DAMAGE TOLERANT DESIGN OF THE YAH-64 DRIVE SYSTEM

This paper describes the ballistic tolerance concepts that were developed and applied to the drive system design of the Hughes YAH-64 Advanced Attack Helicopter under development for the United States Army. The major design goals were defined as invulnerability and damage tolerance to the 12.7mm projectile threat, the capability for 30 minutes’ flight after ballistic damage, high reliability, and a minimum bearing fatigue life of 4500 hours. The basic design requirements for the drive system are summarized. The design philosophy, developmental problems encountered, and contributions of full-scale component tests used to attain the goals are presented. Verification of survivability design philosophy is presented including endurance testing of ballistically damaged drive system components which demonstrate a mission completion flight capability of 2 hours or greater. The result of the development work is used to assess the current state-of-the-art drive system technology.