MIL-HDBK-3F Volume 3,Chapter 4 Building Block Approach for Composite Structures TABLE 4.4.1.1(b)DOD/NASA aircraft structure classification vs.PMC physical defect minimum requirements for prototypes (Reference 4.4.1.1). PART AAND B (From Figure 4.4.1.1) Aircraft Structure Physical Defect Maximum Requirements for Parts:Carbon or Glass Reinforced PMC Example Classification Description Tape Fabric PRIMARY CARRIES PRIMARY AIR LOADS s3%porosity over s10%of area. ≤5%porosity over≤10%of area. ·Fracture critical Failure will cause loss of vehicle Delaminations over s1%of area. Delaminations over s1%of area. (F/C) No edge delaminations allowed No edge delaminations allowed (including holes). (including holes). ·Noncritical(N/C) Failure will not cause loss of vehicle SECONDARY CARRIES SECONDARY AIR ≤3%porosity over≤15%of area. <5%porosity over s15%of area. OTHER LOADS Delaminations over s2%of area. Delaminations over s2%of area. Fatigue critical Failure will not cause loss of No edge delaminations allowed No edge delaminations allowed (FA/C)& vehicle but may cause cost (including holes). (including holes). economic life critical parts replacements critical(EL/C) Noncritical(N/C) Failure will not cause loss of vehicle No cost or fatigue critical parts NONSTRUCTURAL NON-OR MINOR LOAD s4%porosity over s20%of area. s4%porosity over s20%of area. BEARING Noncritical (N/C) Failure replacement of parts Delaminations over s3%of area. Delaminations over s3%of area. causing minor inconvenience. Repaired edge delaminations Repaired edge delaminations not cost critical s10%of edge length or hole <10%of edge length or hole circumference are allowed. circumference are allowed. 4-9MIL-HDBK-3F Volume 3, Chapter 4 Building Block Approach for Composite Structures 4-9 TABLE 4.4.1.1(b) DOD/NASA aircraft structure classification vs. PMC physical defect minimum requirements for prototypes (Reference 4.4.1.1). PART A AND B (From Figure 4.4.1.1) Aircraft Structure Physical Defect Maximum Requirements for Parts: Carbon or Glass Reinforced PMC Example Classification Description Tape Fabric PRIMARY CARRIES PRIMARY AIR LOADS ≤3% porosity over ≤10% of area. ≤5% porosity over ≤10% of area. • Fracture critical (F/C) • Failure will cause loss of vehicle Delaminations over ≤1% of area. No edge delaminations allowed (including holes). Delaminations over ≤1% of area. No edge delaminations allowed (including holes). • Noncritical (N/C) • Failure will not cause loss of vehicle SECONDARY CARRIES SECONDARY AIR & OTHER LOADS ≤3% porosity over ≤15% of area. Delaminations over ≤2% of area. ≤5% porosity over ≤15% of area. Delaminations over ≤2% of area. • Fatigue critical (FA/C) & economic life critical (EL/C) • Failure will not cause loss of vehicle but may cause cost critical parts replacements No edge delaminations allowed (including holes). No edge delaminations allowed (including holes). • Noncritical (N/C) • Failure will not cause loss of vehicle • No cost or fatigue critical parts NONSTRUCTURAL NON- OR MINOR LOAD BEARING ≤4% porosity over ≤20% of area. ≤4% porosity over ≤20% of area. • Noncritical (N/C) • Failure replacement of parts causing minor inconvenience, not cost critical Delaminations over ≤3% of area. Repaired edge delaminations ≤10% of edge length or hole circumference are allowed. Delaminations over ≤3% of area. Repaired edge delaminations ≤10% of edge length or hole circumference are allowed