Page 31 - Root Cause Failure Analysis

22 Root Cause Failure Analysis

When did it happen?
What changed?
Who was involved?
Why did it happen?
What is the impact?
Will it happen again?
How can recurrence be prevented?

What Happened? Clarifying what actually happened is an essential requirement of
RCFA. As discussed earlier, the natural tendency is to give perceptions rather than to
carefully define the actual event. It is important to include as much detail as the facts
and available data permit.

Where Did It Happen? A clear description of the exact location of the event helps
isolate and resolve the problem. In addition to the location, determine if the event also
occurred in similar locations or systems. If similar machines or applications are elim-
inated, the event sometimes can be isolated to one, or a series of, forcing function(s)
totally unique to the location.

For example, if Pump A failed and Pumps B, C, and D in the same system did not, this
indicates that the reason for failure is probably unique to Pump A. If Pumps B, C, and
D exhibit similar symptoms, however, it is highly probable that the cause is systemic
and common to all the pumps.

When Did It Happen? Isolating the specific time that an event occurred greatly
improves the investigator’s ability to determine its source. When the actual time frame
of an event is known, it is much easier to quantify the process, operations, and other
variables that may have contributed to the event.

However, in some cases (e.g., product-quality deviations), it is difficult to accurately
fix the beginning and duration of the event. Most plant-monitoring and tracking
records do not provide the level of detail required to properly fix the time of this type
of incident. In these cases, the investigator should evaluate the operating history of the
affected process area to determine if a pattern can be found that properly fixes the
event’s time frame. This type of investigation, in most cases, will isolate the timing to
events such as the following:

Production of a specific product.
Work schedule of a specific operating team.
Changes in ambient environment.

What Changed? Equipment failures and major deviations from acceptable perfor-
mance levels do not just happen. In every case, specific variables, singly or in combi-
nation, caused the event to occur. Therefore, it is essential that any changes that
occurred in conjunction with the event be defined.