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The role of composites in commercial aircraft

The recent discovery of the wreckage and flight recorder from Air France 447 at the bottom of the Atlantic ocean, and the inspection of 79 Southwest Airlines planes after a foot hole tore open in a fuselage, warrants a review of the role of composites in the civilian airline industry.

To manufacture composites, strong materials such as carbon fibers are embedded in a stable epoxy resin. The sheet can then be wrapped, creating a fuselage that is light and strong.  However research continues on how to categorize the properties and lifespan of such materials.  

A composite material's failure commences internally and at a microscopic level.  During initial delamination, fibers separate slowly from the resin.  Once a critical load is reached, the separate proceeds catastrophically and results in the immediate destruction of the material. 

In contradistinction, one can see metal cracking and anticipate its failure.  While the inspection of the Southwest planes pinpointed manufacturing defects, all such metal failures are generally visible with the eye long before they approach failure.

Consider the crash of American Airlines 587 in 2001.  It took off too soon and entered into the turbulent wake of another large plane.  One cause of the crash was overuse of the rudder to counter wake turbulence.  This overuse stressed the rudder and it snapped off.  In that light, one might wonder about the turbulent thunderstorms over the Atlantic the night Air France 447 crashed. Both of these planes were made from composites.  All lives were lost aboard the Air France jet. No one died from the manufacturing defects in the Southwest planes.

Some have called for a cessation of the use of composites; but this is an over-reaction.  These materials function well, result in tremendous cost savings and efficiencies and enable our way of life.   However, we should engage in scientific discussion and research on how to ensure the long-term stability of such materials and an understanding of their durability.