Page 7-42 Engine Shutdown
After extended periods of ground engine operation above 1600 RPM or when the CHT indicator shows values within the upper half of the green arc, reduce engine power to between 600 and 800 RPM for a period of not less than 2 to 3 minutes prior to engine shutdown. This procedure is intended to reduce internal turbocharger temperatures and preclude the possibility of premature accumulation of carbon on the turbine shaft seals.