My reading of the specified weights (which are only options under CS-23) are that they are used to prevent designers using overly light individuals to acheive unrealistic figures.
Isn't the minimum seat weight requirement a hangover from the days (BCAR-S issue 1) when microlights had to show that they wouldn't go outside W&B limits at the four points of
- Max cockpit weight; full fuel
- Max cockpit weight; no fuel
- Min cockpit weight; full fuel
- Min cockpit weight; no fuel
I wonder if that's where the hard-edged maximum seat weight requirement grew from too.
Genghis seems to know about these things, perhaps he'll clarify.
MadamB