Effective Failure Rate of "n" Active Redundant Units, with "m" Required for Success (with Repair)

This tool calculates the effective failure rate of "n" active online units, where "m" are required for successful operation. The calculation implements Equation 1 shown on page 90 of the United States Air Force Rome Laboratory Reliability Engineer's Toolkit (1993). It takes into account repair of any failed units and assumes that these units are repaired within the mean corrective maintenance time (Mct) entered below. See this page for additional details on time inputs (M_ct) for system restoration. The effective mean time between failure (MTBF), sometimes referred to as the mean time between critical failure (MTBCF), is the reciprocal of the effective failure rate.

Reliability Block Diagram:

Calculation Inputs:

Number of units required for mission success (m):

Total number of active on-line units (n):

Mean corrective maintenance time (Mct), hours:

Unit failure rate (λ), failures per million hours (FPMH): Unit MTBF, hours:

Decimal places: 2 0 1 2 3 4 5 6 7 8 9 10 15 20

Featured Reference:

An Introduction to Reliability and Maintainability Engineering

Toolkit Home

Comments/Questions:


reliabilityanalytics.com

---

References:

1. United States Air Force Rome Laboratory Reliability Engineer's Toolkit (1993).
2. MIL-HDBK-338, Electronic Reliability Design Handbook.
3. Klion, Jerome, A Redundancy Notebook, Rome Air Development Center, RADC-TR-77-287, December 1987.
4. Reliability Modeling and Prediction, MIL-STD-756B, November 1981.
5. McGregor, Malcolm A., Approximation Formulas for Reliability with Repair, IEEE Transactions on Reliability, Volume R-12, Number 4, December 1963.
6. Bazovsky, Igor, Reliability Theory and Practice.

Copyright © 2010 - 2023 Reliability Analytics Corporation

Privacy Policy

All content and materials on this site are provided "as is" Reliability Analytics makes no warranty, express or implied, including the warranties of merchantability and fitness for a particular purpose; nor assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed; nor represents that its use would not infringe privately owned rights.