MySQL cluster 5.6 doesn't convert invalid TIMESTAMP value to '0000-00-00 00:00:00'?
From mysql.com:


  With strict mode
  disabled, invalid dates such as '2004-04-31' are converted to
  '0000-00-00' and a warning is generated. With strict mode enabled,
  invalid dates generate an error. To permit such dates, enable
  ALLOW_INVALID_DATES.


To disable it you have 2 options.


Via SQL: execute SET @@global.sql_mode = ''; query.
Via my.cnf: change sql-mode = "STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" to sql-mode = "". Restart MySQL.