Circor Aerospace is closing its Sylmar manufacturing plant as the company consolidates facilities, a move that will cost 51 jobs. The job losses are effective April 15, according to a Worker Adjustment and Retraining Notice filed with the state Employment Development Department. Among the positions to be cut are machinists, program managers, quality assurance inspectors, programmers and administrative staff. Circor manufactures landing gears and landing gear components at the plant, in addition to providing maintenance, repair and overhaul services. The Valley location had previously been privately owned Castle Precision Industries, which was acquired by Circor Aerospace in 2010. The company announced in November it expected to consolidate and take other actions over the next nine months to enhance profitability. Circor Aerospace, headquartered in Corona, is a subsidiary of Circor International, a Burlington, Mass. manufacturer for the aerospace, energy and industrial markets.