Florida - Carnival Corp. is shaking up its management team in an effort to rebuild its business after a deadly accident and several other mishaps drove passengers away.The cruise line operator said Monday that Howard Frank will step down as chief operating officer to take on a new role as special adviser to the CEO and chairperson. Alan Buckelew, president and CEO of Princess Cruises, will take over as chief operations officer of Carnival Corp. & PLC on Dec. 1.This follows Carnival's decision in June to name a new CEO. Board member Arnold Donald took over as head of the company, replacing Micky Arison, who had been CEO since 1979 and is the son of one of the company's co-founders.Carnival on Monday also named a new CEO for its Holland America unit and a new president of Princess Cruises. Stein Kruse, president and CEO of Holland America Line, will become CEO of Holland America Group. Jan Swartz, the company's executive vice president of sales, marketing and customer service, was promoted to president of Princess Cruises.The Miami-based company is making the leadership moves after struggling with weaker revenue since the February breakdown of the Carnival Triumph, which stranded passengers for five days in the Gulf of Mexico. That was followed by two other instances of ships having to be towed back to port. Dozens of future sailings were canceled as the company repaired those vessels.Carnival also owned the Costa Concordia, a cruise ship that hit the shore of an Italian island in 2012, capsizing and killing 32 people.The company slashed prices and invested in ship safety and services, but passengers have yet to return to its namesake cruise line at prior levels.Carnival runs cruises under 10 brands including Holland America, Princess and Cunard. The company reported in September that bookings on those lines are running in line with prior years at higher prices.Shares of Carnival added 26 cents to hit $35.10 by early afternoon, in line with the rest of the market. The company's stock is down 11% since its closing highs in February.