One of the most widely-used root cause analysis tools is the why-tree, otherwise referred to as a cause tree, root cause tree, causal factor tree, why staircase tree, cause map, etc. Many of the RCA consultants out there use some variation of this as their main investigation and analysis method. I've just posted rev 0 of an article describing the why-tree and it's usage on my root cause analysis tools page. Please have a look, and provide comments... I plan on adding some graphics later, but I want to get the text right before I do.
*Update* I've renamed the article and revised my terminology to be more generic.
Here's the article: Causal Factor Tree Analysis
by Bill Wilson