 This is a Bloomberg Money Minute. When it happened in March, it triggered a federal safety review of United Airlines. Now it has happened again. Another of United's Boeing airplanes, a 757-200, lost a main landing gear, a wheel, while taking off. Nobody was hurt. The plane took off from L.A. and landed in Denver. The tire was found in L.A. In March, a flight on its way to Japan lost a wheel but was diverted to Los Angeles.