EE WAS TIGHTENING BOLT ON REAR AXLE OF MACK WATER TRUCK, USING A 3/4"" AIR WRENCH IN RIGHT HAND AND A 1 5/16"" BOXED-END WRENCH IN LEFT HAND. WHILE HOLDING THE AIR WRENCH WITH ELBOW IN AN AWKWAR D POSITIOHN IN RIGHT HAND THE RIGHT ELBOW POPPED. A CHIP FROM ELBOW BONE LODGE IN JOINT. A CAST WAS APPLIED TO RIGHT ARM, ELBOW AREA.