Retreading and repairing aircraft tires

Many aircraft tires that become injured in service can be successfully repaired. Tires of which the treads are worn out, flat spotted, or otherwise damaged, but of which the cord body is intact, can be retreaded. Retreading and repairing aircraft tires has been a common practice for many years and can save aircraft operators considerable sums of money. Tires that might otherwise have been discarded due to insufficient or damaged tread can be retreaded or repaired for continued service, at a cost much lower than that of a new tire. Retreading and repairing extends the service life of a carcass several times past initial new tire usage.

FAA / JAA Regulations require retreading and/or repairing of aircraft tires to be performed in certified retread and repair stations by or under the responsibility of qualified/ certified technicians. Repairs by unauthorized sources are not recommended.

Skytreads meets or exceeds all testing requirements of the FAA or JAA for retreaded aircraft tires.

RETREADING AIRCRAFT TIRES

For aircraft tires, the term "retreading" refers to the methods of restoring a used retreadable tire by renewing the tread alone or by renewing the tread plus the reinforcing ply(s) or protector ply.

Full recapping is the recommended procedure for tires with evenly worn tread, tires with flat‑spotted tread, or tires with numerous cuts in the tread area. The new tread material extends around and over the shoulder of the tire for several inches.

ACCEPTING AIRCRAFT TIRES FOR RETREADING

Accepting tires for retreading requires careful inspection of all components of the tire. Each individual tire is inspected by visual and air needle techniques prior to, during, and after the retreading process. Holographic inspection can also be used to inspect for internal defects which may limit the retreadability of a carcass.

Inspections must meet approved process limitations for that tire to be retreaded.

REPAIRING AIRCRAFT TIRES

Many tires with injuries or damages can be repaired at the time of retreading and put back into useful/ safe service. Injuries must be within the manufacturer's repairable limits.

Tires with sidewall cuts, snags, scuffs and cracking from ozone can remain in service if the carcass ply is not exposed. Damages that expose carcass textile can be repaired by an approved repair station if the cords are not cut or damaged.

Note: Repairable limits generally exceed serviceability limits used to remove tires from service. Detailed, safe inspections suitable for determining the gravity of an injury cannot be made on inflated, mounted tires. Service removal limits are further set to ensure safe operation and retreadability of the casing.

NON-REPAIRABLE AIRCRAFT TIRES

The following list outlines some of the conditions which can disqualify a tire from being retreaded:

  1. Any injuries to the beads or in the bead area (except injuries limited to the bead cover or finishing strip).
  2. Weather checking or ozone cracking of tread or sidewall that results in exposed body cords.
  3. Protruding bead wire or kinked bead.
  4. Ply separation.
  5. Internal damage or broken cords.
  6. Flat spots and skid burns that have penetrated to the top carcass ply. Wearing the tire beyond the protector ply or reinforcing plies can leave insufficient interface rubber to allow retreading.
  7. Punctures that penetrate the innerliner.
  8. Excessive brake heat damage, such as that experienced in an aircraft rejected takeoff.
  9. Tires that are heavily oil soaked.
  10. Tires that have experienced a major pressure loss.

REPAIRABLE AIRCRAFT TIRES

The following are acceptable when retreading aircraft tires:

  1. Tread Area - The size of cuts and/or other tread injuries that can be repaired during retreading is dependent on many factors, including the injury's length, depth and width as related to the tire size itself. In the absence of specific documentation, injuries 1 1/2 inches long and 1/4 inch or less in width, as measured at the first cord body ply which do not extend through more than 40% of the actual tire cord plies are repairable.

These limits are general guidelines. Authorized repair stations must insure that the retreaded tire meets all regulatory body and customer's requirements as applicable.

Repair limits for specific radial tire sizes are available from Michelin to users and authorized repair stations retreading Michelin radial tires.

  1. Bead Area - Minor injuries to the bead area may be repaired provided the carcass plies are not damaged.
  2. Innerliner - Innerliner surface damage may be repaired (bias tires).
  3. Sidewall Rubber Surface defects on large commercial tires may be repaired provided the repair is at least 1 inch from the bead heel, and no greater than an area 1 1/2 inches by 4 inches, and does not penetrate or damage the carcass ply

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