Originally Posted by
Bill Serger
In short, I am having a discussion with someone who feels the Loads defined in FAR 25.301, the factor of Safety in FAR 25.303, and the Strength and Deformation definitions in FAR 25.305 will provide a margin of safety for an aircraft which hypothetically would be accelerating through Vd+50 and pulling upward of 2-3.8g.
I contend no such margin exists nor is defined by Part 25.301, 303 and 305.
Additionally, the margins required by regulations - whether for loads or for anything else - are not there to be used by someone who feels a bit "adventurous" today. They are there to cater for many circumstances, which include inadvertent excursions in 'g' or speed, but also include errors or uncertainties (especially the latter) in the underlying engineering. They also allow for simplification of the design cases, to a few cases with decent factors of safety, rather than many thousands of cases considering all kinds of combinations of manoeuvres and inputs. It would be a foolhardy man who took the margins in the regs and decided they were all available for use "on demand".