Hi squibb,
What I was attempting to explain was that the mass value ('t') is the visible limit (painted on the deck); the dynamic loads due to impact on touchdown (weights) used during the design process are: the normal touchdown at 1.5 x the mass ('t') - which equates to a ROD of 6ft/sec; and the emergency touchdown at 2.5 x the mass ('t') - which equates to a ROD of 12ft/sec. These are then conditioned by the other factors.
Geoff is absolutely correct in his comments on my interpretation of the safety studies (which are only used if approval is sought to accept a helicopter above the original design MCTOM).
Jim