Maneuver-To-Maneuver Load Cycle Case Study

In traditional fatigue evaluation methodologies, Ground-Air-Ground (GAG) cycles account for a significant portion of accumulated fatigue damage for many components. GAG cycles are typically conservative and thought to cover Maneuver- To-Maneuver (MTM) and Rotor-Start-and-Stop (RSS) cycles. Proper development and fielding of Condition Based Maintenance (CBM) systems require refined fatigue methodologies to appropriately account for MTM damage. This paper proposes use of damage based on the rainflow count of sequenced load pairs with CBM in place of adapting traditional GAG methodologies. The sequenced load pair method is illustrated using simplified data and demonstrated on more realistic notional flight test data. Use of sequenced load pairs is recommended for signals with significant low-frequency content.