A gas turbine engine includes a plural spool assembly including a first spool and a second spool. The engine also includes an accessory configured to change between a motor mode and a generator mode and a transmission configured to transmit mechanical power between the accessory and at least one of the first spool and the second spool. The transmission, when the accessory is in the generator mode, is configured to transmit mechanical power from the first spool to the accessory for generating electric power at the accessory. The transmission, when the accessory is in the motor mode, is configured to transmit mechanical power from the accessory to the second spool.