The PLF1A-2 was the first high bypass (6:1 bypass ratio) fan engine run in North America. Lycoming's high bypass fan engine concept evolved from a 1950s series of conceptual studies directed to better compete with turboprops. By 1962, prototype design had begun utilizing the Lycoming T55-L-7 turboshaft as the engine core. Considerable feasibility tests were conducted in both private and government facilities in 1964 and 1965, and a window of opportunity opened with the early-1970s Air Force AX competition.
Derived from the PLF1A, Lycoming's YF102-LD-100 engine for the Northrop A-9 close combat aircraft performed very well during aircraft testing, although the Fairchild A-10 was selected in the fly-off competition. Lycoming later redirected efforts toward the commercial market with the ALF502D version of the YF102, which was successfully applied to the Canadair Challenger CL600 executive jet and British Aerospace BAe 146 commercial jetliner.
This PLF1A-2 was one of two prototype development engines, but never flew.