Pratt & Whitney will potentially provide all the engines for all 100 of the Airbus A320neo aircraft to be ordered by International Lease Finance.
While the ILFC agreement - yet to be firmed - covers the selection of the PW1100G geared turbofan for 60 aircraft, P&W says it also includes engine options for another 40.
The geared-turbofan powerplant is running against the rival CFM International Leap-X engine for the aircraft.
Given that the ILFC deal includes 75 A320neo and 25 A321neo twinjets, the PW1100G could eventually be fitted to both types.
The geared turbofan is designed to increase operating efficiency by enabling the turbine and fan to operate at separate, optimum speeds.
ILFC's aircraft are scheduled for delivery from 2016, says P&W, the year Airbus is planning to introduce the A320neo.
Virgin America, IndiGo and TAM have all agreed to take the re-engined twinjet but none has yet selected an engine.
P&W says the leasing company's agreement is a "strong endorsement" of the geared turbofan.
ILFC chief Henri Courpron says the engine technology will "improve fuel efficiency and address other environmental advantages for our customers".
ILFC also reinforced its single-aisle aircraft portfolio by firming an order for 33 Boeing 737-800s, which are exclusively powered by CFM International's CFM56 engine.