Abstract: A method for repairing a turbine nozzle segment having at least one vane disposed between outer and inner bands includes separating the inner band from the nozzle segment, and joining the inner band to a newly manufactured replacement casting having an outer band and at least one vane. The replacement casting includes a mounting platform formed on one end of the vane and a boss formed on the mounting platform. A collar is joined to the inner band and has a slot formed therein. The boss is then inserted into the slot, and the mounting platform is received in a recess formed in the inner band. Joining is completed by joining the boss to the collar and the mounting platform to the inner band. The thickness of the collar is tapered in an axial direction, and a relief is formed in the collar to provide assembly clearance with adjacent components.

Abstract: There is provided a turbine airfoil having a plurality of pressure side bleed slots through which cooling air is discharged. A portion of the slot openings are covered with an outer wall which comprises a high temperature foil.

Abstract: A model-based trending process for a gas turbine engine that generates, in real-time, engine trend parameters from engine sensor data and ambient flight condition data to assess engine condition is described. The engine includes a plurality of sensors that are responsive to engine operations. The trending process is implemented using a commercially available processor coupled to the engine to monitor the engine operations, and having the desired processing speed and capacity. Engine health parameters are estimated and adjusted in a model for component diagnostics and fault detection and isolation. The trend parameters generated are retained.

Abstract: A cooling system for cooling of the squealer tip surface region of a high pressure turbine blade used in a gas turbine engine and a method for making a system for cooling of the squealer tip surface region of a high pressure turbine blade used in a gas turbine engine. The method comprises the steps of channeling apertures in a tip cap to a diameter of about 0.004″ to about 0.020″ to allow passage of cooling fluid from a cooling fluid source; applying a bond coat of about 0.0005″ to about 0.010″ in thickness to the tip cap such that the bond coat partially fills the channels; applying a porous TBC layer of at least about 0.003″ in thickness to the bond coat, such that the porous TBC fills the channels; applying a dense ceramic TBC layer over the porous layer; and, passing cooling fluid from a cooling fluid source through the channel into the porous TBC. The density of the dense TBC layer can be varied as needed to achieve desired cooling objectives.

Abstract: A chromium oxide coating is removed from a surface of an article by cleaning the article in an alkaline degreasing/rust removal solution at a degreasing/rust removal temperature of from about 180° F. to about 200° F., scale conditioning the article in an alkaline permanganate conditioning solution at a scale-conditioning temperature of from about 160° F. to about 200° F., and contacting the article to an acidic stripping solution comprising hydrochloric acid and an etching inhibitor at a stripping temperature of from about 130° F. to about 140° F.