The subject matter of the invention is a line replaceable unit (LRU) (2) for an aircraft (1). According to the invention, the LRU has: a) a first main memory (7) which contains the software required for certification of the LRU (2), b) a second main memory (8), which is separate from the first main memory (7) and in which a user of the LRU can store individual software which does not adversely affect the certification basis of the LRU. The subject matter of the invention is, furthermore, an arrangement comprising an LRU according to the invention and a database (12) with appropriate individual software, as well as a corresponding method for operation of an LRU.