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Composites, specifically fibre-reinforced polymers, are increasingly utilised in aerospace industry particularly as they are lightweight, and possess respectable mechanical properties capable of sustaining environmental constraints. Automated Fibre Placement (AFP) has emerged as a manufacturing solution in the composites industry over the past few years. It has improved the production process, and delivers better quality parts. Mechanical tests show that the adhesion quality between plies is strongly depending on the manufacturing process (placement speed, consolidation). The aim of this work is to give an ultrasonic non-destructive evaluation (NDE) method of the adhesion quality in such structure.In this study, the sample under investigation is a representative plate of an AFP-manufactured part provided by Safran. It consists of 8-plies carbon fibre-reinforced Low-Melt Polyaryl-ether-ketone (LM-PAEK) composite, with a total thickness of 1.47 mm, resulting in an average ply thickness of approximately 183 µm. To evaluate the integrity of the ply interfaces, a high-frequency non-destructive ultrasonic method is employed using the Scanning Acoustic Microscope (SAM) PVA TEPLA 301 in pulse-echo method. A numerical model based on the Debye Series Method (DSM), developed by J.M Conoir and implemented by P. Marechal is used. It expresses the reflection and transmission coefficients at each interface and, recursively, calculates the global reflection and transmission coefficient. The latter enables signal reconstruction resulting in echoes associated with each layer of the structure. Interphase conditions can be fed to the model in order to simulate its nature and the potential defects. Optimisation methods were used in order to estimate the interphase properties and, consequently, the adhesion quality of the composite.