Multifunction secondary power system starting method

摘要

A multifunction secondary power system (10) for use aboard an aircraft or other vehicle provides the functions both of an auxiliary power unit and of an emergency power unit. The power system (10) includes two turbine engines (12, 22) operable under differing conditions, a gearbox (34) receiving power from the two engines (12, 22) selectively through overrunning clutches (74,84), and a plurality of accessory devices (36, 38, 40) receiving shaft power from either of the two engines (12, 22) through the gearbox (34). The gear box (34) includes a third clutch (64) operably interposed between the clutches (74, 84) which selectively delivers shaft power from the engine (22) to the engine (12) to affect the start thereof.