Which of the following is an example of a failure mode according to FMECA?

The identification of a failure mode in FMECA (Failure Mode, Effects, and Criticality Analysis) pertains to the specific manner in which a failure occurs that can affect the performance or functionality of a system. In this context, "corroding" is a clear example of a failure mode because it describes a specific degradation mechanism that can lead to failure in a component or system.

Corrosion typically results from a chemical reaction that compromises the material, leading to increased wear, fatigue, or eventual failure if not addressed. This directly ties into reliability engineering as understanding this failure mode enables technicians and engineers to develop strategies for maintenance, prevention, and intervention, thereby enhancing the overall reliability of the asset.

The other options do not represent failure modes since they describe outcomes or improvements rather than the nature of failure itself. Increased productivity and enhanced performance are positive outcomes reflecting improvement in operations, while unplanned maintenance is more of a consequence of a failure rather than the failure mode itself. Thus, "corroding" aligns perfectly with the definition of a failure mode in the context of FMECA, making it the correct choice.