On Friday, December 1, 2017 at 10:00:14 AM UTC-8, CindyB wrote:

There are recurring discussions about how much margin
designers provide for protection from this and that...

One of the more high-profile examples is this RV-10 airplane for which the amateur builder arbitrarily increased the gross weight by a hundred pounds. Designer Dick Vangrunsven rightfully took issue with this practice:

https://www.facebook.com/notes/vans-...37594966250883

...I am not in favor of flying beyond manufacturer's limits for anything...

That's the best plan!

--Bob K.