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Parametric RDA Folio

Parametric RDA Example

The data set used in this example is available in the example database installed with the Weibull++ software (called "Weibull9_Examples.rsgz9"). To access this database file, choose File > Help, click Open Examples Folder, then browse for the file in the Weibull sub-folder.

The name of the project is "Parametric RDA - Airplane AC Repair."

An analyst recorded the successive failures of the air-condition unit of an aircraft. The objective is to obtain the expected number of failures that may occur by 1,800 hours. The following data sheet shows the failure logs of the unit between 0 to 1,539 hours of observation. The observation period ended at the time of the last failure.

The LK value for the Type I model is -123.6347 while the LK value for the Type II model is -123.5964. Therefore, for this data set, the Type II model may provide the best fit (i.e., have a slightly larger LK value). The parameters of the Type II GRP model are estimated to be beta = 0.8276, lambda = 0.0389 and q = 0.2758. 

Click Calculate. The cumulative number of failures in 1,800 hours is 28.4740 or about 28 failures, and the number may be as high as about 39 failures, as shown next.

 

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