Supplemental Type Certificates

Alchemy

Partner, Ally, Friend
When replacing factory installed optional equipment with an aftermarket upgrade, is an STC always required?

For instance, today I found out that a plane I fly has an STC because the stock sun visors were replaced with aftermarket rosen sun visors. This resulted in no weight change, but the STC was still needed (some poor guy found this out the hard way after taking the plane to the FSDO for his CFI ride, had to get a special flight permit to ferry it back home for maintenance).

Does simply removing factory optional equipment require an STC, or is one only needed if new equipment is installed in it's place.

Also, when replacing a radio or other piece of avionics with the exact same make and model radio, what type of paperwork must be filed? Do you just need to get approval for the field alteration?

Thanks....
 

EatSleepFly

Well-Known Member
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When installing factory installed optional equipment with an aftermarket upgrade, is an STC always required?


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Can you clarify that? Sounds like one big oxymoron...


Anyways:

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21.113 Requirement of supplemental type certificate.

Any person who alters a product by introducing a major change in type design, not great enough to require a new application for a type certificate under § 21.19, shall apply to the Administrator for a supplemental type certificate, except that the holder of a type certificate for the product may apply for amendment of the original type certificate. The application must be made in a form and manner prescribed by the Administrator.

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Just because theres no weight change doesn't mean there shouldn't be an STC. I know for a fact that Rosen sun visors require one, because a few of the airplanes that I fly have them. If there is a weight change and/or its considered a "major repair or alteration", FAA Form 337 must also be filled out.
 

Alchemy

Partner, Ally, Friend
Right, so why do the sun visors require an STC. What makes them "major" enough to require one. What is the test that determines wether an STC is needed or a 337 form alone is enough.
 

EatSleepFly

Well-Known Member
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Also, when replacing a radio or other piece of avionics with the exact same make and model radio, what type of paperwork must be filed? Do you just need to get approval for the field alteration?


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Radios can typically be R&R'd by anyone who holds a pilot certificate because they are considered "Preventive Maintenance." The list of items considered "Preventive Maint." is under Part 43, Appendix A.

Here's a reference from FAR Part 43, Appendix A:

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(c)(31) Removing and replacing self-contained, front instrument panel-mounted navigation and communication devices that employ tray-mounted connectors that connect the unit when the unit is installed into the instrument panel, (excluding automatic flight control systems, transponders, and microwave frequency distance measuring equipment (DME)). The approved unit must be designed to be readily and repeatedly removed and replaced, and pertinent instructions must be provided. Prior to the unit's intended use, and operational check must be performed in accordance with the applicable sections of part 91 of this chapter.

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EatSleepFly

Well-Known Member
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Right, so why do the sun visors require an STC. What makes them "major" enough to require one. What is the test that determines wether an STC is needed or a 337 form alone is enough.

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Again, this goes back to Part 43, Appendix A. If an alteration or repair is performed that falls under the list of "major alterations" or "major repairs", you must proceed to read Appendix B of Part 43...


...Which basically says that each person performing a major repair/alteration must execute at least two copies of FAA Form 337 and give one to the aircraft owner and the other to the local FSDO within 48 hours of Return to Service. There's some exceptions and other stipulations, but thats the gist of it.
 

EatSleepFly

Well-Known Member
So, in summary:

STC: Required for approval to install aftermarket products on a certified aircraft. Also required under 21.113 (quoted above).

FAA Form 337: Required after performing major airframe or powerplant repairs or alterations. This includes changes to Weight and Balance (see below)...

This from Part 43, Appendix A:

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(a)(1)(xi)- Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

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Whew...hope that all answers it for you. Sorry if its a little repetitive. Its waaaaay past my bedtime. I'm probably going to read this in the morning and be like, "whaaaat?!", so someone please correct me if I screwed anything up!
 

Alchemy

Partner, Ally, Friend
Thanks EatSleepFly, I really appreciate the help man....just trying to cover all my bases for my cfi ride (*gulp*) tomorrow. Maintenance and alterations are probably one of my weaker areas since I don't have much (zero) experience in the owner/mechanic role.

I've read through the appendices of part 43. Sticking with my example of the sun visors, it's tough to say exactly why it was considered a "major alteration" since I don't know what went into installing them, but I'm guessing the installation involved welding or riveting of some sort, which therefore qualifes it as a major airframe alteration. Because of this, the airplane needs, at the least, an STC, and if that type of alteration is listed in 21.19, a completely new type certificate.

Now, back to the radios, and more generally, preventative maintenance.

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43.3(g) The holder of a pilot certificate issued under Part 61 may perform preventative maintenance on any aircraft owned or operated by that pilot which is not used under part 121, 127, 129, or 135.

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As a pilot renting an aircraft from a flight school, I do not qualify to perform prevntative maintenance since I am not the owner or operator of that aircraft. At least that's what the DPE on my commercial check ride told me.....

However, going by part 1's definition of an "operator"

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"Operate," with respect to aircraft, means use, cause to use or authorize to use aircraft, for the purpose (except as provided in 91.12 of this chapter) of air navigation including the piloting of aircraft, with or without the right of legal control (as owner, lesee, or otherwise).

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Based on this, I have a tendency to disagree with the DPE who administered my Commercial checkride......I am operating a plane anytime I am flying it, and as the operator am qualified to perform preventative maintenance per 43.3(g).


Anyone willing to offer up the last word on wether a pilot, renting an aircraft, can preform preventative maintenance and that aircraft?
 

xdashdriver

Well-Known Member
[ QUOTE ]
When replacing factory installed optional equipment with an aftermarket upgrade, is an STC always required?

For instance, today I found out that a plane I fly has an STC because the stock sun visors were replaced with aftermarket rosen sun visors. This resulted in no weight change, but the STC was still needed (some poor guy found this out the hard way after taking the plane to the FSDO for his CFI ride, had to get a special flight permit to ferry it back home for maintenance).

Does simply removing factory optional equipment require an STC, or is one only needed if new equipment is installed in it's place.

Also, when replacing a radio or other piece of avionics with the exact same make and model radio, what type of paperwork must be filed? Do you just need to get approval for the field alteration?

Thanks....

[/ QUOTE ]

Just to make it crystal clear what we're up against in this whole topic: The FAA is not consistent in its application of the FARs. Having said that, prepare to be confused.

Form 337 is used for Major Alterations and Major Repairs. Go ahead and read the list of things that Part 43 considers to be a Major Alteration, and then forget about that list. The FAA goes way beyond that list, in reality, in determining what is a Major Alteration. They claim that anything that is not original equipment in an aircraft (in other words, part of the Type Certificate Data Sheet) can only be installed if there is an STC or a Field Approval (one of the uses of Form 337). Which one you need depends on how Major your Major Alteration is.

For some things, the local FSDO can just do a Field Approval and you can be done with it (for example, GPS, Intercom and many other kinds of avionics installations).

For things which require more engineering (such as different engines, winglets, stuff like that) then an STC will be required.

Note that Form 337 will be used for all STC installations too, so pretty much anything that has changed on the aircraft is gonna have a 337 with it. Some will have STCs as well, some won't.

Anytime you permanently remove a piece of equipment from an aircraft, you need to fill out a Form 337. Any time you permanently add a piece of equipment to an aircraft, you need Form 337. I say "you", your shop will do this for you.

If you are replacing a part which is included on the Type Certificate, or on an STC which has been legally installed in the ircraft, then all you need is an entry in the maintenance records of the aircraft.

I'm not even gonna get into Parts Manufacturing Approval since the water gets consideralby muddier in this area.

I learned these lessons while we underwent 6 long months of trying to get our Kingair put on our 135 cert. Our Principal Maintenance Inspector considers himself to be THE authority on anything airworthiness related, regardless of what the regulations say, the aircraft manufacturer says, or even FAA engineers at the Acircraft Certification Office say. He knows best and made us jump through countless hoops to get the aircraft approved.

Hope this helps,

Ray

P.S. Form 337, when detailing a Major Alteration, becomes part of the permanent aircraft records and must be kept indefinitely. Form 337 when detailing Major Repairs, need only be kept for 1 year after the repair was made, and then is no longer required to be part of the aircraft maintenance records.
 
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