Article: Requirements Development, Verification, and Validation Exhibited in Fam

Question

Article: Requirements Development, Verification, and Validation Exhibited in Famous Failures by A. Terry Bahill1, * and Steven J. Henderson1,

Do you agree with the authors' judgement given below on why the GE rotary failed system failed?

RD= yes

VER= no

VAL=yes

In 1986, General Electric Co. (GE) engineers said they could reduce the part count for their new refrigerator by one-third by replacing the reciprocating compressor with a rotary compressor.

Furthermore, they said they could make it easier to machine, and thereby cut manufacturing costs, if they used powdered-metal instead of steel and cast iron for two parts. However, powdered-metal parts had failed in their air condition- FAMOUS FAILURES 5 ers a decade earlier [Chapman, Bahill, and Wymore, 1992: 19]

Six hundred compressors were “life tested” by running them continuously for 2 months under temperatures and pressures that were supposed to simulate 5 years’ actual use. Not a single compressor failed, which was the good news that was passed up the management ladder.

However, the technicians testing the compressors noticed that many of the motor windings were discolored from heat, bearing surfaces appeared worn, and the sealed lubricating oil seemed to be breaking down. This bad news was not passed up the management ladder!

By the end of 1986, GE had produced over 1 million of the new compressors. Everyone was ecstatic with the new refrigerators. However, in July of 1987 the first refrigerator failed; quickly thereafter came an avalanche of failures. The engineers could not fix the problem. In December of 1987, GE started buying foreign compressors for the refrigerators. Finally, in the summer of 1988 the engineers made their report. The two powdered-metal parts were wearing excessively, increasing friction, burning up the oil, and causing the compressors to fail.

GE management decided to redesign the compressor without the powdered-metal parts. In 1989, they voluntarily replaced over 1 million defective compressors. The designers who specified the powdered-metal parts made a mistake, but everyone makes mistakes.

Systems Engineering is supposed to expose such problems early in the design cycle or at least in the testing phase. This was a verification failure.

Explanation / Answer

Apparently, during the testing phase of the compressor, defects and problems were beginning to show- discoloration, wear, and leakage of lubricating oil. Also, the period of test was only 2 months, and their 2 month performance was to predict their life of 5 years- which is very risky. These defects might not have affected the performance of the compressors during such a short period of time, however in the long run, they can be detrimental and lead to the full breakdown of the compressor, as found out later. The quality and testing department failed to report this, somehow, to the management.

So I agree with the authors conclusion that GE Systems Engineering failed to verify these problems, leading to the failure of the compressors.

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