As each program within CU*BASE that creates a maintenance record has its own rules for how to display dates, the CUFMAINT table may contain two date layouts within the MNTDAT (Maintenance Date) column. Instead of that column, we suggest using the MNLSTUPDDT (Activity Date) column for your needs. 

For further explanation, 
MNTDAT (Maintenance Date) is the numeric version and will vary in layout between YYMMDD and MMDDYY occasionally; usually when the same data point can be updated by multiple programs. As stated above, each program has its own rules for writing to CUFMAINT.

MNLSTUPDDT (Acitivty Date) is the ISO date version and will be consistently YYYY-MM-DD. For example, row 1 and row 2 of this screenshot have the differing layouts, each of which also have a standardized “Activity Date” equivalent.