Damage to Landfill Gas Engine-Generator

A sixteen cylinder, gas engine-generator experienced a sudden failure after operating for four years, following the replacement of a crankshaft as part of a major overhaul. One of the crankshaft counterweights had detached during operation, resulting in impact damage to the adjacent pistons, cylinder liners, connecting rods and block. Two of the three counterweight bolts had fractured due to fatigue, with the third having experienced necking due to an overload condition. Fretting experienced at the fit between the counterweight and the crankshaft indicated the fit had not been machined in a proper manner, resulting in a “high spot” at the fit. Over time, the “high spot” experienced fretting/wear, resulting in a loss in preload and subsequent fracture of the bolts liberating the counterweight.