142 High Performance Thermoplastic Resins and Their Composites thermoset using a bismaleimide resin exhibits improved high temperature performance and improved toughness and resistance to delamination.Although F/A-18s will continue to be produced with carbon/epoxy outer wing panels,these experimental panels will permit comparison between thermoplastic and thermoset composites behavior under flight conditions.The reprocessability feature of thermoplastic composites has been demonstrated in this project.In the first part that was made,a disbond was present because of inadequate pressure.The part was put back into the heated press and reprocessed with correct pressure which fused the disbonded area. Development is focused at the design and construction of fully automatic manufacturing equipment capable of producing thermoplastic composite structures and will include an on-line non-destructive inspection capability. 7.2.4 Landing Gear Strut Door and Access Panel [254] The Northrop Corporation initiated and completed a project to design,fabricate and test two carbon/PEEK landing gear strut doors and access panels for the F-5F aircraft [254]. These two non-primary structures were selected because of the complexity of the design for the strut door and to acquire durability data for the access panel.This latter component is a damage prone part since it is often removed during aircraft servicing. The inner and outer skins of the landing gear door were fabricated with the thermoplastc composite materlal IM6/PEEK.Sixteen and forty-nine ply lay-ups were required for the inner skin and outer skin,respectively.The inner skin was molded using a pressure forming diaphragm process and the outer skin was formed with a vacuum bag autoclave process.The weight savings for the thermoplastic inner and outer skins compared to aluminum skins were 31%and 33%respectively.Assembly was accomplished with skin-to- skin adhesive bonding.The thermoplastic door assembly has carried the proof-test loads. The original access panel made from magnesium alloy has been fabricated with a 10 ply AS4/PEEK laminate formed in a hot platen press.Both the landing gear door and access panel have been demonstrated as flight worthy by Northrop Corporation and will be flight tested. Components for a developmental access door made of woven carbon fabric/PPS laminate sheets have been thermoformed in one-step for Boeing.Seven thermoplastic composite components were ultrasonically welded to assemble the 55.9 cm hollow access door. The thermoplastic composite door exhibited ten times the fracture toughness of carbon/epoxy 2521.142 High Performance Thermoplastic Resins and Their Composites thexmoset using a bismaleimide resin exhibits improved high temperature performance and improved toughness and resistance to delamination. Although F/A- 18s will continue to be produced with carbon/epoxy outer wing panels, these experimental panels will permit comparison between thermoplastic and thermoset composites behavior under flight conditions. The reprocessability feature of thermoplastic composites has been demonstrated in this project. In the first part that was made, a disbond was present because of inadequate pressure. The part was put back Into the heated press and reprocessed with correct pressure which fused the disbanded area. Development is focused at the design and construction of fully automatic manufacturing equipment capable of producing thermoplastic composite structures and will include an on-line non-destructive inspection capability. 7.2.4 Landing Gear Strut Door and Access Panel [254] The Northrop Corporation initiated and completed a project to design, fabricate and test two carbon/PEEK landing gear strut doors and access panels for the F-5F aircraft [254]. These two non-primary structures were selected because of the complexity of the design for the strut door and to acquire durability data for the access panel. This latter component is a damage prone part since it is often removed during aircraft sewicing. The inner and outer skins of the landing gear door weie fabricated with the thermoplastic composite material IM6/PEEK. Sixteen and forty-nine ply lay-ups were required for the inner skin and outer skin, respectively. The inner skin was molded using a pressure forming diaphragm process and the outer skin was formed with a vacuum bag autoclave process. The weight savings for the thermoplastic inner and outer skins compared to aluminum skins were 3 1% and 33% respectively. Assembly was accomplished with skin-to￾skin adhesive bonding. The thermoplastic door assembly has carried the proof-test loads. The original access panel made from magnesium alloy has been fabricated with a 10 ply AS4/PEEK laminate formed in a hot platen press. Both the landing gear door and access panel have been demonstrated as flight worthy by Northrop Corporation and will be flight tested. Components for a developmental access door made of woven carbon fabric/ PPS laminate sheets have been thermoformed in one-step for Boeing. Seven thermoplastic composite components were ultrasonically welded to assemble the 55.9 cm hollow access door. The thermoplastic composite door exhibited ten times the fracture toughness of carbon/epoxy [252]