GENERAL MOUNTING INSTRUCTIONS
FROM LANDING GEAR
In order to properly track reasons for
tire removal and to take appropriate action, it is very important to have
accurate information regarding tire removal. This information helps the
retreader or repair station to make decisions concerning inspections and the
future use of the tire.
Recommended information includes:
Name of Operator
Date of dismounting
Tire part number
Tire serial number
Reason for removal
Number of tire landings
It is further recommended that removal
information accompany the tire to the repair station or retreader. The
simplest approach is to use a tag or label attached to the tire with a
self-sticking adhesive (applied to lower sidewall) or by use of heavy or nylon
Do not use staples or other metal devices for affixing tags or labels to tires
or inner tubes. Keep adhesive labels above the bead area of the tire.
A sample label is shown below.
Proper dismounting procedures simplify the
job of servicing aircraft tires, while increasing safety and reducing the
chances of damaging tires or wheels. The task of dismounting tires should not
be undertaken without proper equipment, instructions and trained personnel.
Careful attention must be given to
disassembling and handling wheel components to avoid damage to critical
surfaces. To assist in this process, wheel manufacturers publish specific
instructions in their maintenance and overhaul manuals. Follow their
recommendations and procedures to assure trouble‑free dismounting.
The same methods are essentially used for
dismounting tubeless bias, tube-type bias and radial aircraft tires. However,
radial tires have a smaller bead flat area and have a more flexible sidewall,
which requires that more attention be placed on the tooling set up. Failure to
use proper tooling designed for the particular tire size could result in
dismounting difficulties. Follow the tooling guidelines given in the next
Once tooling has been set-up, dismounting
should occur in a similar manner for both bias and radial tires, tubeless and
beginning any tire dismount, be sure to follow the instructions and
precautions published in the wheel supplier's maintenance manual.
damaged or bulge areas before deflating, using a contrasting color chalk.
deflate the tire or tube before dismounting.
caution when unscrewing valve cores. The pressure within the tire or
tube can cause a valve core to be ejected at high speed.
damage has occurred, a tire/wheel assembly should be deflated in a
a bead breaker to loosen tire beads from both wheel-half flanges.
use proper bead breaking equipment designed for separating tires from
wheel bead seats. Do not use pry bars, tire irons, or any other sharp
tools to loosen tire beads. Damage to the tire and wheel may occur.
not loosen wheel tie bolts prior to breaking the beads loose. Damage to
the mating surfaces of the wheel halves can occur.
that the adaptor rings of the ring type bead breaker have passed over
the wheel flanges and do not interfere with any wheel components.
the faces of the adaptor rings or press pads, in contact with the tire,
are free of nicks, burrs or sharp edges which could damage the tire
bead breaker ram pressure or arm pressure slowly or in a series of
sequences or jogs to allow time for the tire's beads to slide on the
of the flexible sidewalls of a radial, use of incorrect tooling or
applying pressure too rapidly can cause sidewall distortion. Heavy
distortion of the sidewall is not only harmful to the internal tire
components, but it may also begin to "roll" the beads, making
dismounting more difficult.
TO DO IF THE TIRE BECOMES FIXED TO THE WHEEL
If a tire bead rolls such that it will no
longer slide on the wheel:
a soap solution to the tire/wheel interface. Allow several minutes for the
solution to penetrate between the tire and wheel.
Note: Do not use hydrocarbon-based
lubricants. These can be harmful to the rubber components of the tire.
a reduced hydraulic pressure to the tire.
several times if necessary.
If the tire still remains fast:
the tire/wheel assembly from the machine.
the tire in a cage until the bead moves back to its correct position.
the dismounting procedure following the same procedure.
Note: Cases of bead roll over should be
reported to the retreader who will examine the tire for damage. A tire found
to have been damaged should be scrapped.
tie bolts and slide out both parts of the wheel from the tire.
tube-type tires, remove the tube.
is now dismounted.
The primary component for dismounting an
aircraft tire from its wheel is the bead breaking equipment used to loosen the
tire from the wheel bead seats.
Two types of bead breaking equipment can
be identified here:
"ring" type bead breaker.
Bead breaking is performed by
pushing a movable adapter ring against the lower sidewall of one side of the
tire. The opposite side consists of a stationary adapter ring that also
contacts the lower sidewall of the tire.
It is important
that the "adaptor" rings be designed for the particular tire/wheel
assembly to be dismounted.
condition is an adapter ring internal diameter as close to the wheel flange
diameter as possible. Pushing too high on the tire sidewall will only distort
the sidewall and bead area, making dismounting more difficult.
purposes, a radial clearance between the tip of the wheel flange and the
internal diameter of the adaptor ring is necessary to avoid interference
between the wheel and adaptor ring as it approaches and travels over the wheel
recommends a radial clearance of 0.4 inches (10mm).
(travel) of the adaptor ring should be at least four (4) inches (100mm) to
ensure complete separation of the tire from the wheel.
It is desirable
that the rings be designed such that the tire can be observed while pressure
is being applied, to ensure satisfactory ring contact and progress.
"pincher" type bead breaker
consists of two press arms which can be operated in a "pincher"
movement. At the end of each arm is a press pad in the form of a sector. An
adjustable cylinder is used to position the tire so that the sectors can be
matched to the size of the tire.
assembly is positioned such that the press pads contact the tire's lower
sidewall just above the wheel flange.
applied to break the beads. After the first sector of the tire is free, the
tire/wheel assembly is rotated and the operation is repeated (usually three
times) until all sectors of the tire are loose.
The press pads
used to push the tire are "universal" and are designed to push on
the tire close to the wheel flange. No specific tooling is required for the
different tire sizes to be handled.