The likely operational use of the S87 aircraft during peacetime is assessed and a selection of missions are outlined by means of sortie profile codes. Using the perceived flying regime as a basis, g level exceedances spectra are derived, both vertically and laterally, arising from maneuvers, gusts and ground loads. The critical components from a fatigue viewpoint are taken to be the wing fuselage attachment lugs. The (vertical) exceedance spectrum is converted to occurrence spectra based upon the lug stresses. The occurrence spectrum are presented to a fracture mechanics program and to an S-N curve analysis. The latter method revealed an unacceptably short fatigue life well short of the aircraft's design life of 6000 hours. However, after a design change the (factored) life was satisfactory. The influence of aircraft mass on fatigue damage rates is established. A mass dependent fatigue formula, whereby damage can be readily calculated using aircraft mass(es) and the exceedance counts of discrete fatigue meter g levels, is established.


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    Title :

    S87 Close Air Support Aircraft Fatigue Analysis


    Contributors:

    Publication date :

    1988


    Size :

    276 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English




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