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.
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.
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.
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.
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.
The following list outlines some of the
conditions which can disqualify a tire from being retreaded:
injuries to the beads or in the bead area (except injuries limited to the
bead cover or finishing strip).
checking or ozone cracking of tread or sidewall that results in exposed
bead wire or kinked bead.
damage or broken cords.
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.
that penetrate the innerliner.
brake heat damage, such as that experienced in an aircraft rejected
that are heavily oil soaked.
that have experienced a major pressure loss.
The following are acceptable when
retreading aircraft tires:
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.
Area - Minor injuries to the bead area may
be repaired provided the carcass plies are not damaged.
- Innerliner surface damage may be repaired (bias tires).
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