TM 55-1510-219-10 shall  be  made  with  brake  deice  on  and  with  the  ice vanes   extended   to   preclude   the   possibility   of   ice build-up on engine air inlets. Monitor oil temperatures     to     insure     operation     within     limits. Before   flight   into   icing   conditions,   the   pilot   and copilot  WSHLD  ANTI-ICE  switches  should  be  set  at NORMAL position. g. During Flight. (1) After  takeoff  from  a  runway  covered with  snow  or  slush,  it  may  be  advisable  to  leave brake deice ON to dislodge ice accumulated from the spray   of   slush   or   water.      Monitor   BRAKE   DEICE annunciator    for    automatic    termination    of    system operation   and   then   turn   the   switch   OFF.      During flight, trim tabs and controls should also be exercised periodically to prevent freezing.  Insure that anti-icing systems are activated before entering icing conditions.  Do not activate the surface deice system until ice has accumulated one-half to one inch.  The propeller   deice   system   operates   effectively   as   an anti-ice system and it may be operated continuously in   flight.      If   propeller   imbalance   due   to   ice   does occur, it may be relieved by increasing RPM briefly, then returning to desired setting. Ice   vanes   must   be   extended   when operating  in  visible  moisture  or  when  freedom  from visible  moisture  cannot  be  assured,  at  5°C  FAT  or less.  Ice vanes are designed as an anti-ice system, not a deice system.  After the engine air inlet screens are  blocked,  lowering  the  ice  vanes  will  not  rectify the condition.  Ice vanes should be retracted at 15°C FAT    and    above    to    assure    adequate    engine    oil cooling. (2) Stalling  airspeeds  should  be  expected to increase when ice has accumulated on the aircraft causing  distortion  of  the  wing  airfoil.    For  the  same reason,  stall  warning  devices  are  not  accurate  and should   not   be   relied   upon.      Keep   a   comfortable margin  of  airspeed  above  the  normal  stall  airspeed. Maintain  a  minimum  of  140  knots  during  sustained icing    conditions    to    prevent    ice    accumulation    on unprotected  surfaces  of  the  wing.    In  the  event  of windshield   icing,   reduce   airspeed   to   226   knots   or below. h. Descent.  Use normal procedures in Section II.  Brake icing should be considered if moisture was encountered   during   previous   ground   operations   or inflight in icing conditions with gear extended. i. Landing.    Landing  on  an  icy  runway  should be  attempted  only  when  absolutely  necessary  and should not be attempted unless the wind is within 10 degrees  of  runway  heading.    Application  of  brakes without skidding the tires on ice is very difficult, due to  the  sensitive  brakes.    In  order  not  to  impair  pilot visibility,  reverse  thrust  should  be  used  with  caution when   landing   on   a   runway   covered   with   snow   or standing   water.      Use   procedures   in   Section   II   for normal landing. j. Engine  Shutdown.    Use  normal  procedures in Section II. k. Before    Leaving    the    Aircraft.        When    the aircraft  is  parked  outside  on  ice  or  in  a  fluctuating freeze-thaw    temperature    condition    the    following procedures   should   be   followed   in   addition   to   the normal procedures in Section II.  After wheel chocks are in place, release the brakes to prevent freezing. Fill fuel tanks to minimize condensation, remove any accumulation  of  dirt  and  ice  from  the  landing  gear shock  struts,  and  install  protective  covers  to  guard against possible collection of snow and ice. 8-55.  DESERT OPERATION AND HOT WEATHER OPERATION. Dust, sand, and high temperatures encountered   during   desert   operation   can   sharply reduce   the   operational   life   of   the   aircraft   and   its equipment.  The abrasive qualities of dust and sand upon turbine blades and moving parts of the aircraft and  the  destructive  effect  of  heat  upon  the  aircraft instruments  will  necessitate  hours  of  maintenance  if basic   preventive   measures   are   not   followed.      In flight, the hazards of dust and sand will be difficult to escape,   since   dust   clouds   over   a   desert   may   be found   at   altitudes   up   to   10,000   feet.      During   hot weather operations, the principle difficulties encountered    are    high    turbine    gas    temperatures (TGT) during engine starting, over-heating of brakes, and longer takeoff and landing rolls due to the higher density  altitudes.    In  areas  where  high  humidity  is encountered, electrical equipment (such as communication  equipment  and  instruments)  will  be subject    to    malfunction    by    corrosion,    fungi    and moisture absorption by nonmetallic materials. a. Preparation For Flight.  Check the position of the   aircraft   in   relation   to   other   aircraft.      Propeller sand    blast    can    damage    closely    parked    aircraft. Check that the landing gear shock struts are free of dust and sand.  Check instrument panel and general interior for dust and sand accumulation.  Open main entrance   door   and   cockpit   vent   storm   windows   to ventilate the aircraft. 8-24