Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_16505 ( "Team" text, "Outgoing manager" text, "Manner of departure" text, "Date of vacancy" text, "Replaced by" text, "Date of appointment" text, "Position" text )

### Question ###
When is the date of vacancy of Davy Fitzgerald being a replacement?

### Accurate SQL ###

SELECT "Date of vacancy" FROM table_16505 WHERE "Replaced by" = 'Davy FitzGerald'