(b) Rip Panels  (4)  Controls and Auxiliaries  (a) Valve Controls  1.  Before take-of.f, crack all valves  6pen  for a  short instant to make  ce~tain  that the valves  and telltale lights operate satisfactorily.  2.  When flying close to pressure height, pull  closing control of gas valves from t ime to time.  The rope which opens the forward rip panel can be  reached from •the forward door; the rope which opens the  aft panel can be reached from the aft door.  They are  dyed red to avoid confusion with the other ropes.  The air and gas release valves can be operated  man~  ually from the pilot’s instrument panel, Fig. XI.  Every  valve has an opening arid a closing control.  Pulling the  opening control lifts the valve off its seat and releases  air or gas as the case may be.  The valves should close by  themselves when the opening control is released.  A closing control is provided, however, to force the  valves closed in case they should stick.  The control is  also used to make certain that the gas valves are closed,  and that no gas is being lost when flying near pressure  height.  The following check procedure of the valves is  recommended:  -41-