Page 264 - 4637

life. In addition, vehicles with low power duty cycles are subject to
corrosion during idle periods. When the equipment is not
operating, oil can drain to a static level, leaving critical surfaces
exposed to salt water condensation, thereby accelerating corrosion.
In addition, low power duty cycle gearboxes have fewer
opportunities to evaporate internal water through
frictional heating.
Although corrosion can be detected visually, a visual
inspection is, in many cases, impractical, difficult, and time
consuming. Some of the precursors and effects of aqueous
corrosion can be observed through sensing technologies and
intelligent data processing. Implementing a real-time corrosion
monitoring system for critical gearbox applications in harsh
environments would provide early warning of impending failures,
increase personnel safety, optimize maintenance or repair actions,
increase vehicle asset readiness, and improve supply chain
management.

Approach

The authors' approach to developing a comprehensive PHM
system for monitoring gearboxes for aqueous corrosion and
corrosion-induced faults builds upon merging the technologies of
oil quality monitoring, advanced corrosion modeling, and
vibration-based diagnostics. This paper describes the pertinent
aspects of the developed technology and details the application of
the corrosion monitoring system in a scaled aerospace bevel
gearbox.

Lubricant Quality

The monitoring of corrosion precursors is important in
maximizing the prognostic horizon of any component. In relation
to aqueous corrosion, water contamination in the lubricant is one

263