In the field of AI ethics, after the introduction of ethical frameworks and the evaluation thereof, we seem to have arrived at a third wave in which the operationalisation of ethics is central. Operationalisation is required, since ethics frameworks are often not suited to be used by data scientists in the development of AI-based services or products. Therefore, in this paper, we aim to contribute to this third wave by mapping AI ethical principles onto the lifecycle of an AI-based digital service or product and combining it with an explicit governance model to clarify responsibilities in operationalisation. We then discuss practical, conceptual, and political implications of this analysis to end with key challenges around operationalising AI ethics.