A range of turboshaft powerplants have been used to power the numerous variants of the AW109, from the original Allison 250-C14 engines to the Turbomeca Arriel 1K1 and Pratt & Whitney Canada PW206 of more modern aircraft. Powerplants can be replaced or swapped for during airframe overhauls, resulting in increasing lifting capacity and other performance changes. In the case of single-engine failure, the AW109 is intended to have a generous power reserve even on a single engine. The engines drive a fully articulated four-blade rotor system. Over time, more advanced rotor blade designs have been progressively adopted for the AW109's main and tail rotors, such as composite materials being used to replace bonded metal, these improvements have typically been made with the aim of reducing operating costs and noise signature. According to Rotor&Wing, the type is well regarded for its "high, hot, and heavy" performance.