sentences:  AFGROW's history traces back to a crack growth life prediction program (ASDGRO) which was written in BASIC for IBM-PCs by E. Davidson at ASD/ENSF in the early-mid-1980s.In 1985, ASDGRO was used as the basis for crack growth analysis for the Sikorsky H-53 helicopter under contract to Warner-Robins ALC.The program was modified to utilize very large load spectra, approximate stress intensity solutions for cracks in arbitrary stress fields, and use a tabular crack growth rate relationship based on the Walker equation on a point-by-point basis (Harter T-Method).