Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain General Electric Company (GE) Model CF34-1A, CF34-3A, CF34- 3A1, CF34-3A2, and CF34-3B engines. This proposed AD was prompted by a dual engine power loss event and consequent manufacturer investigation, which revealed corrosion in the high-pressure compressor (HPC) case affecting the variable geometry (VG) system. This proposed AD would require performing certain restart tests and, depending on the results of the tests, additional actions. This proposed AD would also require performing a borescope inspection (BSI) of the HPC case for corrosion and, depending on the results, a VG system functional check for pressure evaluation. This proposed AD would also require, depending on inspection results, performing a force gage test on the feedback cable for tightness and a visual inspection of the VG system for obstruction and, if necessary, removal of the engine from service. This proposed AD would also require revising the airworthiness limitations section (ALS) of the existing engine maintenance manual to incorporate the VG system functional check. The FAA is proposing this AD to address the unsafe condition on these products.