United Technologies Corporation

Christopher Mark Palazzini

Michael A Weisse

William D Owen

Daniel J Whitesell

Eric W Malmborg

Robert W Baumgarten

Douglas A Senecal

Frank E Palko

Hollow fan blades for turbo fan gas turbine engines are formed of two separate detail halves. Each detail half has a plurality of cavities and ribs machined out to reduce weight. The floor and opposite interior walls of each cavity are machined simultaneously. The configuration minimizes the number of cutter plunge cuts for the internal cavities, and maximizes cutter size, in order to minimize the time required to machine them. These detail halves are subsequently bonded and given an airfoil shape in the forming operation.

Method for making a hollow fan blade with machined internal cavities

A hollow fan blade for turbo fan gas turbine engines is formed of two separate detail halves. Each detail half has a plurality of cavities and ribs machined out to reduce weight. These detail halves are subsequently bonded and given an airfoil shape in the forming operation. The present invention provides a hollow fan blade with internal cavity and rib geometry with improved durability that permits the bonding and forming to be performed without the need for gas pressurization. The ability to form the hollow fan blade of the present invention without gas pressurization is a result of the cavity and rib geometry and the orientation of the ribs. The ribs are tapered and transition into a compound radius of the floor that simulates the classical arch design element. The orientation of the ribs is generally in a parallel plane with the load vector that results from forming loads during the pre-form and final form operations. This orientation provides compressive stress transfer into the ribs and away from the concave and convex skins. The rib spacing is controlled where ribs can not be held in a parallel plane with the load vector.

Hollow fan blade for gas turbine engine

Hollow fan blades for turbo fan gas turbine engines are formed of two separate detail halves. Each detail half has a plurality of cavities and ribs machined out to reduce weight. These detail halves are subsequently bonded and given an airfoil shape in the forming operation. In one embodiment, contiguous cavities are formed around freestanding ends of the ribs to reduce the number of cavities required. The freestanding end of each rib is flared such that it has a larger width than the rest of the rib. The cavity extends continuously around the free, flared end of the rib.

A method for repairing an airfoil is provided that includes the steps of: (a) determining repair regions of the airfoil that are likely to be damaged during a period of operation; (b) creating a stress profile for the airfoil that considers dynamic, steady-state, and residual stresses; (c) selecting a replacement section patch line using the stress profile and the determination of those regions likely to be damaged during operation; (d) providing an airfoil replacement section with a predetermined shape having a bond surface that substantially mates with the patch line; (e) removing a portion of the airfoil up to the patch line; (f) bonding the airfoil replacement section to the airfoil along the patch line; and (g) shaping the patched airfoil.

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Windsor, CT, United States of America

Christopher Mark Palazzini