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Reliability Growth Tracking

This tool provides the ability to plot and track reliability growth trends based on a series of failure times entered into box 2, one per line. It implements the AMSAA reliability growth model and statistical tests for trends, as published in MIL-HDBK-189 (Ref. 1). For several examples, skip inputs 1 - 4 and select one of the test sets (last input under item #5, Options).

Calculation Inputs:

1. Total accumulated test time (unit-hours):

2. Failure times, one per line:

If multiple systems are tested, failure times are in units of cumulative unit-hours at each failure point. For example, two units are tested, unit 1 fails at 80 hours while unit 2 has accumulated 50 hours, the failure time is 130 unit-hours.
Example failure times

3. Significance levels:

a) For "no growth" test of hypothesis:
b) For Cramer-von Mises goodness of fit test:

4. Confidence level

5. Options:

Chart based on data fitted to AMSAA model
Chart based on calculated instantaneous value at each failure point
Calculate reliability at test time (unit-hours):

Decimal places: Apply to all.
Send results to:

Use a test data set (ignores inputs above):

Featured Reference:

Reliability, Maintainability and Risk: Practical Methods for Engineers
Reliability, Maintainability and Risk: Practical Methods for Engineers

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Reliability Analytics Corporation


  1. MIL-HDBK-189 Base, Reliability Growth Management (13 Feb 1981).
  2. MIL-HDBK-189C, Reliability Growth Management (14 Jun 2011).
  3. MIL-HDBK-781, Reliability Test Methods, Plans, and Environments for Engineering Development, Qualification, and Production (14 Jul 1987).
  4. RADC-TR-84-20, Reliability Growth Testing Effectiveness.
  5. Pecht, Michael (Editor) Product Reliability, Maintainability, and Supportability Handbook.
  6. Smith, David J. Reliability, Maintainability and Risk: Practical Methods for Engineers.