Effective Failure Rate of Two Active Redundant Units, with Different Failure and Repair Rates

This tool calculates the effective failure rate of two active on-line units, where "1 of 2" units are required for success. Each unit may have a different failure and/or repair rate. The calculation implements Equation 2 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 unit mean corrective maintenance time (Mct) entered below. See this page for additional details on time inputs (M_ct) for system restoration.

Reliability Block Diagram:

Calculation Inputs:

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

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

Unit A mean corrective maintenance time (Mct_A), hours:

Unit B mean corrective maintenance time (Mct_B), hours:

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

Featured Reference:

Reliability Theory and Practice

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.

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.