Reuters: United Technologies Corp. faces a long road to win approval for its $23 billion plan to buy avionics maker Rockwell Collins Inc., and the biggest bumps could be in Brussels rather than Washington. Opponents of the deal could argue the combination gives the aircraft parts supply company undue market power. An early sign of trouble came when Boeing Co. said it intended to take a “hard look” at the proposed deal. “Until we receive more details, we are skeptical that it would be in the best interest of — or add value to — our customers and industry,” Boeing said in a statement.