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Ultrasonic inspection is used to detect internal defects in rotary parts of aero engines and provide assurance of the material quality. This is carried out during manufacture at the billet and forging stages. Rolls-Royce, in collaboration with Ladish has performed a study to understand the effectiveness of these inspections and is extending the work to exploit the opportunities offered by ultrasonic phased arrays. This paper describes the study and outlines the steps within Rolls-Royces critical part inspection strategy to exploit phased arrays. In disc forgings, this direction will be dictated by a number of factors other than just the material flow from the billet to the forging. Such features as defect morphology, material anisotropy and even the solidification front of the original ingot have been found to influence final defect orientation. These are all difficult to predict in practice resulting in the need for multiple direction inspection to provide the best opportunity to detect any internal defect. The ideal inspection would therefore be to use all possible directions throughout the part volume. To achieve this within a practical inspection time is a considerable challenge which phased array technology can contribute towards as it provides the sensitivity and the ability to steer the beam. Rolls-Royce is assessing phased array capability and will use these discs to demonstrate equivalence to the current methods. With this achieved, and as part of the strategy to further improve our disc inspection process, Rolls-Royce has linked with the phased array researchers to demonstrate multidirectional inspection covering larger ranges of angles. Developing the dynamic depth focusing method, where A-scan traces are constructed from the data collected from multiple elements, will provide one method of achieving this goal. The challenge is to understand the influence of all the parameters and ensure the sensitivity is also equivalent to current capability. Once demonstrated efforts to reduce the inspection time will, no doubt also, be required.