TM 1-1510-225-10 8-26 altitudes   up   to   10,000   feet.      During   hot   weather operations,  the  principal  difficulties  encountered  are high   turbine   gas   temperatures   (ITT)   during   engine starting, overheating 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 the instrument panel and general interior for dust and sand accumulation.  Open main entrance door  and  cockpit  vent  storm  windows  to  ventilate  the aircraft. CAUTION N₁   speeds   of   70%   or   higher    may    be required  to  keep  oil  temperatures  within limits. b.    Engine Starting.  Use normal procedures in Section  II.    Engine  starting  under  conditions  of  high ambient   temperatures   may   produce   a   higher   than normal ITT during the start.  The ITT 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 (N₁).  Be prepared to  abort  the  start  before  temperature  limitations  are exceeded. c.    Before  Taxiing  and  engine  Run  Up.    Use normal  procedures  in  Section  II.    To  minimize  the possibility of damage to the engines during dusty/sandy    conditions,    activate    ice    vanes    if    the temperature is below +15 °C. 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. 8-58.  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 to avoid excessive loads on the aircraft structure. Thunderstorms  and  areas  of  severe  turbulence should be avoided.  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   that   provides adequate  maneuvering  margins  as  a  loss  or  gain  of several  thousand  feet  of  altitude  may  be  expected. The    recommended    penetration    speed    in    severe turbulence  is  170 KIAS.    Pitch  attitude  and  constant 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   the   instruments   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 lightning.  Do not use  autopilot  altitude  hold.    Maintain  constant  power settings  and  pitch  attitude  regardless  of  airspeed  or altitude indications.  Concentrate on maintaining a level attitude   by   reference   to   the   flight   director/attitude