sentences:  The addition of the rear-mounted spare tire rendered the tailgate unusable.At over US$5,000 per unit, it was relatively expensive, and by the time the Mite went into full production, the military's helicopters had become so much more powerful that the vehicle quickly became obsolete.The Marine Corps' Sikorsky H-19 with its cargo limit (including crew and fuel), for which the M422 had been developed, was being superseded by the Vietnam era UH-1 “Huey", that could carry more than 1½ times that load.