FAA Urged to Investigate GE CF6-6 Engine Component Safety

The Federal Aviation Administration is being urged to conduct a directed safety investigation (DSI) of the general electric cf6-6 turbine engine to establish a cyclic threshold at which the fan forward shaft and the fan disks should be separated and inspected for defects in the components. The DSI should include a review and analysis of certification, testing, and stress analysis data used to establish life limits and inspection frequencies for these components, manufacturing processes associated with the production of the fan assembly and fan forward shaft, metallurgical analysis of the front flange of the fan forward shaft where cracks were recently discovered, maintenance practices involved in the assembly and disassembly of the fan disks and fan forward shaft for potential damage during these processes, nondestructive inspection of spare fan disks and fan forward shafts beginning with those components with the highest number of cycles in service, and nondestructive inspections of fan disks on installed engines that may be performed by an approved inspection procedure. This directive was superseded by A-90-088.