TM 1-1510-225-10 8A-24 a.  Preparation  for  Flight.    Accumulations   of snow,  ice,  or  frost  on  aircraft  surfaces  will  adversely affect  takeoff  distance,  climb  performance,  and  stall speed  to  a  dangerous  degree.    Such  accumulations must  be  removed  before  flight.    In  addition  to  the normal  exterior  checks,  following  the  removal  of  ice, snow, or frost, inspect wing and empennage surfaces to verify that these surfaces remain sufficiently cleared. Also, move all control surfaces to confirm full freedom of movement.  Assure that tires are not frozen to wheel chocks or to the ground.  Use ground heaters, anti-ice solution, or brake deice to free frozen tires.  When heat is applied to release tires, the temperature should not exceed  71  °C  (160 F).    Refer  to  Chapter  2  for  anti- icing, deicing, and defrosting treatment. b.  Engine Starting.  When  starting  engines  on ramps  covered  with  ice,  propeller  levers  should  be  in the FEATHER position to prevent the tires from sliding. To  prevent  exceeding  torque  limits  when  advancing condition   levers   to   HIGH  IDLE   during   the   starting procedure,  place  the  power  lever  in  BETA  and  the propeller  lever  in  HIGH  RPM  before  advancing  the condition lever to HIGH IDLE. c.  Before Taxi and Engine Runup. Procedures    are    the    same    as    those    outlined    in Section II. d.  Taxiing.  Whenever possible, taxiing in deep snow,   light-weight   dry   snow,   or   slush   should   be avoided,  particularly  in  colder  OAT  conditions.   If  it  is necessary to taxi through snow or slush, do not set the parking brake when stopped.  If possible, do not park the aircraft in snow or slush deep enough to reach the brake  assemblies.    Chocks  or  sandbags  should  be used  to  prevent  the  aircraft  from  rolling  while  parked. Before   attempting   to   taxi,   activate   the   brake   deice system, insuring that the bleed air valves are open and that the condition levers are in HIGH IDLE.  An outside observer   should   visually   check   wheel   rotation   to ensure   brake   assemblies   have   been   deiced.      The condition  levers  may  be  returned  to  LOW  IDLE  as soon as the brakes are free of ice. If the possibility of ice accumulation on the horizontal  stabilizer  or  elevator  exists,  do not attempt takeoff. e.  Before   Takeoff.      If   icing   conditions   are expected,  activate  all  anti-ice  systems  before  takeoff, allowing  sufficient  time  for  the  equipment  to  become effective. NOTE Following  takeoff  from  runways  covered with  snow  or  slush,  consideration  should be   given   to   operating   the   landing   gear through   several   complete   cycles   (within limits)  to  dislodge  ice  accumulated  from the spray of slush and water and to prevent gear freezing in the retracted position. f.   Takeoff.        Takeoff    procedures    for    cold weather operations are the same as for normal takeoff. Taking off with temperature at or below freezing, with water, slush, or snow on the runway, can cause ice to accumulate on the landing gear and can throw ice into the  wheel  well  areas.    Such  takeoffs  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  temperature  to  ensure  operation within  limits.    Before  flight  into  icing  conditions,  the pilot's and copilot's 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 ON 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.  Ensure that anti-icing systems are activated before  entering  icing  conditions.    Do  not  activate  the surface deice system until ice has accumulated to 1/2 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. (2)   Ice    vanes    must    be    extended    when operating  in  visible  moisture  or  when  freedom  from visible moisture  cannot  be  assured,  at  +5  °C  OAT  or less.    Ice  vanes  are  designed  as  an  anti-ice  system, not a deice system.  After the engine air inlet screens are blocked, extending the ice vanes will not rectify the condition.    Ice  vanes  should  be  retracted  at  +15  °C OAT and above to assure adequate engine oil cooling. (3)   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 WARNING