MATERIAL FATIGUE IMPROVEMENT FOR HYBRID PROPULSION SYSTEMS

Hybrid electric propulsion systems 100 are described. The hybrid electric propulsion systems include a gas turbine engine 120 including a low speed spool 30 and a high speed spool 32, the low speed spool including a low pressure compressor 44 and a low pressure turbine 46, and the high speed spool including a high pressure compressor 52 and a high pressure turbine 56, a mechanical power transmission 150A, 150B configured to at least one of extract power from and supply power to at least one of the low speed spool 30 and the high speed spool 32, an electric motor 212A, 212B configured to augment rotational power of at least one of the low speed spool 30 and the high speed spool 32, and a controller 256 operable to control a power augmentation of at least one of the low speed spool 30 and the high speed spool 32 during an operational stress state of operation of the gas turbine engine 120.