Action
Final rule; request for comments.
Summary
We are adopting a new airworthiness directive (AD) for all Engine Alliance GP7270 and GP7277 turbofan engines. This AD requires initial and repetitive borescope inspections and removal from service before further flight if one or more burn holes are detected, in certain high-pressure turbine (HPT) stage 2 nozzles. This AD also requires mandatory removal from service of these HPT stage 2 nozzles at the next engine shop visit. This AD was prompted by a report received of inadequate cooling of the HPT stage 2 nozzle, leading to damage to the HPT stage 2 nozzle, burn-through of the turbine case, and engine shutdown. We are issuing this AD to prevent HPT stage 2 nozzle failure, leading to uncontrolled fire, engine shutdown, and damage to the airplane.