SECTION 1.10
Design Failure Mode and Effect Analysis

Failure mode and effect analysis (FMEA) provides a methodical way to examine a design for possible ways in which failures can occur. In the FMEA, a product is examined for all the ways in which a failure may occur. For each potential failure, an estimate is made of its effect on the total system and of its seriousness. In addition, a review is made of the action being taken (or planned) to minimize the probability of failure or to minimize the effect of failure.

SECTION 1.10.1
An analysis of the design FMEA

The analysis is elaborated to include such matters as:

1. Safety. Injury is the most serious of all failure effects. In consequence, safety is handled through special programs.
2. Effect on downtime. Must the system stop until repairs are made, or can repairs be made during an off-duty time?
3. Access. What hardware items must be removed in order to get at the failed component?
4. Repair planning. This includes/ repair time, special repair tools, etc.
5. Recommendations. Suggestions for changes in designs or specifications, for added tests, for instructions to be included in manuals of inspection, operation, or maintenance.

SECTION 1.10.2
How to create a design FMEA

Due to continually changing customer needs and expectations, the importance of a disciplined technique to identify and prevent potential problems is quite great. In the design FMEA, a ranking procedure has been applied in order to assign priorities to the failure modes for further study. The ranking is twofold: (1) the probability of occurrence of the failure mode, and (2) the severity of the effect. For each of these, a scale of 1 to 10 is used. If desired, a risk-priority number can be calculated as the product of the ratings. Priority is then assigned to investigating failure modes with high risk-priority numbers.

In its most rigorous form, the design FMEA is a summary of the design engineer's thoughts, including an analysis of every item that could go wrong based on experience and past problems. This systematic approach parallels and formalizes the mental disciplines that the design engineer normally goes through in the design process for the product (reference the Design FMEA Procedure flow diagram in the appendix section).