Abstract: On October 14, 2003, an employee was operating a Mayco, Model PF-30, Serial Number 900110, plaster pump for plastering work for the construction of a new restaurant. A blockage somewhere in the plaster pumping system caused the pressure to increase in the line until the surge hose adaptor was explosively separated from the Part D coupler that secured the surge hose to the plaster pump's output pipe. This pump was capable of generating pressures of 750 to 1,000 lbs per square inch of pressure at the pump manifold and output pipe. The plaster pump's pressure relief safety valve had not been routinely serviced according to the manufacturer's operating manual and it did not function properly to safely release the increased system pressure. The employee was standing at the pump next to the output pipe trying to locate the line blockage when the hose suddenly came free and struck him in the lower left leg just above the ankle resulting in a compound fracture. The employee was hospitalized at Desert Valley Hospital.