The fundamental usefulness of the additional gas turbine propulsion was also demonstrated .
The fundamental usefulness of the additional gas turbine propulsion was also led to the introduction of the DB Class 210 ( with a more powerful turbine : an AVCO Lycoming T53 - L 13 ) .
The fundamental usefulness of the additional gas turbine propulsion was also demonstrated and led to the introduction of the DB Class 210 ( with a more powerful turbine : an AVCO Lycoming T53 - L 13 ) .