Using OAF Personalizations, i need to set a default value to a field, depending on another field val

I am working in the Maintenance Super User responsibility, and i need the field ACTIVITY CAUSE, had a default value according with the WORK ORDER TYPE.

If work order type = "CORRECTIVE" then ACTIVITY CAUSE should have the "FAILURE" value.

I haven't found the way to do it, by OAF Personalizations.

Any ideas?