R&M requirements allocation in upgrading a system

The article deals with a method of R&M requirements allocation which is applicable in upgrading technical systems. The method is based on the presumption that the basic R&M parameters of main sub-systems of original design are available and the requirement for the availability level of the upgraded system is stated. The main aim of the method is a requirements allocation which ensures an increase in system availability to a required level with minimal design changes. The basis of the method is a mathematical model describing dependencies between the overall system availability and availability of separate sub-systems. The model allows testing a system-availability response to changes of sub-systems availability. By using the model, a procedure was devised for specifying the sub-system (or sub-systems) which is the most suitable for upgrading. At the same time, the procedure allows allocation of R&M requirements for this optimal sub-system (or sub-systems) so that overall system-availability will meet the stated requirements. The method was developed and used during the upgrading of a heavy tracked vehicle