While towing a heavy load of approx. 16,000 Lbs. uphill steep grade during 100 degree temperature at low travel speed but high engine RPM a load boom came from the engine compartment. Upon inspection the fan shroud had made contact to the fan and caused severe damaged to the cooling system rendering the vehicle disabled until repairs could be made. This occurred about 30,000 miles ago however the current fan shroud has also failed under normal use. If the failed shroud damages the serpentine belt steering and breaking will be jeopardized which could lead to an accident!