In January 2021, I wrote a column on the shelf life of aviation piston engine oils. This brought up several comments from people wondering about the shelf life of aviation greases.
In covering this topic, I realized I had a number of tips for aircraft owners and pilots on how to make sure they are handling and using greases correctly.
First thing to know: One of the functions for grease is anti-rust protection.
Greases are based on roughly the same base oils as piston engine oils but with a thickening agent, so the main concern is a loss of the base stock or incomplete coverage of a bearing.
In a pail or tin, grease should stay usable for a significant amount of time as long as it is kept clean and has no dirt contamination. Some oil separation is OK, especially if the surface is uneven with deep grooves in it.
If you are using grease from a container every week or so, this is not a concern. But if you only use grease from the container once or twice a year, you should take a spatula and smooth the surface after each use.
Also, make sure when parts are stored with grease on them, that they are stored correctly.
A few years back we had a commercial operation that stocked extra wheel bearings for their aircraft. When they had a wheel bearing service, they would remove the bearings from the planes and install different ones from the store room. This reduced down time for the aircraft. The bearings were then cleaned and inspected and repacked.
The problem came when they then wrapped the bearings in a paper shop towel and put them back in the store room. Over time, the paper towel would wick the base oil out of the grease, leaving inadequate lubrication for the bearing when it was put back in use.
If you are going to store a packed bearing, you need to use the same oily paper that is used to wrap new bearings. Do not store them in
This post was originally published by General Aviation News on . Please visit the original post to read the complete article.