Failure analysis of cooling fan gearbox

This article describes the findings of an investigation on the failure of a cooling fan gearbox. The failure analysis was aimed at identifying the root cause of the gear damage in order to prevent their reoccurrence. Detailed investigation using several characterisation techniques such as visual and metallographic examinations, hardness testing, and different chemical analyses showed that the gears failed by contact fatigue accelerated by alternating high loads. The failure contributing factors are discussed and identified. Practical corrective actions were suggested in order to avoid similar failures.