With the A400M a military transport aircraft is being developed and certified according to both civil and military rules and regulations. As can be expected, some of the civil and military requirements and rules contradict to each other. This paper will give an overview of how the four independent MIL-STD-1553B military data buses installed on A400M were certified to civil standard for entry into service of the aircraft aimed for the end of 2012. This paper describes some of the issues encountered and how they were solved and also highlights the impact of stringent civil lightning strike requirements and how they can be met by the 1553 standard. On the A400M, the aircraft level certification of the 1553 data buses is under the responsibility of CASSIDIAN, subsidiary of EADS.