* TSX falls 141.09 points, or 1.01 percent, to 13,791.88 * Eight of the 10 main index sectors decline * RBC has biggest negative influence on market By John Tilak TORONTO, Jan 24 (Reuters) - Canada's main stock index recorded its biggest single-day drop in more than six weeks on Friday as expectations that the U.S. Federal Reserve will scale back its stimulus program heightened and weighed heavily on emerging-market assets. The fears about the Fed, combined with soft economic data from China, pushed down the prices of some commodities, including oil and copper. In turn, the resource-sensitive Toronto Stock Exchange benchmark index fell for a second straight session and looked set to end the week lower. It also hit a one-week low. "It's clearly not positive for Canada because some emerging markets account for a lot of the commodity purchases," said Lorne Steinberg, president of Lorne Steinberg Wealth Management. "One senses the air coming out of the balloon as investors focus on risk," he added. "Sentiment can turn quickly, and that alone can have a self-fulfilling prophecy when it comes to markets." The benchmark S&P/TSX composite index was down 141.09 points, or 1.01 percent, at 13,791.88. Eight of the 10 main sectors on the index were in the red. Financials, the index's most heavily weighted sector, gave back 1.2 percent. Royal Bank of Canada shed 1.4 percent to C$70.41 and had the biggest negative influence on the market. Bank of Nova Scotia lost 1.1 percent to C$63.53. Shares of energy producers dropped 1.2 percent, with Suncor Energy Inc slipping 1.1 percent to C$37.38. The materials sector, which includes mining stocks, fell 1.2 percent. Potash Corp was down 2.5 percent at C$35.64, and Teck Resources Ltd stumbled 2.4 percent to C$26.49.