Abstract : An analysis and correlation of OH-6A helicopter engineering design values and actual operational values recorded in Southeast Asia is presented. The operational data are based on USAAMRDL Technical Report 71-60, 'Flight Loads Investigation of OH-6A Helicopters Operating in Southeast Asia.' The parameters involved include mission profiles, rotor drive system, and main and tail rotor fatigue load spectra, damage rates, and service lives. Recommendations are made for additions and changes to improve the structural design criteria for future Army observation helicopters.