TM 1-1510-218-10 2-20 the  floor  and  is  used  when  an  alternate  extension  of the gear is required.  Refer to Figure 2-10. To engage the system, pull the LANDING GEAR CONTROL  circuit  breaker,  located  on  the  overhead circuit breaker panel, and ensure that the  LDG GEAR CONTROL D2 T1 or LDG GEAR CONTR T2 handle is in the  DN  position.   Remove  the  extension  lever  from the securing clip and pump the lever up and down until the three green   D2 T1 or  NOSE / L / R  T2 gear down indicator  lights  illuminate.    As  the  handle  is  moved, hydraulic  fluid  is  drawn   from  the  hand  pump  suction port  of  the  power  pack  and  routed  through  the  hand pump    pressure    port    to    the    actuators.        After    an alternate  extension  of  the  landing  gears,  ensure  the extension  lever  is  in  the  full  down  position  prior  to stowing the pump handle  in  the  retaining  clip.   When the pump handle is stowed, an internal relief valve is actuated to relieve the hydraulic pressure in the pump. After an emergency landing gear extension has  been  made,  do  not  move  any  landing gear   controls,   or   reset   any   switches  or circuit   breakers   until   the   aircraft   is   on jacks,  since  the  failure  may  have  been  in the   gear-up   circuit   and   the   gear   might retract on the ground. NOTE If    for    any    reason    the    green    NOSE-L-R GEAR  DOWN  indicators  do  not  illuminate (e.g.,    in    case    of    an    electrical    system failure),  continue  pumping  until  sufficient resistance is felt to ensure that the gear is down    and    locked.         Do    not    stow    the extension  lever,  but  leave  it  in  the  full  up position. After   a   practice   alternate   extension,   stow   the extension handle, reset the LANDING GEAR CONTROL circuit breaker, and retract the gear in the normal manner with the landing gear control handle. i.    Tires.  (1)   C  C-12C  aircraft  are  equipped  with  dual 18  x  5.5,  8  ply  rating  tubeless  rim  inflation  tires  on each  main  gear  and a 6.50 x 10, 6 ply rating tubeless tire on the nose wheel. (2)   D     T The     C-12D/T1/T2     aircraft     are equipped with dual 22 x 6.75 x 10, 8-ply rated tubeless rim inflation tires on each main gear and a 22 x 6.75 x 10, 8-ply rated tubeless tire on the nose wheel. 2-9.  STEERABLE NOSE WHEEL. The  aircraft  can  be  maneuvered  on  the  ground by  the  steerable  nose  wheel  system.    Direct linkage from   the   rudder   pedals   to   the   nose   wheel   steering linkage  allows  the  nose  wheel  to  be  turned  12°  to  the left  of  center  or  14°  to  the  right.    When  rudder  pedal steering   is   augmented   by   the   main   wheel   braking action,  the  nose  wheel  can  be  deflected  up  to  48° either   side   of   center.      Shock   loads,   which   would normally   be   transmitted   to   the   rudder   pedals,   are absorbed   by   a   spring   mechanism   in   the   steering linkage.    Retraction  of  the  landing  gear  automatically centers  the  nose  wheel  and  disengages  the  steering linkage from the rudder pedals.  Refer to Figure 2-10. WARNING