tsts4
Pattern Altitude
When the parts were commercially built how could it have been a legal E/AB?
There is something I'm missing ?
It's possible. Both AC 20-27G and Order 8130.2J allow it, but both admonish that excessive use could render the project ineligible for certification under 21. 191(g). The Amateur-Built Aircraft Fabrication and Assembly Checklist provides the framework to determine the impact of using such assemblies.
IOW use too much and you end up violating the 51% rule.