Our company has obtained a PMA approval for producing several avionics parts through Identicality by Showing Evidence of a Licensing Agreement with a FAA STC holder. Furthermore, the parts have been sold later on to several OEM which are not part of the initial PMA eligibility list. The OEM created their own STC to install these parts into their TCed products.
I am lacking on knowledge specific to changes – post PMA approval. To the best of my knowledge, the STC holder, helps us initially to get the PMA, is responsible for analyzing/ approving the minor changes in correspondence with the pertinent FAA ACO.
I would appreciate some guidance on these points:
1) Who determines if a change is minor or major?
PMA holder? STC holder?
PMA holder could determine the impact of the change on the part itself. however, only STC holder could assess the impact that changes brings on installation.
that brings the question, in case of design changes, shall the minor/major classification be analysed against all STCs that install these parts?
and eventually perform minor changes to STC in parallel to the change on PMA parts? as I assume major changes are excluded from this as they are requiring a new PMA application and approval.
2) In case minor design change is created and FAA approved in collaboration with STC holder that helps initially to get the PMA, what are the PMA holder’s responsibilities against other STC holders using the same parts?
3)Which FAA branch controls the airworthiness of the PMA parts? (MIDO or ACO?). And who is obliged to inform the FAA branch of changes to PMA parts? PMA holder? STC holder (initial part installer/subsequent) ?
4)The STC-Holder has responsibility for continued airworthiness of used PMA parts.
What are the normal practices and rules for continued airworthiness when upgrading the parts? For example SW updates!
Let me have a go…
Who determines if a change is minor or major?
At installation time, the A&P determines that AFAIK.
PMA holder? STC holder?
PMA is just a manufacturing approval on the basis of the part being identical or sufficiently so. It is nothing to do with whether installing the part is Major or Minor.
STC implies a Major Alteration. However just because an item has an STC does not mean installing it is a Major Alteration. Many STCs are generated for marketing purposes, because many A&Ps are afraid of sticking their neck out and making the determination, and adopt a position that without an STC no mod can be done. The Concorde battery STCs are one example.
The STC-Holder has responsibility for continued airworthiness of used PMA parts.
The STC (or a Field Approval for that matter) has to contain a section called ICA – instructions for continued airworthiness. It is then the responsibility of the installer and subsequent A&P work to comply with that.
For the rest you need to talk to an FSDO inspector – or preferably several because you won’t likely get two answers the same 
thank you Peter for your reply. for some reason I have not received any notification that someone comments on this post.
We are struggling as a PMA holder to define a way we could manage a design change to our parts. My question in other words… if our initial STC holder (the one was behind our PMA approval) approves the minor changes we do…we could produce a part with this new approved design data… I guess we are on the same page up to this point…..however,, could we ship these “new” parts to other STC holders that install our parts on other products? what’s the approval cycle? do we have to evoke a minor change to all STC that install our parts when we perform a design change??? that does not sound right.
I will see if I can get you another reply Anas86 but in the long run you need to speak to a US FSDO or a DER. This is a complicated and unusual situation for a non US company to find itself in. Years ago I looked at making a PMA product and found it virtually impossible to organise it, starting with hosting a delegation from the FAA for a number of days.
Notifications need to be enabled in your profile, plus you need to whitelist euroga.org with your email provider to make sure the emails don’t get dumped by spam filters.
