but I've never seen those parts have a PMA, so while they're sold as parts but can't claim eligibility as airplane parts. There may be some exceptions. Wait about 12 seconds and somebody will tell us all.

 

[Checkout_my_Six]

An STC holder doesn't need a PMA if he installs the STCd parts in his shop. If he wants to sell airplane parts for installation by others he needs PMA approval. If the modification is or might be construed as a major alteration he'd get the STC to make the installation legal. Some guys will sell parts for field approval be the installing mechanic but I've never seen those parts have a PMA, so while they're sold as parts but can't claim eligibility as airplane parts. There may be some exceptions. Wait about 12 seconds and somebody will tell us all.

my point is ....If I apply for a PMA to make a wigget.....I can produce those parts....but can not sell my PMA business to another holder. However, if I apply for an STC...I can later sell you the STC bidness. This is why folks want the STC for their product vs. the PMA.

 

[bnt83]

my point is ....If I apply for a PMA to make a wigget.....I can produce those parts....but can not sell my PMA business to another holder. However, if I apply for an STC...I can later sell you the STC bidness. This is why folks want the STC for their product vs. the PMA.

In other words a lot of approvals are not transferable. That's aviation in general including ops, not just manufacturing etc.

 

[Checkout_my_Six]

In other words a lot of approvals are not transferable. That's aviation in general including ops, not just manufacturing etc.

yup....

 

[Tom-D]

..but can not sell my PMA business to another holder.

Yes you can, the FAA can not stop you from selling any business.. Precision Airmotive just sold the entire production line of Marvel carbs to Kelly Aerospace. PMAs and all.
do your home work.

 

[JAWS]

my point is ....If I apply for a PMA to make a wigget.....I can produce those parts....but can not sell my PMA business to another holder. However, if I apply for an STC...I can later sell you the STC bidness. This is why folks want the STC for their product vs. the PMA.

I have no idea what this is supposed to mean. Please explain further.

Whelen makes Parmetheus LED landing and taxi lights. The actual lamps are PMAed. The PMA says they are a modification part. You need an STC to install them legally.
Lee Aerospace makes PMA King Air cabin windows. The PMA says they are a replacement part. You do not need an STC to install them.

https://en.wikipedia.org/wiki/Supplemental_type_certificate
https://en.wikipedia.org/wiki/Parts_Manufacturer_Approval

 

[Checkout_my_Six]

Someone thought there was enough of a design change from the original part that an STC was required...it had more features/functions than the replacement part...that's why not all replacement parts are just PMA'd.

Now if a holder is able to gain an STC in addition....it's financial a "better" situation for their business, cause one day they could sell the STC to another. PMAs are not transferable to another holder.

Honestly.....some of this comes down to ACO (aircraft certification office) shopping.

 

[Checkout_my_Six]

Yes you can, the FAA can not stop you from selling any business.. Precision Airmotive just sold the entire production line of Marvel carbs to Kelly Aerospace. PMAs and all.
do your home work.

the PMAs are not transferable....they had to "re-apply" for that approval.

 

[JAWS]

Now if a holder is able to gain an STC in addition....it's financial a "better" situation for their business, cause one day they could sell the STC to another. PMAs are not transferable to another holder.

Sorry, I still don't get it. Some how selling a PMA business is special, but selling an STC business is no big deal? Can you supply a reference?

 

[Checkout_my_Six]

you'll have to get into the orders in 8120....I'm not getting into that here.