The EC145 features a larger cabin space than the older BK 117 C1 helicopter with internal space increased by 46 cm (18 in) in length and 13 cm (5 in) in width, increasing cabin volume by to . Other improvements over the BK 117 include an increased maximum take-off weight and greater range, achieved partially by the adoption of composite rotor blades, which were derived from the smaller EC135. The EC145 has a hingeless rotor system with a monolithic titanium hub; the helicopter was originally powered by a pair of Turboméca Arriel 1E2 turboshaft engines, later aircraft are powered by the upgraded Turboméca Arriel 2E engine. A key feature of the rotorcraft is the variable rotorspeed and torque matching system (VARTOMS), derived from the BK 117, which Eurocopter has attributed as making the EC145 "the quietest helicopter in its class".