Failure Assessment Index

The Failure Assessment Index contains 4 ranking categories:

Terminology	Category
Unacceptable	1
Undesirable	2
Acceptable	3
Acceptable	4

Levels of Acceptability

For the FAI, Levels of Acceptability are assigned to each cell in the criticality matrix as shown:

Range of C_r values	Severity Category I	Severity Category II	Severity Category III	Severity Category IV
0.1 - 1.0	1	1	1	1
0.01 - 0.09	1	1	1	1
1×10⁻³ - 0.009	1	1	1	2
1×10⁻⁴ - 9×10⁻⁴	1	1	1	2
1×10⁻⁵ - 9×10⁻⁵	1	1	2	3
1×10⁻⁶ - 9×10⁻⁶	1	1	2	3
1×10⁻⁷ - 9×10⁻⁷	1	2	3	3
1×10⁻⁸ - 9×10⁻⁸	1	2	3	3
1×10⁻⁹ - 9×10⁻⁹	2	3	3	4
1×10⁻¹⁰ - 9×10⁻¹⁰	2	3	3	4