Tube Construction and Selection Tube Storage and Inspection Tire Inspection  Tire Mounting A licensed technician is often called upon to mount an  aircraft tire onto the wheel rim in preparation for service. In  the case of a tube-type tire, the tube must also be mounted.  The following section presents general procedures for these  operations using tube-type and tubeless tires. Be sure to  have the proper equipment and training to perform the work  according to manufacturer’s instructions. An aircraft tube must be inspected for leaks and damage that  may eventually cause a leak or failure. To check for leaks,  remove the tube from the tire. Inflate the tube just enough to  have it take shape but not stretch. Immerse a small tube in a  container of water and look for the source of air bubbles. A  When handling and storing aircraft tire tubes, creases are to  be avoided. These weaken the rubber and eventually cause  tube failure. Creases and wrinkles also tend to be chafe points  for the tube when mounted inside the tire. Never hang a tube  over a nail or peg for storage. It is important to inspect the inside of a tube-type tire before  installing a tube for service. Any protrusions or rough areas  should be cause for concern, as these tend to abrade the tube  and may cause early failure. Follow the tire, tube, and aircraft  manufacturer’s inspection criterion when inspecting aircraft  tires and tubes. An aircraft tire tube should be kept in the original carton until  put into service to avoid deterioration through exposure to  environmental elements. If the original carton is not available,  the tube can be wrapped in several layers of paper to protect it.  Alternately, for short time periods only, a tube may be stored  in the correct size tire it is made for while inflated just enough  to round out the tube. Application of talc to the inside of the  tire and outside of the tube prevents sticking. Remove the  tube and inspect it and the tire before permanently mounting  the assembly. Regardless of storage method, always store  aircraft tubes in a cool, dry, dark place away from ozone  producing equipment and moving air.  If an area of a tube experiences chafing to the point where  the rubber is thinned, the tube should be discarded. The  inside diameter of the tube should be inspected to ensure it  has not been worn by contact with the toe of the tire bead.  Tubes that have taken an unnatural set should be discarded.  [Figure 13-152] There is no mandatory age limit for an aircraft tire tube. It  should be elastic without cracks or creases in order to be  consider serviceable. The valve area is prone to damage and  should be inspected thoroughly. Bend the valve to ensure  there are no cracks at the base where it is bonded to the tire  or in the area where it passes through the hole in the wheel  rim. Inspect the valve core to ensure it is tight and that it  does not leak.  Tubes come in a wide range of sizes. Only the tube specified  for the applicable tire size must be used. Tubes that are too  small stress the tube construction.  Aircraft tire tubes are made of a natural rubber compound.  They contain the inflation air with minimal leakage.  Unreinforced and special reinforced heavy-duty tubes are  available. The heavy-duty tubes have nylon reinforcing fabric  layered into the rubber to provide strength to resist chafing  and to protect against heat such as during braking.  large tube may require that water be applied over the tube.  Again, look for the source of bubbles. The valve core should  also be wetted to inspect it for leaks. 13-89 Figure 13-152.  During inspection, an aircraft tire tube should retain its natural contour. Tubes with thinned areas or that have taken  a set should be discarded and replaced.  A. Natural contour B. Taking a Set C. Thinned out at edges