poldek77 agreed, see my post #7. It's airworthiness not flight operations for the 2.1%.
EASA CS 25.121 Climb: one-engine inoperative
(d) Approach. In a configuration corresponding to the normal all-engines operating procedure [...]
(1) The steady gradient of climb may not be less than 2·1 % for two-engined aeroplanes [...], with
- (i) The critical engine inoperative, the remaining engines at the go-around power or thrust setting;
- (ii) The maximum landing weight;
- (iii) A climb speed established in connection with normal landing procedures, [...] and
- (iv) Landing gear retracted.
You make me go research things!
Oh well then,
another file on the drive.