Vehicle is upfitted as a school bus. Forward fuel tank strap failed in operation. Our company operates more than 100 of these vehicles and we experience a failure of fuel tank straps at a rate of about one vehicle per month. If the 2nd strap would also fail the gasoline tank would become dislodged and present a re hazard. This is even more critical as these vehicles are carrying students as a school bus. We perform visual inspections of the straps at 6 month intervals (per Pennsylvania these vehicles are subject to Semi-Annual State Inspection). There were no symptoms of the problem before this failure. There are never symptoms of the problem.