I posted a similar question to yours a while back on this forum. The answer comes from JAR 25.1001 Subpart A/ FAR 25.1001 Subart E:
(in my own words)
"Fuel Jettison must be installed unless it is shown that an aircraft meets the Approach/Landing Climb requirements at MTOW less the weight of fuel required for a 15 minute flight (comprised of a TOFF, approach, and landing at the airport of departure)".
Adjusting the approach/landing flap setting within 110% of the Vs1g for "all-engines" approach/landing setting is possible to meet the 2.1% gradient (2 eng acft- 1 inop) or 2.7% (for 4 eng acft- 1 inop) in approach config or 3.2% in landing config (all engines).
HJ