Integrated modular avionics architectures combined with the emerging SAE TTEthernet standard provides a strong infrastructure for the deployment of mixed-critical avionic applications having stringent safety, reliability and performance requirements. The integration of such systems is a very complex and challenging engineering task. Therefore, a model-based approach, which endows system engineers with a methodology and the supporting tools to cope with this complexity, is of a paramount importance. In this research paper, we present an extension for the standard architecture and analysis modeling language AADL to enable modeling integrated multi-critical avionic applications deployed on TTEthernet-based IMA architectures. In particular, we present a metamodel which extends the core AADL metamodel with concepts and constraints relevant for this domain, we define the concrete textual syntax for this extension and we outline the implementation of this extension using the Open Source AADL Tool Environment (OSATE). Finally, we illustrate our AADL extension using a case study based on the Flight Management System.