Boeing 737-528, G-GFFE
During ground operation, the cast inflow turbine of the APU suffered a radially contained failure. This resulted in vanes separating from the casting as its two liberated halves came into rapid contact with the containment structure. The hot vane debris was ejected through the jet pipe and spread across the rear of the stand and the width of the adjacent taxiway. The failure was one of nine broadly similar events to the type of turbine wheel, each attributed to a casting defect. Efforts have been made to improve the manufacturing process, without proven success, and no reliable method has been found to detect the defect in new or existing turbines. No method of establishing a safe in-service life has been determined for this component but the hazard to airport staff remains very low.
Boeing 737-528, G-GFFE 01-07.pdf (340.22 kb)