Manufacturing sales posted a small gain in September, boosted by the aerospace industry, even as the Canadian economy faced increased headwinds. Statistics Canada said Thursday manufacturing sales rose 0.4 per cent in September to $49.8 billion, ahead of economists’ expectations of a gain of 0.3 per cent. “The gain reflected higher production in the aerospace product and parts industry and increased sales of primary metals,” the agency said. However, excluding the aerospace sector, which climbed 43 per cent to $1.8 billion, total manufacturing sales slipped 0.7 per cent due to declines in the motor vehicle assembly industry. The overall gain…