TM  1-1520-240-10            8-4-3 8-4-17.  Before Leaving Helicopter. If  the  helicopter  is  to  be  parked  outside  for  extended periods, maintenance personnel should install all protec- tive covers and secure the rotor blades. When ambient temperatures of –18_C and below are expected and the helicopter is to be parked outside, maintenance person- nel should also remove the battery and store it in a warm area until required for further operation. 8-4-18.  Desert and Hot Weather Operation. Refer to FM 1-202, Environmental Flight. 8-4-19.  General. The reduction in power available and the resulting de- crease in helicopter performance caused by reduced air density and EAPS is the main consideration during des- ert and hot weather operation. Therefore, greater em- phasis must be placed on determining performance dur- ing mission planning. 8-4-20.  Preparation for Flight. A normal preflight inspection is to be conducted as de- scribed in section II. Extra emphasis should be placed on equipment which may be affected by higher tempera- tures, such as tires, seals and hydraulic components. In addition, check equipment for signs of deterioration or excessive abrasion from blowing dust or sand. Windows and doors should be opened to provide increased ven- tilation. 8-4-21.  Engine Starting. The normal engine starting procedures in section II are to be used. 8-4-22.  Taxiing. Braking should be kept to a minimum to prevent overhea- ting. Ground operation in general should be kept to a minimum. 8-4-23.  Takeoff, Climb, Cruise, and Descent. Helicopter performance may be reduced; therefore tech- niques should be adjusted accordingly. 8-4-24.  Landing. The  landing  procedures  in  Section  II  apply.  Braking should be kept to a minimum to prevent overheating. 8-4-25.  Engine Shutdown. It may be necessary to motor the engines if temperature does not decrease below 350_C. It may not be possible to lower the temperature to 260_C. If the temperature will not decrease below 260_C, terminate motoring when the temperature indication stabilizes. NOTE Pilots should make an attempt to avoid motor- ing periods in excess of 15 seconds. 8-4-26.  Before Leaving the Aircraft. Leave all windows and doors open to increase ventila- tion, except during conditions of blowing dust or sand. 8-4-27.  Turbulence and Thunderstorm Operation. 8-4-28.  Prior to Entering Turbulent Air. CAUTION To prevent engine overtorque, do not enter forecast moderate or stronger turbulence with the thrust brake (portion of the CCDA) inoperative or BARO ALT engaged. Prior to entering moderate or stronger turbulent air, the following should be accomplished: 1.   BARO ALT switch — Disengaged. 2.   Crew — Alert. 3.   Airspeed — Adjust as follows:. a.   In  severe  turbulence,  decrease  air- speed  to  Vne  minus  15  knots  or  to maximum range, whichever is slower. (Refer to Chapter 7.) b.   In moderate turbulence, decrease air speed to Vne minus 10 knots or to maxi mum range, whichever is slower. (Refer to chapter 7.) 4.   Longitudinal cyclic trim — Select MAN, then adjust both actuators for the airspeed to be flown.  This  is  accomplished  to  prevent  the cyclic trim actuators from cycling. 5.   Loose equipment — Secure. 6.   Safety   belts   and   shoulder   harneses   — Tighten. 8-4-29.  In Turbulent Air. The  thrust  control  position,  when  adjusted  for  the  air- speeds mentioned above, should be maintained and the attitude indicator should be used as the primary pitch instrument. The altimeter and vertical velocity indicator may vary excessively in turbulence and should not be relied upon. Airspeed may vary as much as 40 knots. By maintaining a constant thrust control position and a level flight attitude on the attitude indicator, airspeed will re- main relatively constant even when erroneous readings are presented by the airspeed indicator.