ACHIEVING RELIABILITY AND MAINTAINABILITY GOALS WITH A COMPOSITE MAIN ROTOR BLADE

The UH-1H Composite Main Rotor Blade(CMRB) represents the current state-of-the-art in main rotor blades. To complement the new design, stringent Reliability and Maintainability (R&M) requirements were imposed. R&M were ranked one and two in priority of major design characteristics. This paper describes the intensive design support program and an extensive test/validation/demonstration effort to qualify the blade and some of the interesting results of these efforts. The program requirements of MIL-STD-785B and MIL-STD-470A were fully supported by the customer, Army Aviation System Command (AVSCOM), and Bell Helicopter Textron Inc.(BHTI) management, ensuring that most issues were addressed early and problem resolutions were incorporated into the design. The CMRB has had the most extensive test program ever pursued in the development of a main rotor blade. Fatigue tests were performed on both clean and repaired blades. A MIL-STD-471A maintainability demonstration was conducted which included 37 blade repairs of typical field incurred damage. Following the demonstration, the repaired blade underwent a 100-hour whirl test at Wright Patterson Air Force Base. Numerous other tests, such as simulated tree strikes, rain/sand erosion, and paint adhesion were also performed.