A system (166) for transferring mechanical power in a turbine engine (150/151) including a low pressure spool (162) and a high pressure spool (156) includes a power transfer unit (168) coupled between an output shaft (172) of the low pressure spool (162) and a drive shaft (174) of the high pressure spool (156) to mechanically link the low pressure spool (162) to the high pressure spool (156), and a clutch (170) coupled to the power transfer unit (168), wherein the clutch (170) is configured to transfer power produced from the low pressure spool (162) to the high pressure spool (156).