Study to Improve Airframe Turbine Engine Rotor Blade Containment

An evaluation was made of energies and trajectories for a range of fan, compressor, and turbine blade fragments from high bypass ratio fan engines for typical 3 and 4 engine wide body airplanes. The weight for local armor was established. The effects of fan blade fragment impacts for areas up to 30 deg forward of the fan plane of rotation were investigated. Tests using simulated titanium blade fragments and various inlet and nacelle materials were used to determine energy absorption capabilities. The effects of fragment impact angles, size, and rotation and penetration characteristics with steel and aluminum honeycomb sheet steel multiple steel layers and Kevlar aramid fiber material containment systems were explored. Empirical and analytical armor weight determinations were verified by test. Estimates were made for the effect of added weight for airframe installed armor on fuel burned and fuel cost. In view of the adequacy of prevailing installation practices, further armor for the range of fragments considered would not appear to significantly enhance flight safety. While liberated fan blade fragments ahead of the engine do not affect the operation of remaining engines or jeopardize continued safety, they can produce undesirable secondary damage which should be considered in its own light with respect to local protection.