Originally Posted by
Pilot DAR
The plus 2, minus zero G limits for flaps extended are based upon the certification requirement. I'm sure that a wise aeronautical engineer back in the day realizes that there is no plausible reason to deliberately enter negative G with the flaps extended, nor be pulling more than 2G. That said, the airframe will withstand more, it is just not needed for certification.
Exactly my opinion. The standards only require +2/-0, there's no need for more than that, so nobody ever bothers to certify beyond those limits. But this only tells you what was evaluated, not how strong it really is.
G