Risk Priority Number (RPN)

Risk Priority Number (RPN) is calculated for every active failure path within the system model.

The RPN of any Functional Failure Mode is the multiplication of Occurrence (O), Severity (S) and Difficulty of Detection (D) values as follows:

• Occurrence (O): Occurrence of the first event in the Functional Failure Mode failure path
• Severity (S): Severity of the End-Effect
• Difficulty of Detection (D): Minimum detectability within the failure path to that End-Effect.

Notes:

• If a Functional Failure Mode has multiple possible paths to the same end-effect, MADE will take the minimum D of all the paths to the end-effect.
• If a Functional Failure Mode has multiple paths to different end-effects, RPN will be calculated for each path, and each RPN uses the minimum 'D' value of a failure path leading to an end-effect.
• Risk Priority Number (RPN) can be reported in a FMECA report automatically generated by MADE as shown below.