When designing safety critical and software intensive embedded systems, extensive development processes have to be followed in order to ensure that the software corresponds with the software safety requirement specification. This paper describes a study performed to investigate how to use a component based approach in order to reduce the requirements of the development processes for safety critical embedded systems. Focus is on certification of individual software components by the use of integrity contracts and how this enables software component composition and re-usability, particularly between different domains. The use of our approach in system design may reduce the effort required for an assessor in certifying an entire safety critical system.