Damage Tolerance Analysis of Dynamic Components of Rotor Wing Aircraft

The feasibility of applying the specifications of MIL-STD- 1530A to dynamic components of tilt rotor aircraft was investigated by analyzing a representative sample of components from three significant functional areas of the XV-15 aircraft. The yoke from the hub assembly, the rotating ring from the controls system and the mast from the drive system were the three components chosen. These components reflect diversity in material (excluding composites) as well as different combinations of mean and oscillatory load levels. The weight penalty estimates were made by comparing the weight of the damage tolerant configuration with that of a 10,000 hour safe-life configuration. The initial flaw sizes were 0.015 x 0.030 for surface flaws and 0.015 x 0.015 for cracks emanating from holes and corners. Of the three components analyzed, only the yoke has incurred a weight penalty. The rotating ring and mast were shown to be damage tolerant in their current design configurations.