Menu Sign In Contact FAQ
Welcome to our forums

Secondhand autopilot, and STC permission

An STC is pre-existing approved data, so resubmittal is not required as far as I’ve ever seen. The same is true for other approved data – you don’t for instance submit a copy of the relevant pages of AC 41.13 when doing a repair on that basis and filing a 337.

Obviously there would be and is a difference between FAA requiring by regulation that permission for STC use be granted, and FAA requiring that you prove to them that permission has been granted. I believe the latter goes beyond what FAA consider the scope of their activity – protection of data rights is done in the courts. It’s an interesting subject anyway.

Certainly the nice ladies in the Registration Branch in Oklahoma City would be totally disinterested.

Last Edited by Silvaire at 28 Feb 19:44

If you remember, NCYankee, I pointed out initially that if the written STC was specific to the aircraft serial number, then the avionics manufacturer had the owner and the IA of the equipment in a position where they couldn’t legally base the installation on that STC, as approved data. There’s no need to endlessly repeat the point.

Agree there is no need to repeat the point. The regulations are quite clear and your assertion that an STC has to be written to a specific aircraft serial number in order for a an installer to need permission is flat out wrong.

We used to install GPS units based on a field approval using an STC that applied to a different make and model. Garmin granted permission to use the STC data and in our installations we provided a copy of the permission to use it in the package sent to the FAA for the field approval. A copy was also provided to the customer. After the 337 was approved and the work was completed, a signed copy of the 337 was sent to the FAA for filing.

KUZA, United States

What I actually said was that “the written STC limitations drive the process” i.e. in the real world, with tangible result, because what’s explicitly written in the STC is the only FAA controlled data that the A&P IA can use as a basis for his 337 sign-off. Beyond that, FAA does not control or maintain records of STC holder approval for individual installations, so potentially the discussion becomes about phantom documents stored nowhere. And obviously I was not talking about field approvals, which would be a different topic.

Let’s say an engine analyzer is purchased through the mail from Aircraft Spruce, with installation covered on a great many aircraft types under an STC and associated Approved Model List. There is no communication between buyer and manufacturer. The buyer (and an A&P IA) then installs the thing in his plane and operates it for 5 years before totaling the plane in a taxi accident and selling the engine analyzer to another individual who installs it on another aircraft in the Approved Model List, in accordance with the installation instructions. The second owner never has any communication with the manufacturer either. Does anybody think the A&P IA mechanic who inspects that second installation and files the 337 with FAA is at risk of losing his mechanic certificate or IA (or any negative consequence) because he didn’t obtain manufacturer approval for the specific installation? How would they prove it anyway?

What actually happens is nothing, because nobody cares unless they have a financial stake, in which case their recourse would be the courts and a civil IP case. That takes a pretty big financial stake to generate any action. FAA does not control or maintain records of STC holder approval for specific installations, and so has no basis or motivation to act on anything. The FAA maintenance regulation system doesn’t actually operate at the level of fidelity that warrants any absolute “flat out” statement with respect to so-called intellectual property rights.

As a side note, many STCs (for instance my engine analyzer example) cover a great many types on which the item has never been installed, the manufacturer just writes longest list of types he thinks the FAA may accept. I just installed a (new) instrument under STC on my aircraft that I know has never been installed on that type before, because I am in contact with all the other owners on N-register and none of them have one, or have ever had one I wonder how aggressive the FAA would be in acting against the mechanic/IA over a used instrument installation on a type like that, where it was in fact the first ever installation, to protect the financial interest of the STC holder?

Last Edited by Silvaire at 01 Mar 01:40

Does anybody think the A&P IA mechanic who inspects that second installation and files the 337 with FAA is at risk of losing his mechanic certificate or IA (or any negative consequence) because he didn’t obtain manufacturer approval for the specific installation?

I think that is the strict interpretation of the regs as written.

Yes it does seem bizzare that the manufacturer (the STC holder I should say) should get a bite of the cherry every time the item changes hands. It’s IMHO a fundamentally unfair restrictive practice, not least because if/when the mfg goes bust or chooses to not issue permissions, the item becomes worthless and that is against pretty basic principles in that once you buy something it is yours to do what you like with. The permission should be implicit in the purchase price.

It’s a bit like the software argument where it is legal to hack a program to remove copy protection, for your own use, because the developer has no right to stop you enjoying it in perpetuity. That’s unless the sale is under a continuous licensing contract where you pay an annual fee (like Adobe and MS are going now) but then nobody with a brain and needing long-term operation will use such software.

Would it be legal for an STC to contain a clause that the item cannot be installed unless new or freshly overhauled by the mfg? I can’t see that either, because again it would become worthless if the mfg support ends for whatever reason. The FAA doesn’t allow aircraft to be grounded in that situation (whereas Europe does).

How would they prove it anyway?

That’s a different question

I have obtained permissions by email, as a one-liner from their Sales Dept, from e.g. Shadin or JPI (IIRC). No way would those emails have been retained in some special file by the mfg. In fact they prob99 lost them minutes later like a lot of people do And certainly not connected them with the aircraft.

Shoreham EGKA, United Kingdom

It’s better to do the right thing than do things right. The consequences are zero because I think the FAA actually does have some people with common sense, and a similar dislike of coercion.

The FAA regulations are intended to comply with the FAA Reauthorization Act of 1996 and include 21.120 and 91.403.

From PUBLIC LAW 104–264—OCT. 9, 1996, Federal Aviation Reauthorization Act of 1996:

Section 44704 is amended—
(1) by redesignating subsections (b) and (c) as subsections (c) and (d), respectively; and
(2) by inserting after subsection (a) the following:
‘‘(1) ISSUANCE.—The Administrator may issue a type certificate designated as a supplemental type certificate for a change to an aircraft, aircraft engine, propeller, or appliance.
‘‘(2) CONTENTS.—A supplemental type certificate issued under paragraph (1) shall consist of the change to the aircraft, aircraft engine, propeller, or appliance with respect to the previously issued type certificate for the aircraft, aircraft engine, propeller, or appliance.
‘‘(3) REQUIREMENT.—If the holder of a supplemental type certificate agrees to permit another person to use the certificate to modify an aircraft, aircraft engine, propeller, or appliance, the holder shall provide the other person with written evidence, in a form acceptable to the Administrator, of that agreement. A person may change an aircraft, aircraft engine, propeller, or appliance based on a supplemental type certificate only if the person requesting the change is the holder of the supplemental type certificate or has permission from the holder to make the change.’’.

If you read the STC documentation available on the JPI website, it includes as part of the STC information, the permission to use. In summary, the STC cover sheet states in part:

If the holder agrees to permit another person to use this certificate to alter the product, the holder shall give that person written evidence of that permission.

A copy of this certificate must be maintained as part of the permanent records of the modified aircraft.

The following supplemental page is included with the STC documentation:

Subject: Permission to use STC.
To Whom It May Concern:
J.P. Instruments holder of STC SA2586NM grants to the purchaser of the EDM-700 series (PN EGT-701) and the Classic Scanner (PN EGT-100) permission to use the STC.

So the installer of the second hand JPI system should simply complete their paperwork.

Note that if this or any appliance is installed on another aircraft, it is not required to use the STC to install it. However, the modification would have to be accomplished via a field approval using other “approved” data. The other data would have to be independently developed from the STC and essentially describe how the installation of the appliance meets all the relevant regulations for such a modification. Of course, the easiest route is to use the STC as it is provided for free. In the case of Stec STC, they provide a fair value for their permission to use their intellectual property, as they provide a complete set of drawings and instructions that apply to a specific aircraft by serial number and include the installation kit which contains all the necessary brackets for the specific installation. On a new installation, they charge exactly the same amount for the kit in addition to the other components which comprise the autopilot. IMHO, for understandable reasons including product liability and support, they only deal thru their dealer network which is required to have both the expertise and equipment necessary to install and support the autopilot.

An example that comes up with Bonanzas is a modification of an older aircraft to use the later version of the wing tips. A company developed an STC that approves the modification, You can pay the $300 or so for the STC and be done with it or you can hire someone to submit a field approval with your own data and get this approved. It probably will cost more to go the second route. IOW, effectively it is the use of the STC data that is protected.

KUZA, United States

I’ve just been reading elsewhere on the internet that, basically, all secondhand autopilots are worthless unless permission is obtained from the STC owner. Clearly this is not always true, as this thread shows.

We have such a huge amount of knowledge here on EuroGA.

I also wonder what happens in the scenario where the STC owner has vanished, or is not responding?

Is there any feedback on how much different firms (e.g. STEC, HBK) charge for the STC permission?

Shoreham EGKA, United Kingdom

Peter wrote:

Is there any feedback on how much different firms (e.g. STEC, HBK) charge for the STC permission?

From Century Flight Systems:

STC. Included with STC – Installation Manual; Pilot’s Operating Handbook; Airworthiness Certificate $ 1,675

Avionics geek.
Somewhere remote in Devon, UK.

I have heard from one US dealer:

Stec charges $2500 to reissue the stc. Ideally you get the AP from an identical plane so the PN’s are right and the hardware is right. But this often costs nearly as much as a new system when said and done.

And Bendix_King reportedly do not issue permissions at all !!!!!! Is that really true? It would make all used HBK autopilots completely worthless.

Presumably this “STC permission thing” is an issue only for a new installation of a used autopilot system. If you have say a KFC225 installed already, then you can swap every single part of it (having, for example, bought an entire used KFC225 system from somebody) and that’s fine. The only thing you would need an STC for, in theory, is if you wanted to replace the KFC225 with a KFC150.

There is an interesting angle here: if two different autopilot types used the same servos, you could just change over the computers, so you are not “installing a new system” But how many do? HBK changed their servos often, though I don’t know if they changed them every time (one would have to wade through the IMs).

Frankly, I don’t believe this restrictive practice is widely followed, especially with HBK whose position renders an alleged STC violation unenforceable since by not offering the option they are stating that it would have no commercial value to them.

And how would anybody find out?

Shoreham EGKA, United Kingdom

I don’t think in this day and age anyone would want to pay money to do a fresh install of any King autopilot system, with the possible exception of the TruTrak aka AeroCruise 100.

Keeping an already installed system running is, as you say, a different story. Luckily used parts are somewhat available with many planes being refitted with units like the GFC500.

EPKP - Kraków, Poland
Sign in to add your message

Back to Top