TM 1-1510-223-10 When  the  aircraft  is  being  towed,  a  qualified person  must  be  in  the  pilot's  seat  to  maintain control by use of the brakes.  When towing, do not  exceed  nose  gear  turn  limits  (fig.  2-42). Avoid short radius turns, and always keep the inside    or    pivot    wheel    turning    during    the operation.      Do   not   tow   aircraft   with   rudder locks installed, as severe damage to the nose steering  linkage  can  result  When  moving  the aircraft   backwards,   do   not   apply   the   brakes abruptly.      Tow   the   aircraft   slowly,   avoiding sudden    stops,    especially    over    snowy,    icy, rough,   soggy,   or   muddy   terrain.      In   arctic climates,   the   aircraft   must   be   towed   by   the main  gears,  as  an  immense  breakaway  load, resulting  from  ice,  frozen  tires,  and  stiffened grease in the wheel bearings may damage the nose gear. Do not tow or taxi aircraft with deflated shock struts. (2) Towing.    Towing  lugs  are  provided  on  the upper  torque  knee  fitting  of  the  nose  strut.    When  it  is necessary  to  tow  the  aircraft  with  a  vehicle,  use  the vehicle  tow  bar.    Never  exceed  the  turn  limit  arrows displayed   on   the   placard   located   on   the   nose   gear assembly   (fig.   2-42).      In   the   event   towing   lines   are necessary,  use  towing  lugs  on  the  main  landing  gear. Use towing lines long enough to clear nose and/or tail by at  least  15  feet.    This  length  is  required  to  prevent  the aircraft  from  overrunning  the  towing  vehicle  or  fouling the nose gear. d. Ground Handling Under Extreme Weather Conditions.      Extreme   weather   conditions   necessitate particular care in ground handling of the aircraft.  In hot, dry, sandy, desert conditions, special attention must be devoted  to  finding  a  firmly  packed  parking  and  towing area.  If such areas are not available, steel mats or an equivalent    solid    base    must    be    provided    for    these purposes. In wet, swampy areas, care must be taken to avoid bogging down the aircraft.  Under cold, icy, arctic conditions,  additional  mooring  is  required,  and  added precautions   must   be   taken   to   avoid   skidding   during towing operations. 2-104.   PARKING. Parking   is   defined   as   the   normal   condition   under which  the  aircraft  will  be  secured  while  on  the  ground. This  condition  may  vary  from  the  temporary  expedient of setting the parking brake and chocking the wheels to the more elaborate mooring procedures described under Mooring.  The proper steps for securing the aircraft must be based on the time the aircraft will be left unattended, the   aircraft   weight,   the   expected   wind   direction   and velocity,  and  the  anticipated  availability  of  ground  and air    crews    for    mooring    and/or    evacuation.        When practical,  head  the  aircraft  into  the  wind,  especially  if strong  winds  are  forecast  or  if  it  will  be  necessary  to leave the aircraft overnight.  Set the parking brake and chock the wheels securely.  Following engine shutdown, position and engage the control locks. NOTE Cowlings and loose equipment will be suitably secured at all times when left in an unattended condition. a. The     parking     brake     system     for     the     aircraft incorporates  two  lever-type  valves,  one  for  each  wheel brake.  Both valves are closed simultaneously by pulling out   the   parking   brake   handle.      Operate   the   parking brake as follows: 1. Depress both brakes. 2. Pull parking brake handle out.  This will cause the parking brake valves to lock the hydraulic fluid   under   pressure   in   the   parking   brake system, thereby retaining braking action. 3. Release brake pedals. Do not set parking brakes when the brakes are hot,    during    freezing    ambient    temperatures. Allow   brakes   to   cool   before   setting   parking brakes. 4. To release the parking brakes push in on the parking brake handle. b. The  control  lock  (fig.  2-23)  holds  the  engine  and propeller   control   levers   in   a   secure   position.      The elevator,  rudder,  and  ailerons  are  secured  in  a  neutral position. Install the control locks as follows: 1. With   engine   and   propeller   control   levers   in secure position, slide lock around the aligned control levers. 2. Install elevator and aileron lockpin through the pilot's control column to lock control wheel 3. Install  rudder  lock  pin  through  floor  mounted door,   forward   of   pilot's   seat,   making   sure rudder is in neutral position 4. Reverse  steps  1  through  3  above  to  remove control lock.  Store control lock. 2-105.   INSTALLATION OF PROTECTIVE COVERS. The  crew  will  ensure  that  the  aircraft  protective  covers are installed when leaving the aircraft. 2-94