Читать книгу System Reliability Theory - Marvin Rausand - Страница 141

A flashlight is part of the safety equipment in a plant. During an emergency, the flashlight is switched on, but does not give any light. A proximate (or direct) cause is that the battery is dead. If we have access to the flashlight and the battery after the emergency is over, it is straightforward to verify whether or not this was the true proximate cause.

Any battery will sooner or later go dead and if the flashlight is an essential safety equipment, it is part of the maintenance duties to test and, if necessary, replace batteries at regular intervals. “The battery has not been tested/replaced at prescribed intervals” is therefore a cause of the proximate cause. By asking “why?” this happened several times, we may get to the root cause of the failure.

For the purpose of this book, we define a root cause as: