AD FAA-2013-0186

We are adopting a new airworthiness directive (AD) for certain General Electric Company (GE) GE90-76B, -85B, -90B, -94B, -110B1, and - 115B turbofan engines. This AD was prompted by multiple reports of distress of certain stage 1 high-pressure turbine (HPT) stator shrouds due to accelerated corrosion and oxidation, including one engine in- flight shutdown (IFSD) caused by failure of the HPT stator shrouds. This AD requires initial and repetitive on-wing 360-degree borescope inspections (BSIs) for corrosion and oxidation of stage 1 HPT stator shrouds. If a shroud is found to be distressed, this AD requires reinspection at a reduced interval or removal from service before further flight. We are issuing this AD to prevent failure of stage 1 HPT stator shrouds, resulting in an IFSD of one or more engines, loss of thrust control, and damage to the airplane.