ELECTRIC POWER ASSIST FOR IN-FLIGHT ENGINE RE-START

A hybrid electric propulsion system (100) including: a gas turbine engine (20; 120) comprising a low speed spool (30) and a high speed spool (32), the low speed spool comprising a low pressure compressor (44) and a low pressure turbine (46), and the high speed spool comprising a high pressure compressor (52) and a high pressure turbine (54); an electric motor (212A, 212B; 282) configured to augment rotational power of the high speed spool (32) or the low speed spool (30); and a controller (256) to: detect an in-flight windmill re-start condition of the gas turbine engine (20; 120); and cause power to be supplied from a power source to the electric motor (212A, 212B; 282) in order to augment rotational power of the high speed or the low speed spool during the detected in-flight windmill re-start condition.