This application relates to a method of repairing a cracked blade outer air seal for a gas turbine engine.
Gas turbine engines are known, and include a plurality of sections. Generally, a compressor section receives air, compresses the air and delivers that air into a combustion section. In the combustion section the compressed air is mixed with fuel and combusted. The products of this combustion pass downstream over a turbine section that generally includes a plurality of rotors each having removable blades. During engine operation, the blades are subjected to the product of combustion and are designed to efficiently utilize the energy in the products of combustion to rotate the turbine rotors. The turbine section also includes a stationary blade outer air seal (“BOAS”) that sits radially outwardly of the rotating turbine blades to form a tight seal between the outer periphery of the blade and the inner periphery of the blade outer air seal. In this manner, the products of combustion are guided over the turbine blades, rather than avoiding the turbine blades.
Because blades outer air seals are subject to high temperatures from the products of combustion, they are provided with intricate structures, such as cooling air passages. However, the blades outer air seals are still subjected to stresses and can crack. These blade outer air seals generally have not been repaired. Instead, damaged blade outer air seals have been replaced with undamaged blade outer air seals. This is somewhat undesirable, as undamaged blade outer air seals are often relatively expensive due to their complex structure.
It is known to repair gas turbine engine components, such as turbine blades and blade outer air seals, by utilizing laser powder fusion techniques. In these techniques, laser powder fusion machines deliver liquefied powder metal at locations in need of repair, such as cracked locations
In a method according to the present invention, a blade outer air seal is repaired, with a weld repair being utilized on a crack, wherein the weld repair includes laser powder fusion techniques, and wherein a clean weld pass is then made on the crack without any additional deposition of powder metal.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
As shown in
The repaired blade outer air seal may then be heat treated in step 70. A restored surface may be returned back toward a desired final shape by blending or grinding in step 72 and the blade outer air seal may then be reinstalled in step 74 for return to service.
With the example embodiment, blade outer air seals are easily and reliably repaired such that they will have a longer useful life than in the prior art.
Although embodiments have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.