Examination of a failed Class 50 radiator fan blade (TM-MET-49)

For several years Class 50 radiator fans supplied by Airscrew Howden have been subject to fracture in service and/or premature scrapping as a result of fatigue cracking of the blades. Examination of early fractures indicated that fatigue initiation was occurring from dross inclusions lying in the mid-blade leading and trailing...