New generation aircraft structures need to be lighter in order to allow for more sophisticated avionics and weapons systems.. The increased use of lightweight, thermoset composite materials has partially addressed this dilemma. However, thermoset composites possess certain undesirable characteristics, including brittleness and a variety of manufacturing, storage, and processing limitations. On the other hand, new fiber reinforced thermoplastic (FRTP) composite materials offer many of the advantages of advanced thermoset composites, including reduced weight and higher fatigue life. However, unlike thermosets, they possess high toughness, unlimited shelf life, and can be reprocessed and spliced/combined together to reduce scrap. To explore these materials, an evaluation program was performed at McDonnell Douglas Helicopter Company with the objective of replacing an existing, primary, metallic structure on the AH-64 Apache helicopter with an FRTP structure.