That might be so, and it certainly would be prudent to comply, but it still doesn't make it mandatory.
Airworthiness is the responsibility of the FAA (in the US), and that's why we, and the manufacturers, pay millions and millions to go through the certification process. Once that's completed, FAA is responsible for the continued airworthiness of that particular type certificate, not the manufacturer. One can't have it both ways - either the manufacturer is responsible for the airworthiness (and in that case, why certify it?), or the FAA is.
Therefore, the only things that can make an airframe non airworthy is if the FAA published AD's or the STC's are not complied with or a licensed FAA representative (A&P/IA or FAA inspector) says so.
That might not be the case in EASA land, but I'm pretty sure it's similar.
Last edited by AdamFrisch; 18th June 2012 at 17:07.