Firefly Slide Show

Plastic Wheels Pinching Tubes

After 438 take off and landings, one of the four inch Azusalite wheels pinched and tore a hole through the tube. Tom Olenik of Olenik Aviation said (Kolb Email List) that one should not go over 20 psi inflation pressure when using these wheels. But Azusa (bottom of page) cautions against going over 25 psi inflation pressure. A call to Azusa revealed that the 25 psi is precautionary, and that if the wheels are not abused they will take higher pressures, such as, 30 psi. But as the inflation pressure goes up the wheel's ability to handle a side load goes down.

To reduce the tube pinching possibility, a boot was cut from the inner circumference of the ruined tube and painted with contact cement.

On inspecting the wheels, I found sharp edges and rough protrusions on the surfaces under which the tube touches and where the two wheel halves come together. Using a fine flat file the surface was smoothened and the corner was rounded.

The boot was stuck to the inner portion of the new tube that would face the split in the rim. After I had done this "mark - twinstar - s.e. mn." responded to the Kolb Email List stating that he used duct tape and it worked well.

I will be taking the other wheel off to remove the tire and to check for the same problem. If the old tube is not too far gone or I have to purchase a new tube, I will use duct tape. It should be lighter and simpler solution to the problem.