The FAA says that VAL radios cannot be installed in type certified aircraft because VAL do not have a production approval under FAR Pt. 21.
It appears that VAL mean to say that their radios conform to TSO, and that the FAR require them to conform to TSO, but don’t need to be approved, and hence could be installed, following the minor/major mod decision making process. This misses the FAAs point entirely (if this is indeed what they want to say)
What is the “production approval”?
Is it an organisational QA approval? Some years ago I looked into making a PMA part and you needed such approval for that. It was virtually impossible to obtain it for a company outside the US. Well you could do it, but you would have to host multiple FAA inspectors visiting, and it really was not viable for a small company.
It would not surprise me if you needed an organisational QA approval for making TSO parts, or parts claimed to meet TSO requirements. After all, you are issuing a CofC and (in theory) that has to be issued against a specific QA framework.
Peter, production approval and PMA are not exactly the same. PMA includes both design and production approval, but it’s not the only kind of production approval in existence. In particular, PMA is an approval for manufacturing of non-OEM parts. Also, if I understand it correctly, it is a “minor” kind of approval, which only applies to parts as opposed to assemblies or units of equipment – that is, PMA can cover production of pistons or hoses but not engines or radios.
Yes. PMA also means the part is a “legal direct substitute” for the original part. This can be airframe type limited, etc.
Interesting about radios… my project was making plug-compatible King autopilot servos 
