Certification of the Composite Outer Wing of the ATR72

Abstract

The ATR72 was the first civil aircraft with a composite wing, to be certified JAR/FAR 25 (Joint Aviation Requirements/Federal Aviation Regulations). Using the latest developments composites ACJ 25603, AC20-107A comply with the requirements of JAR/FAR 25; the ATR72 composite outer wing box was certified by the DGAC in September 1989 and by FAA in December 1989. This paper deals with Aerospatiale's innovative approach, focusing on four major certification topics: the determination of allowables from statistical analysis substantiated by tests on cross-ply plain and notched laminates; the fatigue and damage tolerance substantiations performed by analysis to show the non-initiation of fatigue damage and by full-scale test for the no-growth of acceptable manufacturing defects and accidental damages; the development of a probabilistic approach to determine the inspection intervals for accidental impacts in damage-tolerance justifications; the compliance philosophy developed to qualify a second source material (approved by the company in 1992).

Damage development in woven carbon fibre thermoplastic laminates with PPS and PEEK matrices: A comparative study

“…Thus, PEEK matrix being much tougher than PPS in tension, possesses fracture toughness 4-8 times greater than that of PPS, as was reported by Vielle et al 1 referring to Tropis et al 15 Three laminates with three stacking sequences were produced in Ten Cate Advanced Composites (TCAC) for different types of tests with each matrix: where N is the number of fabric layers; t the thickness of sample and m f the mass of an unit square of a fabric. The average values and standard deviations of thickness and FVF of the laminates are shown in Table 2.…”

Validation and modeling of aeronautical composite structures subjected to combined loadings: The VERTEX project. Part 1: Experimental setup, FE-DIC instrumentation and procedures

“…The choice of size is driven by the following compromise: the specimen must be large enough to represent the structural problems and to limit the Saint-Venant's effects while being small enough to keep costs within reasonable limits. In [36], the size of the area of interest was 200 200 mm 2 , which was too small. In the other machines described, the size of the test pieces was of the order of one square meter, which is necessary to represent fuselage sections but is too large and too expensive for a technological test piece.…”

“…The upper levels of the pyramid involve structural tests on more specific specimens that are more representative of the designs, but always under uniaxial loading. In addition, for composite structures, sizing and damage tolerance methods were developed as part of the certification of the first composite primary structure certified on a civil aircraft, the ATR 72 wing box (Tropis et al [2]) and must also be validated by the pyramid of tests. However, these methods, although they have the advantage of being robust, have the disadvantage of being extremely costly (tens of thousands of tests per aircraft) and generating very long design cycles.…”

Discrete Impact Modeling of Inter- and Intra-laminar Failure in Composites

“…In the field of aeronautics, it has been demonstrated that a permanent indentation between 0.25 and 0.5 mm is detectable during detailed visual inspection with a probability greater than 99% [12].…”

“…the dent depth of the impact point, is a crucial aspect for the certification of composite structures with damage tolerance concepts [10][11][12]. Indeed the size of such an indentation determines whether impact damage can be detected or not.…”