Happy to stand corrected
This is an interesting extract, taken from
here
A single Rolls-Royce model 250-C300/A1 (commercial designation RR300) free turbine turbo shaft engine powers the R66. The engine is mounted at a 37 degree nose-up attitude aft of the baggage compartment. A sprag type overrunning clutch or freewheel unit is splined directly into the engine power take off shaft. The free-wheel unit is connected directly to the main rotor gearbox via a shaft with flexible couplings at each end. A ring and pinion spiral bevel gear set at the main gearbox input reduces engine output speed to tail rotor driveline RPM. A second ring and pinion stage reduces speed from driveline to main rotor RPM. The main rotor gearbox is pressure lubricated with several internal oil jets.
The oil is pumped via a pump fitted to the main rotor gearbox through an airframe-mounted filter and cooled by an oil cooler, which receives its airflow from the engine cooling fan. Drive is transmitted directly to the main rotor gearbox. Engine oil cooling is via a ‘squirrel cage’ cooling fan mounted to the shaft forward of the tail rotor drive shaft, supplying cooling air through the engine oil cooler mounted on the left side of the engine bay.