TM 1-1510-224-10 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. Ensure 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  710  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,  PROP  levers  should  be  in  the FEATHER position to prevent the tires from sliding. c. Warm-Up and Ground Test. Warm-up procedures   and   ground   test   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 FAT 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,  and ensure  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. e. Before Takeoff. (1) If  icing  conditions  are  expected,  activate all   anti-ice   systems   before   takeoff,   allowing   sufficient time for the equipment    to become effective. (2) If the possibility of ice accumulation on the horizontal  stabilizer  or  elevator  exists,  takeoff  shall  not be attempted. 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.  Before flight   into   icing   conditions,   set   the   pilot   and   copilot WINDSHIELD  anti-ice  switches  each  to  the   NORMAL position. g. During Flight. (1) After  takeoff  from  a  runway  covered  with snow  or  slush,  it  is  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,  periodically  exercise  trim tabs  and  controls  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   at   least   0.5   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 +50C 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. (2) Stalling  airspeeds  will  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   deicing   should   be   considered   if   moisture   was encountered   during   previous   ground   operations   or   in flight, 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° 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,  use  reverse  thrust  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  Aircraft.      When   the   aircraft   is parked   outside   on   ice   or   in   a   fluctuating   freeze-thaw temperature  condition,  use  the  following  procedures  in addition  to  the  normal  procedures  in  Section  II.    After wheel chocks are in place, release the brakes to prevent freezing. 8-29