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Aircraft tire and wheel assemblies must operate under high pressures in order to carry the loads imposed on them. They should be treated with the same respect that any other high pressure vessel would be given. Following the recommended procedures given throughout this manual, as well as those provided by authorities such as wheel manufacturers, air-framers and industry regulatory agencies, will minimize the risks and probabilities of injury.
In the event of a conflict between recommended procedures, be sure to contact your Petlas representative before undertaking the procedure in question.
Follow the instructions given in the section on “General Mounting Instructions For Aircraft Tires”.
Be particularly attentive when:
full inflation pressure.
Respect inflation pressures and all other safety instructions.
Remove from service tire/wheel assemblies found with one or more tie bolt nuts missing.
Follow the instructions given in the section on “General Mounting Instructions For Aircraft Tires”.
Be particularly attentive when:
full inflation pressure.
Respect inflation pressures and all other safety instructions.
Remove from service tire/wheel assemblies found with one or more tie bolt nuts missing.
It causes because of damaged runway surface. Chevron cutting is just a visual condition and don’t have a negative effect the tire performance.
Remove from service if the chevron cutting results in chunking which extends to and exposes the reinforcing or protector ply. The area of the chevron cutting is more than the tread footprint or the chevron cutting extends below a tread rib.
Locked (or almost locked) wheels during a landing on a dry runway can cause a dry braking flat spot on a tire. This is a flat scuffed surface on a part of the tread circumference.
Replace the tire that has a dry braking flat spot if the wear is more than the specified wear limits
Replace the tire if the dry braking flat spot causes out-of-balance or shimmy movements of its wheel.
Tread Chipping / Chunking remove from service if the reinforcing ply (bias) or protector ply (radial) is exposed for more than 6 cm2/ 1.0 sq. in.
Caused by tight turning. Depend on severity tire may be left on aircraft for remainder of its service life.
Structure of the tire rubber in the back or ITF in multiples of 0.5 cm from the small bubbles in the back is the emergence of the corrosion with authentication.In warm seasons of heavy loaded aircraft movements occur with long-term use of a taxi or a manufacturing defect in this region during the pressing process can stay in the blister is called the emergence of small bubbles. Bubbles remain in the back structure has no effect on the performance of rubber and rubber use is continued. Bubbles are removed from service this rubber is in ITF structures. This breakdown is similar to the larger separation of "Tread-Carcass Separation" will be discussed under the heading.
Some very high speed tires have nylon fabric reinforcement in the ribs of the tread. You will see this fabric as the tread wears. Cuts in this fabric are not necessarily a cause for tire replacement Debris on the runway can cause cuts to the tread and the sidewall of a tire. Replace a tire with cuts if:
-The cuts are into the casing plies,
-You can see the casing cords, for example when you open the cut
-The criterion for that issue is Cut Limit Criteria
Operation with low tire pressures, or the aircraft is taxied quickly for a long time. These operations can cause impact concussion or increase the rate of fatigue in the carcass.
A tire burst increases the load on the other tire(s) on the same strut. The carcass (es) of the tire(s) which receive the added load could be damaged. The burst tire and its related tire on the same axle must be removed and discarded if the aircraft has removed on the ground with a burst tire.
This condition results when, on a wet runway, the tire’s tread is progressively lifted off the runway surface. A wave of water builds up in front of a Rolling tire, allowing the tire to ride on the water and lose contact with the runway surface. Loss of traction, steering ability and braking action occurs.
This action is usually referred to as “dynamic hydroplaning.” Its occurrence is a function of water depth and aircraft speeds. The same phenomenon can result when a thin film of water on the runway mixes with the contaminants present or if the surface texture of the runway is smooth. This is called “viscous hydroplaning.” Generally the irregular condition of the runway surface is sufficient to break up this film.
Replace a tire that has a wet braking flat spot if the wear is more than the specified wear limits
Replace the tire if the wet braking flat spot causes out-of-balance or shimmy movements of its wheel.
A landing in a high cross wind can cause lateral scoring across the tread of a tire.Tight aircraft turns can cause lateral scoring on the shoulders of the tread.
With large lateral scoring damage, adjacent tears can also occur in the interface between the tread and the casing. Subsequently, during the life of the tire, the tears can be related to separation of tire components.
Replace a tire if the scoring has related tread chunking more than specified limits or cuts below a rib.
This may vary from a crack in the tire though to a tread strip.
Usually occurring on the tread area, this condition is caused by unclean runways, but may also be associated with towing bars. The tİre must be removed.
Even tread wear indicates that tire pressure has been maintained at the correct inflation level during service (see figure- 13). The tire must be removed.
When a tire has been operated with a higher pressure than required for the aircraft loads, an accentuated enterline wear will be apparent. Overinflation has reduced the number of cycles to wearout and made the tire more susceptible to bruises, cutting and shock damage (see figure14).
When a tire has consistently been operated under inflated, shoulder wear will result. Severe under inflation may cause ply separations and carcass heat build-up which can lead to thrown treads, sidewall fatigue and shorten tire life. Follow wear removal criteria (see figure 15).
This condition occurs when a tread rib partially or totally peels off in a circumferential direction. Usually beginning with a cut in the tread, it results in a circumferential delamination of a tread rib away from the tire carcass.
Remove such tires from the aircraft. In the case of transverse cuts on the tread, remove the tire if the cut is deeper than the tread groove or extends across a rib from groove to groove.
An extension of groove cracking progressing under a tread rib which can lead to tread chunking, peeled rib or thrown tread. Under side wind on a single pillar in the decline, the only place to stay hard erection occurs in the sharp turns.
Aircraft tire under the title of the ozone in the “STORAGE” section in the light of the description of the tires sidewall surfaces of the cracks are occurring capillary. Depending on the size of cracks are removed from service.
It causes because of damaged runway surface. Chevron cutting is just a visual condition and don’t have a negative effect the tire performance.
Remove from service if the chevron cutting results in chunking which extends to and exposes the reinforcing or protector ply. The area of the chevron cutting is more than the tread footprint or the chevron cutting extends below a tread rib.
Tires are designed to be tough, durable and to withstand large loads and high speeds. They can provide years of reliable service if a few precautions are followed.
Care should be shown when handling aircraft tires. While tough and durable, tires can be damaged or cut by sharp objects or if excessive force is used. Avoid lifting tires with conventional two prong forks of material handling trucks. Damage to bead mounting areas or the inner liner can occur. A wide, flat, pincher type fork assembly of the type that lifts the horizontal tire by squeezing against the tread surface is recommended. An alternate recommended method would be to use a rounded bar to lift the tire.
The ideal location for tire and tube storage is a cool, dry and reasonably dark location, free from air currents and dirt. While low temperatures (not below 0°C/32°F) are not objectionable, room temperatures above 32°C / 90° F are detrimental and should be avoided.
To aid in the control of ozone attack on rubber, the tire materials specialist adds waxes and protective chemicals. Some of these ingredients address ozone attack when the tire is in a static state at room temperature; other ingredients are activated by heat and protect the tire once it is in service. Wet or moist conditions have a deteriorating effect on tires and tubes, and can be even more damaging when the moisture contains foreign elements that are further harmful to rubber and cord fabric.
Strong air currents should be avoided, since they increase the supply of oxygen and quite often carry ozone, both of which cause rapid aging of rubber. Particular care should be taken to store tires and tubes away from fluorescent lights, electric motors, battery chargers, electric welding equipment, electric generators and similar electrical devices, since they all create ozone.
Make sure that tires do not come into contact with oil, gasoline, jet fuel, hydraulic fluids or other hydrocarbon solvents, since all of these are natural enemies of rubber and cause it to disintegrate rapidly. Be especially careful not to stand or lay tires on floors that are covered with oil or grease. When working on engines or landing gears, tires should be covered so that oil does not drip on them.
If tires accidentally become contaminated, wash them off with denatured alcohol and then with a soap and water solution. After cleaning, be sure to remove any water that may have accumulated in the interior of an unmounted tire. If after cleaning, the surface of the tire appears soft, or spongy, or bulges are present, the tire is not suitable for service.
The storage room should be dark, or at least free from direct sunlight. Windows should be darkened with a coat of blue paint or covered with black plastic. Either of these will provide some diffused lighting during the daytime. Black plastic is preferred since it will lower the temperature in the room during the warm months and permit tires to be stored closer to the window.
Fluorescent or mercury vapor lights should not be used because they generate ozone. Low intensity sodium vapor lights are recommended. See the section on “Aircraft Tires and Ozone” for more information.
Whenever possible, tires should be stored in regular tire racks which hold them up vertically. The surface of the tire rack on which the weight of the tire rests should be flat and, if possible, 3 to 4 inches wide to prevent permanent distortion of the tire.
Axial (circumferential) rotation of unmounted, vertically stored tires should not be required. With respect to the effect of storage time on rotation, we strongly suggest the use of first-in first-out (FIFO) storage. This helps to avoid overage, distortion and related field issues.
If tires are stacked horizontally, they may become distorted, resulting in mounting problems. This is particularly true of tubeless tires. Those on the bottom of a stack may have the beads pressed so closely together that bead spreader tools will have to be used to properly space the beads for contact with the wheel during initial inflation.
Tires which are stacked on top of each other, sidewall-to-sidewall, have increased stresses in the tread grooves. If tires are stored for an extended period of time, or in an environment with high ozone concentration, ozone cracking is most likely to form in the tread grooves. If tires must be stacked, they should not be stacked for more than 6 months maximum. The maximum stacking height:
- 3 tires high if tire diameter is greater than 40 inches / 1 meter.
- 4 tires high if tire diameter is less than 40 inches inches / 1 meter.
Tubes should be stored in their original cartons whenever possible. If stored without their cartons, they should be lightly lubricated with talc powder and wrapped in heavy paper.
Tubes can also be stored in matching tires. Tires should be clean and lightly lubricated with talc with tubes inflated just enough to round them out.
Under no circumstances should tubes be hung over nails, pegs or any object that might form a crease in the tube. Such a crease will eventually produce a crack in the rubber.
Once a tire has been properly mounted and the assembly verified for pressure retention, only minimal precautions need be taken
- Do not expose the tire toexcessively high temperatures (greater than 40° / 104° F)
- Do not expose the tire to direct sunlight or to high ozone concentration
- Avoid contact with contaminants (oil, grease, etc.)
- A Mounted tire / wheel assembly properly prepared and delivered to a line maintenance station as an airworthy replacement unit should meet the following storage conditions:
- To minimize the effects of ozone attack and where reinflation capability exists, tire pressure may be reduced to a value below operational pressure, but not less than 25% of the operational pressure or 40 psi / 3 bars, whichever is less.
- Transportation of a serviceable aircraft tire/wheel assembly should be in accordance with the applicable regulatory body for the airline. While serviceable tires may be shipped fully pressurized in the cargo area of an aircraft, Petlas’s recommendation is to reduce pressure to 25% of operating pressure or 3 bars / ~40 psi, whichever is the lesser. Reinflate to operating pressure before mounting on the aircraft.
Care should be shown when handling aircraft tires. While tough and durable, tires can be damaged or cut by sharp objects or if excessive force is used. Avoid lifting tires with conventional two prong forks of material handling trucks. Damage to bead mounting areas or the inner liner can occur. A wide, flat, pincher type fork assembly of the type that lifts the horizontal tire by squeezing against the tread surface is recommended. An alternate recommended method would be to use a rounded bar to lift the tire.
The ideal location for tire and tube storage is a cool, dry and reasonably dark location, free from air currents and dirt. While low temperatures (not below 0°C/32°F) are not objectionable, room temperatures above 32°C / 90° F are detrimental and should be avoided.
To aid in the control of ozone attack on rubber, the tire materials specialist adds waxes and protective chemicals. Some of these ingredients address ozone attack when the tire is in a static state at room temperature; other ingredients are activated by heat and protect the tire once it is in service. Wet or moist conditions have a deteriorating effect on tires and tubes, and can be even more damaging when the moisture contains foreign elements that are further harmful to rubber and cord fabric.
Strong air currents should be avoided, since they increase the supply of oxygen and quite often carry ozone, both of which cause rapid aging of rubber. Particular care should be taken to store tires and tubes away from fluorescent lights, electric motors, battery chargers, electric welding equipment, electric generators and similar electrical devices, since they all create ozone.
Make sure that tires do not come into contact with oil, gasoline, jet fuel, hydraulic fluids or other hydrocarbon solvents, since all of these are natural enemies of rubber and cause it to disintegrate rapidly. Be especially careful not to stand or lay tires on floors that are covered with oil or grease. When working on engines or landing gears, tires should be covered so that oil does not drip on them.
If tires accidentally become contaminated, wash them off with denatured alcohol and then with a soap and water solution. After cleaning, be sure to remove any water that may have accumulated in the interior of an unmounted tire. If after cleaning, the surface of the tire appears soft, or spongy, or bulges are present, the tire is not suitable for service.
The storage room should be dark, or at least free from direct sunlight. Windows should be darkened with a coat of blue paint or covered with black plastic. Either of these will provide some diffused lighting during the daytime. Black plastic is preferred since it will lower the temperature in the room during the warm months and permit tires to be stored closer to the window.
Fluorescent or mercury vapor lights should not be used because they generate ozone. Low intensity sodium vapor lights are recommended. See the section on “Aircraft Tires and Ozone” for more information.
Whenever possible, tires should be stored in regular tire racks which hold them up vertically. The surface of the tire rack on which the weight of the tire rests should be flat and, if possible, 3 to 4 inches wide to prevent permanent distortion of the tire.
Axial (circumferential) rotation of unmounted, vertically stored tires should not be required. With respect to the effect of storage time on rotation, we strongly suggest the use of first-in first-out (FIFO) storage. This helps to avoid overage, distortion and related field issues.
If tires are stacked horizontally, they may become distorted, resulting in mounting problems. This is particularly true of tubeless tires. Those on the bottom of a stack may have the beads pressed so closely together that bead spreader tools will have to be used to properly space the beads for contact with the wheel during initial inflation.
Tires which are stacked on top of each other, sidewall-to-sidewall, have increased stresses in the tread grooves. If tires are stored for an extended period of time, or in an environment with high ozone concentration, ozone cracking is most likely to form in the tread grooves. If tires must be stacked, they should not be stacked for more than 6 months maximum. The maximum stacking height:
- 3 tires high if tire diameter is greater than 40 inches / 1 meter.
- 4 tires high if tire diameter is less than 40 inches inches / 1 meter.
Tubes should be stored in their original cartons whenever possible. If stored without their cartons, they should be lightly lubricated with talc powder and wrapped in heavy paper.
Tubes can also be stored in matching tires. Tires should be clean and lightly lubricated with talc with tubes inflated just enough to round them out.
Under no circumstances should tubes be hung over nails, pegs or any object that might form a crease in the tube. Such a crease will eventually produce a crack in the rubber.
Once a tire has been properly mounted and the assembly verified for pressure retention, only minimal precautions need be taken
- Do not expose the tire toexcessively high temperatures (greater than 40° / 104° F)
- Do not expose the tire to direct sunlight or to high ozone concentration
- Avoid contact with contaminants (oil, grease, etc.)
- A Mounted tire / wheel assembly properly prepared and delivered to a line maintenance station as an airworthy replacement unit should meet the following storage conditions:
- To minimize the effects of ozone attack and where reinflation capability exists, tire pressure may be reduced to a value below operational pressure, but not less than 25% of the operational pressure or 40 psi / 3 bars, whichever is less.
- Transportation of a serviceable aircraft tire/wheel assembly should be in accordance with the applicable regulatory body for the airline. While serviceable tires may be shipped fully pressurized in the cargo area of an aircraft, Petlas’s recommendation is to reduce pressure to 25% of operating pressure or 3 bars / ~40 psi, whichever is the lesser. Reinflate to operating pressure before mounting on the aircraft.
