In the tire shop, you should recheck tires for complete deflation before disassembling the wheel and breaking the bead of the tire. Breaking the bead means separating the bead of the tire from the wheel flange. When a tire has been completely deflated and set aside to await the bead-breaking operation, the valve core should be removed and a deflated tire tag installed on the valve stem. The tire tags should be so constructed as not to be installable unless the valve core has been removed. Refer to figure 11-5.

BREAKING THE BEAD. The use of proper equipment for breaking the bead of the tire away from the wheel flange will save materials and man-hours. Aircraft tires, inner tubes, and wheels can be damaged beyond repair by improper mounting and dismounting equipment and procedures. Always refer to the applicable manufacturers operating manual prior to using this equipment. The equipment shown in figure 11-18 is recommended in NAVAIR 04-10-506. Other commercially available or locally fabricated equipment that uses either a hydraulically actuated cylinder or a mechanically actuated device may also be used, provided the equipment will not damage the tires or wheels. The bead-breaking equipment shown in figure 11-18 is available in two models. The Lee-I model is designed for use at shore-based facilities. The Lee-IX model is an explosionproof version of the Lee-I, and is intended for shipboard use.

An example of the steps used for bead breaking using the Lee-I equipment follows:

2. Determine the type and size of the wheel to be dismounted, and assemble the proper parts on the drive shaft.

3. Push the outer centering rollers toward the front of the machine, and roll the wheel (positioned with the lockring side facing outward for remountable flange wheels) on the outer centering rollers. You should use the up and down push buttons to raise or lower the drive shaft to the proper height for the wheel being dismounted. Push the wheel onto the drive shaft. If an open-rimmed tire assembly is being dismounted, omit step 4 and proceed to step 5.

4. Insert the locking bar and turn it about 90 degrees counterclockwise. Mount the wheel cone on the locking bar and insert the locking pin.

5. Push the air valve switch to the right. This will clamp the wheel on the drive shaft.

Figure 11-19.Using bead-breaking pump.

6. Use the UP push button to raise the center of the wheel to line up with the center of the bead-breaking disc.

7. Rotate the tire by pushing the tire rotating toggle to the right. Position the front bead-breaking disc against the outside bead of the wheel flange. You should adjust the position of the hydraulic pump assembly by loosening the position lockpin and sliding the pump to the proper position. After turning the pump release valve clockwise as far as it will go, apply hydraulic pressure against the bead by pumping the handle, as shown in figure 11-19. Use the guide handle to properly position the disc. Push the bead back far enough to allow the removal of the lockring or loose flange.

8. Remove the lockring and loose flange. You should use the bead shoes to hold the bead back while you are removing the lockring. See figure 11-20. Release and retract the front bead-breaking disc by turning the release valve counterclockwise.

9. Repeat the bead-breaking operation against the rear surface of the tire with the rear bead-breaking assembly.

Figure 11-20.Shaft arranged to hold tire bead while removing lockring.

DISMOUNTING DIVIDED (SPLIT) WHEELS. The tire bead should be broken away from the wheel and the nuts and bolts removed according to the bead-breaking procedure. If the tire has a tube, remove the hex nut and push the valve away from the seated position. This will prevent damage to the inner tube valve attachment when you break the tire bead loose. Then, remove the wheel assembly from the tire. If the tire is tubeless, remove the wheel seal carefully from the wheel half and place it on a clean surface. Wheel seals in good condition may be reused if replacement seals are not available. If the tire has a tube, remove it. Inner tubes can be reused if they are in good condition and less than 5 years old.