An aircraft drive system comprising: a first engine and a second engine a main rotor gearbox (114, 214) comprising a first drive input and a second drive input; a first drive system comprising a first engine reduction gearbox connecting the first engine to the first drive input of the main rotor gearbox (114, 214) at a reduced shaft speed; a second drive system independent from and redundant with the first drive system, the second drive system comprising a second engine reduction gearbox connecting the second engine to the second drive input of the main rotor gearbox (114, 214) at the reduced shaft speed; and two or more accessory gearboxes (116, 222a, 222b) connecting an output of the first engine or the second engine with one or more accessories; wherein a first accessory gearbox (116, 222a) of the two or more accessory gearboxes (116, 222a, 222b) connecting an output of the first engine or the second engine with one or more accessories, the first accessory gearbox (116, 222a) having a non-pressurized lubrication system independent from a lubrication system associated with the main rotor gearbox (114, 214); and a second accessory gearbox (116, 222b) of the two or more accessory gearboxes (116, 222a, 222b) connecting an output of the the first engine or the second engine with one or more accessories, the second accessory gearbox (116, 222b) having a non-pressurized lubrication system independent from a lubrication system associated with the main rotor gearbox (114, 214) and from the non-pressurized lubrication system associated with the first accessory gearbox (116, 222a); wherein the second accessory gearbox (116, 222b) is independent from and redundant with the first accessory gearbox. a first engine and a second engine a main rotor gearbox (114, 214) comprising a first drive input and a second drive input; a first drive system comprising a first engine reduction gearbox connecting the first engine to the first drive input of the main rotor gearbox (114, 214) at a reduced shaft speed; a second drive system independent from and redundant with the first drive system, the second drive system comprising a second engine reduction gearbox connecting the second engine to the second drive input of the main rotor gearbox (114, 214) at the reduced shaft speed; and two or more accessory gearboxes (116, 222a, 222b) connecting an output of the first engine or the second engine with one or more accessories; wherein a first accessory gearbox (116, 222a) of the two or more accessory gearboxes (116, 222a, 222b) connecting an output of the first engine or the second engine with one or more accessories, the first accessory gearbox (116, 222a) having a non-pressurized lubrication system independent from a lubrication system associated with the main rotor gearbox (114, 214); and a second accessory gearbox (116, 222b) of the two or more accessory gearboxes (116, 222a, 222b) connecting an output of the the first engine or the second engine with one or more accessories, the second accessory gearbox (116, 222b) having a non-pressurized lubrication system independent from a lubrication system associated with the main rotor gearbox (114, 214) and from the non-pressurized lubrication system associated with the first accessory gearbox (116, 222a); wherein the second accessory gearbox (116, 222b) is independent from and redundant with the first accessory gearbox.