Stochastic analysis of a system with patience time and telephonic discussion regarding nature of failure to decide type of visiting repairman

A reliability model of a two unit cold standby system is discussed wherein a regular repairman remains always with the system and may get tired while repairing a failed unit. If the regular repairman gets tired, expert repairman first discusses the nature of failure telephonically to decide whether he himself should go or to send his assistant repairman. If the assistant/regular repairman is unable to repair the failed unit, then the expert takes his own time to arrive at the system. However, on the completion of patience time or when the system becomes inoperable, the expert comes immediately to undertake the system and repairs all the units which fail during his stay at the system.