Inner Tubes

Aircraft tubes are made of natural rubber and are made slightly undersize, so they fill fit easily into a new tyre. Aircraft tyre plies are made of nylon, and tyres will “grow” slightly, in service. The tube will also grow, and will eventually take a permanent set to the (now) larger inside tyre dimension.

If this now-larger tube is later put into a new tyre, it may be too large for the inside-tyre cavity, with the result that the tube may have folds in it. In service, these folds may eventually wear through and destroy the tube’s ability to hold air.

A slow wearing through will result in a slow leakage of air, and the pilot will be alerted to the problem before it becomes too serious. However, if the tube is torn in a particular takeoff, the tyre will probably go flat in mid-air, without the pilot having realized what is wrong. Considering the risks in reinstalling a used inner tube, we recommend a new tube be installed in a new tyre.