Air Force Estimates Nearly $300 Million in Engine Rotor Cost Avoidance Published Sept. 11, 2009 By Heyward Burnett Materials & Manufacturing WRIGHT-PATTERSON AIR FORCE BASE, Ohio -- Air Force Research Laboratory's Engine Rotor Life Extension program engineers are making significant headway in reducing aircraft engine maintenance, repair, and overhaul costs. Overall, the ERLE program nets a nearly $300 million life-cycle cost avoidance for engine rotor MRO. It does so by safely extending the operational life of critical rotating turbine engine components by one additional depot interval, while also increasing depot inspection capability, reliability, and efficiency. Program emphasis is on currently fielded F-15 and F-16 fighter engines; however, ERLE technologies will benefit other legacy and future jet turbine engines, military transport aircraft engines, and commercial airline engines as well. An integral part of the Propulsion Safety and Affordable Readiness Initiative, ERLE represents a cooperative effort between development, acquisition, maintenance, and manufacturing technology stakeholders. Eventual program payoffs include increased operational life for fracture-critical turbine engine components, increased depot throughput, improved flight safety, and reduced per-component costs. ERLE's reduction of MRO expenditures could potentially free more funds for modernization activity. Life management for fracture-critical aircraft engine components is highly conservative, due in part to outdated life models and supporting nondestructive inspection technologies. Because life management practices consequently employ many worst-case assumptions, it follows that improved life prediction models--such as those incorporating more accurate stress analysis values and fracture mechanics solutions--will enhance the precision of calculating anticipated component life spans. The ERLE program has developed--and will soon implement--an ultrasonic inspection system and advanced eddy-current probe for engine disk bolt-hole inspections. These innovations, along with other important ERLE program contributions, will significantly improve the process of inspecting rotating engine parts via reductions in workload, analysis, and scan time. Full realization of ERLE program goals is largely dependent upon successful implementation of advanced life-cycle analysis and NDI as instrumental aspects of the Air Force engine life management plan.