Action
Final rule; request for comments.
Summary
We are superseding airworthiness directive (AD) 2013-02-06 for all Engine Alliance (EA) GP7270 and GP7277 turbofan engines with certain part number (P/N) high-pressure turbine (HPT) stage 2 nozzle segments installed. AD 2013-02-06 required initial and repetitive borescope inspections (BSI) and removal from service of these nozzles before further flight if one or more burn holes were detected in any HPT stage 2 nozzle segment. AD 2013-02-06 also required removal from service of these HPT stage 2 nozzle segments at the next engine shop visit. This AD requires the same inspections as AD-2013-02-06, requires removal of affected HPT stage 2 nozzles at next piece-part exposure, and adds certain P/Ns to the applicability. This AD was prompted by another report of inadequate cooling of the HPT stage 1 shroud and stage 2 nozzle, leading to damage to the HPT stage 2 nozzle, burn- through of the turbine case, and in-flight shutdown. We are issuing this AD to prevent HPT stage 2 nozzle failure, uncontrolled fire, in- flight shutdown, and damage to the airplane.