A wash system for a gas turbine engine comprising a compressor section, a turbine section, and an accessory gearbox, the wash system comprising: a core turning assembly comprising a motor configured to be mechanically coupled to the gas turbine engine for rotating one or more components of the compressor section or the turbine section at a rotational speed greater than two revolutions per minute and less than five hundred revolutions per minute during washing operations of the gas turbine engine; and a wash fluid line configured to be fluidly connected to a location within at least one of the compressor section or the turbine section of the gas turbine engine, the wash fluid line configured to provide a wash fluid to at least one of the compressor section or the turbine section during rotation of at least one of the compressor section or the turbine section by the motor, characterised in that the motor is configured to be mechanically coupled to the accessory gearbox, wherein the accessory gearbox of the gas turbine engine comprises a plurality of accessory gears; wherein the accessory gearbox further comprises a plurality of accessory pads positioned adjacent to the respective plurality of accessory gears, and is configured to be attached to an outer casing of the gas turbine engine; wherein the core turning assembly further comprises an offset tool and an adapter, the offset tool coupled to the motor and the adapter, the adapter being coupled to a selected one of the plurality of accessory pads, other than a starter pad, wherein the adapter is also coupled to a selected one of the plurality of accessory gears of the accessory gearbox other than a starter gear of the accessory gearbox, wherein the adapter includes a shaft extending through a cylindrical opening of the accessory gear configured to couple to a splined portion of the accessory gear, wherein the accessory gear rotates the components of the gas turbine engine by transferring a torque from the motor, through the offset tool and adapter to the accessory gear, to the starter gear, to a driveshaft of the accessory gearbox, and to and through a transfer gearbox to the component of the gas turbine engine, at least in part via the plurality of accessory pads. a core turning assembly comprising a motor configured to be mechanically coupled to the gas turbine engine for rotating one or more components of the compressor section or the turbine section at a rotational speed greater than two revolutions per minute and less than five hundred revolutions per minute during washing operations of the gas turbine engine; and a wash fluid line configured to be fluidly connected to a location within at least one of the compressor section or the turbine section of the gas turbine engine, the wash fluid line configured to provide a wash fluid to at least one of the compressor section or the turbine section during rotation of at least one of the compressor section or the turbine section by the motor, characterised in that the motor is configured to be mechanically coupled to the accessory gearbox, wherein the accessory gearbox of the gas turbine engine comprises a plurality of accessory gears; wherein the accessory gearbox further comprises a plurality of accessory pads positioned adjacent to the respective plurality of accessory gears, and is configured to be attached to an outer casing of the gas turbine engine; wherein the core turning assembly further comprises an offset tool and an adapter, the offset tool coupled to the motor and the adapter, the adapter being coupled to a selected one of the plurality of accessory pads, other than a starter pad, wherein the adapter is also coupled to a selected one of the plurality of accessory gears of the accessory gearbox other than a starter gear of the accessory gearbox, wherein the adapter includes a shaft extending through a cylindrical opening of the accessory gear configured to couple to a splined portion of the accessory gear, wherein the accessory gear rotates the components of the gas turbine engine by transferring a torque from the motor, through the offset tool and adapter to the accessory gear, to the starter gear, to a driveshaft of the accessory gearbox, and to and through a transfer gearbox to the component of the gas turbine engine, at least in part via the plurality of accessory pads.