Improvement of Inspection and Repair Procedures for GE T700-701D Power Turbine Drive Shaft Assembly Pinning Hardware

Torque indicating issues continue to plague Power Turbine Modules (PTMs) as a top reason for return. These issues can be linked to failed torque and overspeed sensors and PTM torque reference shaft issues including; sticking shafts due to torque stiction and sheared pins connecting PTM drive shafts to torque reference shafts. At the end of the PTM shaft is the pinning hardware for the torque reference shaft. In shipping and during handling of the PTM damage can occur causing the pin to shear and fail. They can fail due to inadvertent contact with the PTM or torque shaft, during shipping and handling, or after prolonged usage. Defining a reliable inspection procedure to make the determination that the PTM shaft is faulty prior to ‘on wing’ installation can save time and money for the operator. In addition, the repair procedure for sheared pin is to replace pinning hardware at Corpus Christi Army Depot (CCAD) machine shop. During the repining of the hardware the holes must be located a minimum distance from each other to preserve the integrity of PT shaft and aft insert parent metal according to the Depot Maintenance Work Requirement manual. In the presence of machine shop error, failing to maintain the minimum distance between pin holes prevents viable PT shafts from use in production. Identifying a process improvement for repair procedures of pin hardware at the machine shop can save time and money invested in overhauled PT shafts for the depot.