Airworthiness Directives; Rolls-Royce, plc RB211 Trent 700 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD) that is applicable to Rolls-Royce, plc RB211 Trent 700 series turbofan engines. This action requires repositioning of the oil metering jet up into the oil distributor within the bevel gearshaft, followed by repetitive inspections of the Magnetic Chip Detector (MCD). Evidence of driving bevel gearshaft ball bearing failure requires replacement of the Step Aside Gearbox (SAGB). This amendment is prompted by reports of uncommanded engine rundowns caused by failure of the SAGB driving bevel gearshaft ball bearing due to oil starvation. This causes a loss of drive to the external gearbox and accessories, resulting in an inflight engine shutdown. The actions specified in this AD are intended to prevent inflight engine shutdowns caused by SAGB driving bevel gearshaft ball bearing failure.