Nprd 2011

[leifesk]

My company doesn't have a copy of NPRD 2011 but our reliability prediction software includes it and the components listed have MANY similar failure rates. Upon contacting the software company, they claim accuracy referencing NPRD 2011.

Question is, does NPRD 2011 really have identical failure rates for many dissimilar components?

Anti-Collision Light, General/Arm, Motor/Battery, General/Windshield Panel, General……

[dnicholls]

Failure rates within the RIAC NPRD-2011 databook are based on the number of cumulative operating hours for a given component and the number of failures of that component that are experienced during those cumulative operating hours. These failure rates are not a function of component type. A motor that experiences 5 failures in 2.5 million operating hours will have the same failure rate as a computer hard drive that experiences 5 failures in 2.5 million operating hours (or some approximate multiple that results in an identical/similar failure rate). Also, two dissimilar components, each of which experiences 0 failures in 200,000 operating hours will have the same lower-bound failure rate.

I hope that this information is helpful to you.

[leifesk]

Thank you for your response.

I understand what you said, and considering a similar platform (environment), it makes sense. My uncertainty results in that the fact that components fail at different rates. My underlying suspension is that the software company has made reference errors with regard to NPRD 2011. These errors result in dissimilar components with the same failure rate (to 6th decimal places) for 8 items in that component type.

Actuator - Boost
Anti-Collision Light - General
Adapter - Air
Adhesive - General
Air Cleaner - Intake
Accessory Drive Assembly - General
Accelerometer - Lateral
Windshield Panel - General

Would you be able to email me an excerpt from NPRD for any two of the listed components for reference?

[dnicholls]

Within NPRD-2011, I looked at the "Actuator, Boost", "Anti-Collision Light - General" and "Adhesive - General" failure rates. All have a failure rate of < 4.289581 based on the summation of 9 individual data records from the same source each having 0 failures and each having identical totals for both the individual (and therefore summarized) cumulative number of operating hours. Since these records all came from the same data source, and none had failures, the failure rate results are what would be expected. Therefore, it appears that your software is working correctly.