Had hydraulic fuses been fitted to the DC-10 and the 747 the accident in Iowa might not have happened or, possibly not have been so bad. It would also have saved the 747 in Japan that suffereed the loss of all three hydraulic systems due to failure of the pressure bulk head. In that incident the vertical fin was blown off but that in itself is survivable.
I don't know if fuses were even considered in the design of both aircraft but based on my experience if it were recommended by the reliability engineer the safety engineer would counter the reliability engineer by saying that they had not concieved of any failure that would cause loss of all three systems. On the other hand if they were considered, the management would offer the same argument used by the safety engineers and would add that it would add weight and cost. General electric proved through the use of Boolean Algebra that the fan disc had a projected probability of failure of 1 10-9 or greater. It is not known if the reliability engineer had consiered a faulty manufacturing process as a mode of failure. It was later proved that there was sand entrapped in the fan disc as a result of a faulty manufacturing process. Since GE stated in their safety analysis that the probility of failure was so low then Douglas never felt it was necessary to protect the elements of the hydraulic systems in the vicinity of No. 2 engine. A similar failure caused the loss of a 737 in Manchester and the failure resulted because the engine manufacturer (P&W) said the engine would never fail in the manner that it did and no precautions were taken by Boeing to protect the underwing. Think Concorde!
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The Cat
[This message has been edited by Lu Zuckerman (edited 05 January 2001).]