(aviation, of a turbine engine) To increase in rotational speed, producing an increase in thrust. / (figuratively) To be brought into full operation; to reach full potential or capacity.

Third-person singular simple present indicative form of spool down

Third-person singular simple present indicative form of spool up

present participle of spool down

present participle of spool up

(aviation, of a turbine engine) To decrease in rotational speed, producing a decrease in thrust.