TM 55-1510-222-10 abrasive  characteristics  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   many   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   distances   due   to   the   higher   density   altitudes encountered.          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. reparation For Flight.  Check the position of the aircraft in relation to other aircraft.  Propeller blown sand can  damage  nearby  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. b. Engine   Starting.      Use   normal   procedures   in Section   II.      Engine   starting   under   conditions   of   high ambient    temperatures    may    produce    a    higher    than normal   TGT   during   the   start.      The   TGT   should   be closely monitored when the condition lever is moved to the LOW IDLE position.  If overtemperature tendencies are encountered, the condition lever should be moved to IDLE  CUTOFF  position  periodically  during  acceleration of  gas  generator  RPM  (NI).    Be  prepared  to  abort  the start before temperature limitations are exceeded. c. Warm-Up Ground Tests. Use normal procedures in Section II. d. Taxiing.    Use  normal  procedures  in  Section  II. When   practical,   avoid   taxiing   over   sandy   terrain   to minimize   propeller   damage   and   engine   deterioration that   results   from   impingement   of   sand   and   gravel. During   hot   weather   operation,   use   minimum   braking action to prevent brake overheating. e. Takeoff.    Use  normal  procedures  in  Section  II. Avoid  taking  off  in  the  wake  of  another  aircraft  if  the runway surface is sandy or dusty. f    During    Flight.        Use    normal    procedures    in Section II. g. Descent.  Use normal procedures in Section II. h. Landing.  Use normal procedures in Section II. i. Engine  Shutdown.    Use  normal  procedures  in Section II. CAUTION During  hot  weather,  if  fuel  tanks  are completely filled, fuel expansion may cause   overflow,   thereby   creating   a fire hazard. j. Before Leaving Aircraft.  Use normal procedures in Section II.  Take extreme care to prevent sand or dust from  entering  the  fuel  and  oil  system  during  servicing. During   hot   weather,   release   the   brakes   immediately after   installing   wheel   chocks   to   prevent   brake   disc warpage. 8-54 TURBULENCE AND THUNDERSTORM OPERATION. CAUTION Due  to  the  comparatively  light  wing loading, control in severe turbulence and  thunderstorms  is  critical.   Since turbulence  imposes  heavy  loads  on the aircraft structure, make all necessary changes in aircraft attitude   with   the   least   amount   of control  pressures  possible  to  avoid excessive loads on the aircraft structure. Thunderstorms  and  areas  of  severe  turbulence  should be    avoided.        However,    if    such    areas    are    to    be penetrated, it will be necessary to counter rapid changes in attitude and accept major indicated altitude variations. Penetration   should   be   at   an   altitude   which   provides adequate   maneuvering   margins   as   a   loss   or   gain   of several thousand feet of altitude may be expected.  The recommended speed for penetration of severe turbulence  is  150  KIAS.    Constant  pitch  attitude  and power   settings   are   vital   to   proper   flight   technique. Establish  recommended  penetration  speed  and  proper attitude  prior  to  entering  turbulent  air  to  minimize  most difficulties. False indications by the pressure instruments due to barometric pressure variations within the  storm  make  them  unreliable.    Maintaining  a  pre- established    attitude    will    result    in    a    fairly    constant airspeed.  Turn cockpit and cabin lights on to minimize the  blinding  effects  of  lighting.    Do  not  use  autopilot altitude hold.  Maintain 8-24