LONG TERM STORAGE EFFECTS ON DISC CUTTERS

THE EGRESS PROGRAM WILL IMPOSE A REQUIREMENT ON DISC CUTTERS WHICH HAS NOT BEEN ADDRESSED IN COMMERCIAL WORK. THE EGRESS CUTTERS MUST WITHSTAND LONG TERM STORAGE IN AN UNDERGROUND ENVIRONMENT, AND THEN FUNCTION RELIABLY. IN COMMERCIAL WORK A RULE OF THUMB IS TO REPLACE OR REBUILD CUTTERS IF STORAGE EXCEED FOR (4) MONTHS. THEREFORE, NO DATA EXISTS ON THE EFFECTS OF LONG TERM BEARING DEFORMATION, LUBRICANT DEGRADATION, SEAL ELASTOMER DETERIORATION, COMPONENT CORROSION OR OTHER AGING PHENOMENON WHICH COULD CAUSE MISSION FAILURE. THE PHASE I EFFORT PROPOSED WILL IDENTIFY AND ADDRESS ALL THE STORAGE ISSUES IN A TYPICAL CUTTER CONFIGURATION. IN ADDITION, A METHODOLOGY FOR ANALYZING FAILURE MODES WILL BE DEVELOPED. FINALLY, THE FEASIBILITY OF SPECIFIC DESIGN CHANGES DIRECTED AT THE LIMITED PERFORMANCE REQUIREMENTS OF A CUTTER, AFTER LONG TERM STORAGE, WILL BE INVESTIGATED. PHASE II EFFORTS WOULD INCLUDE THE MANUFACTURE OF SPECIALIZED CUTTERS, ACCELERATED LIFE TESTS, AND PROOF OF PERFORMANCE TESTS. THE ANALYSIS METHODOLOGY DEVELOPED IN PHASE I WILL BE APPLIED TO ASSESS WHETHER A CUTTER CAN BE DEVELOPED TO SERVICE BOTH STORAGE AND PERFORMANCE REQUIREMENTS, OR IF PERIODIC MAINTENANCE OR REPLACEMENT IS NECESSARY.