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1、,Aircraft System Aircraft Tires,1,内容详尽,Classification of Tires Type Size Ply rating (层数） Tube or tubeless,2,内容详尽,Classification of Tires Type tire Characteristic: Low pressure, piston-power aircraft. Construction character: The section width is relatively wide in relation to the bead diameter. Desig
2、nating Method: Section width and rim diameter 9.50-16 tire: the section width is 9.5 inches, the rim diameter is 16 inches.,3,内容详尽,4,内容详尽,5,内容详尽,Classification of Tires Type tire Characteristic: Extra-high pressure, jet aircraft. Construction character: Ply rating from 4 to 38. Designating Method: O
3、utside diameter and section width 3813 tire: The outside diameter is 38 inches, the section width is 13 inches.,6,内容详尽,7,内容详尽,8,内容详尽,Classification of Tires Type tire Characteristic: Jet aircraft， high load-carrying ability,Ply rating: 4 to 38 Construction character: Low profile. Designating Method:
4、 Outside diameter, section width and rim diameter. 3011.50-14.5 tire: The outside diameter is 30 inches, The section width is 11.50 inches, The rim diameter is 14.5 inches.,9,内容详尽,Classification of Tires Designating Method: A Type VIII or three-part nomenclature tire is identified by 3 parameters: o
5、verall diameter, section width, and rim diameter. They are arranged in that order with the first two separated by an “X” and the second two separated by a “.” For example: 18 X 4.2510 designates a tire that is 18 inches in diameter with a 4.25-inch section width to be mounted on a 10- inch wheel rim
6、.,10,内容详尽,11,内容详尽,Bias or Radial Tire Another means of classifying an aircraft tire is by the direction of the plies used in construction of the tire, either bias or radial. Traditional aircraft tires are bias ply tires. The plies are wrapped to form the tire and give it strength. The angle of the p
7、lies in relation to the direction of rotation of the tire varies between 30and 60.,12,内容详尽,Bias or Radial Tire In this manner, the plies have the bias of the fabric from which they are constructed facing the direction of rotation and across the tire. Hence, they are called bias tires. The result is
8、flexibility as the sidewall can flex with the fabric plies laid on the bias.,13,内容详尽,14,内容详尽,Ply Rating It is just a strength index but in the past. Tires are given a ply rating, rather than specifying the actual number of layers of fabric material used in the carcass. The ply rating of a tire relat
9、es to its maximum static load and its inflation pressure.,15,内容详尽,Tube or Tubeless Tires Tubeless tires: one-tenth of an inch thick inner liner “TUBELESS”on the sidewall Tube tires: no inner liner, smoother inside surface. no “identification ” on the sidewall,16,内容详尽,Construction of Tire Automobile
10、and truck tires 1. different specifications from those used for aircraft tires. 2. to operate for long periods of time. 3. a relatively large but steady load at reasonably high rotational speeds 4. a relatively small amount of deflection （变形）. Car Tires: a continual deflection of only about 12 to 14
11、%.,17,内容详尽,Construction of Tire Airplane tires 1. strong enough to absorb the tremendous loads exerted on them at touchdown. 2. they must operate at very high speeds. 3. the ground roll duration is limited. 4. a deflection of between 32 and 35%, more than twice that allowed for automobile tires,18,内
12、容详尽,19,内容详尽,20,内容详尽,21,内容详尽,22,内容详尽,23,内容详尽,BEAD（胎缘） The beads are made of bundles of high-strength carbon- steel wire, with one, two, or three of these bundles used in each side of the tire. The most important part of a tire. To provides a firm mounting surface for the tire on the wheel. All of the
13、 ground forces on the tire terminate in the bead. Figure 9-71,24,内容详尽,Rubber Apex Strips (橡胶填充层) Definition: To pack and streamline the round bead bundles, so the fabric will fit smoothly around them with no voids.,25,内容详尽,Flippers（隔离层） Definition: Layers of rubber and fabric enclose the bead bundle
14、s to insulate the carcass plies from the bead wires. Function: Because the greatest amount of heat in the tire is concentrated in the bead area, this insulation increases the durability of the tire.,26,内容详尽,CARCASS and TURN-UPS （胎体和重叠层） layers or plies of rubber-coated nylon-cord fabric. the cords o
15、f the fabric at an angle of approximately 450 to the length of the strip the strips extend completely across the tire and lap back over the beads to form the ply turn-ups. each successive ply of the fabric is placed in such a way that the cords cross each other at approximately 900 to balance the st
16、rength of the carcass.,27,内容详尽,CHAFERS （胎缘包覆层） Definition: Layers of fabric and rubber wrap around the edges of the carcass plies and enclose the entire bead area. Function: They provide chafe resistance between the bead and the wheel.,28,内容详尽,UNDERTREAD （底胎面） Definition: A plies of specially compou
17、nded rubber placed over the carcass. Function: To provide good adhesion between the tread and the carcass.,29,内容详尽,TREAD REINFORCING LAYER （胎面加强层） Definition: One or more plies of nylon fabric strengthens the tread. Function: 1. to opposes the centrifugal forces that try to pull the tread from the c
18、arcass during high-speed operation.,30,内容详尽,TREAD REINFORCING LAYER （胎面加强层） 2. It also stabilizes the tread on the cord body and prevents it from squirming（蠕动) or moving. 3. This reinforcement does not enter into the ply rating of the tire, but it is used as a guide for the retreader when buffing th
19、e tire to remove the tread.,31,内容详尽,TUBELESS TIRE LINER （无内胎轮胎衬层） Definition: A special compound of rubber that is less permeable than the rubber used in the rest of the tire. a thin coating of rubber over the inner ply cords protects the liner from chafing. Function: The liner acts as a container f
20、or the air and minimizes the amount of air that seeps out through the casing plies.,32,内容详尽,TREAD （胎面） Definition: The wearing surface on the outer circumference of the tire. Characteristic: 1. It is made of specially compounded rubber. 2. A pattern of grooves molded into its surface to give the tir
21、e the required traction (附着力） according to the type of runway surface the aircraft will encounter.,33,内容详尽,34,内容详尽,TREAD PATTERNS Plain Tread Plain, or smooth, tread is used on some helicopter and on very light airplanes. All weather tread 1. All-weather treads have a rib tread in the center and dia
22、monds molded into the shoulders 2. The diamond-shaped tread pattern is effective for aircraft operating on grass or hard-packed dirt, and the rib tread in the center gives good traction on hard surfaced runways【Figure 9-72,35,内容详尽,36,内容详尽,Rib Tread The rib tread is the most popular tread pattern fou
23、nd on modern aircraft today. 1. use on hard-surfaced runways. 2. long tread wear life 3. good traction 4. exceptionally good directional stability. Figure 9-73 The width and depth of the grooves , their placement on the tread are determined by operating conditions of aircraft for which they are desi
24、gned.,37,内容详尽,38,内容详尽,CHINE(胎脊、偏转器） Chines or deflectors molded into the upper sidewall of tire on the nose wheel. Tires for dual nose wheel installations have chines on one side only, Single nose wheel installations have dual chines (deflectors)，one on either side of the tireFigure 9-74 Function: T
25、o prevent water or slush from being thrown up by the nose wheel and entering the engines， Figure 9-74,39,内容详尽,40,内容详尽,SIDEWALL Definition: A rubber covering that extends from the tread down to the bead heel Function: To protect the carcass from injuries such as cuts or bruises and from exposure to m
26、oisture and ozone.,41,内容详尽,VENT HOLES Definition: Vent holes in the lower sidewall to allow the air seeping into sidewall to escape. These holes are marked with paint and must be kept open when the tire is retreaded. Function: When the tire was heated, to avoid ply separation and the tread to be thr
27、own from the tire.,42,内容详尽,TIRE INSPECTION ON THE AIRCRAFT Most inspection on the aircraft Scheduled inspections of the tires The technician should take a look at the tires any time work is being done in the vicinity of the gear.,43,内容详尽,轮胎充气的基本要求 1. 如果将轮胎始终维持在正确压力，轮胎寿命会更长。 2. 如果用干燥的空气给轮胎充气，确保氧气含量不超
28、过5%。 3. 如果轮胎压力比正确压力低5%或更低，则为轮胎充气。 4. 如果轮胎压力比正常压力低5%15%，给轮胎充气并在24 小 时后检查。 5. 如果轮胎压力比正常压力低1530%，拆卸并更换机轮和轮胎组件。 6. 如果轮胎压力比正常压力低超过30%，拆卸并更换机轮和轮胎组件。如果轮胎在压力下降后机轮转动并承担飞机重量，更换安装在轮轴对侧的机轮和轮胎组件。,44,内容详尽,Heat Damage The greatest enemy of an aircraft tire is heat. Heat resource: 1. The heat generated within the t
29、ire as it rolls over the ground, the sidewalls flex and cause internal heat 2. The heat from external sources such as the brakes or hot runway surfaces.,45,内容详尽,Inflation Pressure 1. The pressure should be checked Daily inspection Preflight inspection 2. Differences in air pressure between dual moun
30、ted tires should cause concern. It defeats the purpose of dual mounted tires 3. Any pressure difference should be corrected and noted in the aircraft logbook. Consult the aircraft service manual to determine the exact tire pressure tolerances.,46,内容详尽,Inflation Pressure Inflation pressure should alw
31、ays be measured when the tire is cold. Two to three hours should elapse after a flight or before the pressure is measured. Tire pressure check is the most important parts of routine preventive maintenance. The pressure in the aircraft service manual, rather than that listed in the tire manufacturers
32、 product manuals. Reason: tire pressures vary from one aircraft design to another.,47,内容详尽,Inflation Pressure The pressure specified in the airframe manufacturers manual is for a loaded tire, If serviced and inflated off the aircraft, the inflation pressure should be four percent less than the press
33、ure specified. ( 180psi, 187psi in the AMM) Pressure gauges should be periodically calibrated. Inflation pressure of a tire varies with the ambient temperature by about one percent for every five degrees Fahrenheit.,48,内容详尽,Inflation Pressure 1. If a tire is inflated and allowed to stabilize with a
34、pressure of 180 psi in a shop where the temperature is 70F. 2. And the airplane is rolled outside where it remains overnight with a temperature of 0F, the pressure will drop by 14% to about 155 psi. 3. Obviously, tire would then be seriously under-inflated and should be reinflated to 180 psi.,49,内容详
35、尽,Inflation Pressure An airplane is to fly into an area where the temperature is much lower than that of the departing point. Theoretically, the pressure should be adjusted before the airplane leaves. 1. The temperature at the departing airport is 100F . 2. The airplane is to land at the another air
36、port where the temperature is 40F. 3. The pressure should be increased before takeoff.,50,内容详尽,Inflation Pressure 4. If the tire requires 187 psi, the 60F temperature drop will require the pressure to be 12greater, or 210 psi. The maximum allowable safe-inflation pressure in AMM could not been excee
37、ded. Nylon tire will stretch and increase their volume enough to cause pressure drop after they are first inflated. The pressures should be adjusted 12 to 24 hours after first installation. Conclusion: Every 5F temperature drop will require the inflation pressure to be increased 5.,51,内容详尽,Over-infl
38、ation It causes more centerline wear on the tread than that on the shoulder. When a tire is worn in this way, it has much less resistance to skidding than when its tread wears uniformly.,52,内容详尽,Over-inflation,53,内容详尽,Under-inflation It causes over deflection Excess heat within the tire. (45% deflec
39、tion, three times heat builds up in tire) Tread worn away on the shoulders more than in the center. Tires showing this pattern of wear should be carefully examined for evidence of hidden damage.,54,内容详尽,Under-inflation,55,内容详尽,TREAD CONDITION Basic strength of a tire is determined by its carcass, a
40、tire loses nothing of its strength as long as the tread does not wear down to the body plies. It should be removed for retreading while there is still at least 1/32-inch of tread left at its most shallow point.,56,内容详尽,57,内容详尽,Correct Inflation Pressure Normal Wear The correct inflation pressure wil
41、l wear the tread uniformly. Figure 9-76,58,内容详尽,59,内容详尽,Abnormal Wear of Tire Tread 1. Uneven tread wear Cause: the landing gear is out of alignment. Measures: Wheel alignment should be checked so it conforms to the specifications of the aircraft service manual. If the uneven wear is slight and the
42、landing gear is not adjusted, the tires may be removed, carefully inspected, and reversed so the wear will even out.,60,内容详尽,Abnormal Wear of Tire Tread 2 Tread wear in spots Cause: malfunctioning brakes improperly torqued bearings worn strut parts landing with brakes engaged.,61,内容详尽,Tread cut A ti
43、re should be removed form service if the tread is cut across more than one-half of a rib width Cause: glass, rock, or metal Figure 9-80 grooved runway Figure 9-82 Note: remove glass, rock, or metal with a blunt awl or screwdriver.,62,内容详尽,63,内容详尽,64,内容详尽,Tread burn A tire should be removed form serv
44、ice if the tread shows the burning mark on the contact point with the runway or water on the runway. Figure 9-81 Cause: hydroplaning (打滑） a locked brake,65,内容详尽,66,内容详尽,Inspection of Tread 1. If the cord body plies are visible, the tire cannot be retrodden. Figure 9-79 2. If the tread reinforcement
45、just is showing, the tires are possibly retrodden. 3. Any time the tread is cut more than halfway across a rib，or any of the carcass plies are exposed，the tire should be removed from serviceFigure 9-80,67,内容详尽,68,内容详尽,Inspection of Tread 4. bits of glass, rock or metal embedded in the tread should b
46、e carefully removed with a blunt awl or a small screwdriver. 5. Tires showing burn at the point of contact should be removed from service. 6. Operating on grooved runways can cause chevron-shaped (V-shape) cuts across the ribs of a tire. If they extend across more than one-half of the rib, the tire
47、should be removed from service.,69,内容详尽,Inspection of Tread 7. Any damaged or suspect area of the tire should be marked with a light-colored marker before deflating the tire. 8. Any tread damage should be carefully evaluated by a licensed retreading agency to determine whether or not the tire is rep
48、airable.,70,内容详尽,Sidewall Purpose: It protects the carcass plies from damage, either from mechanical abrasion, from deterioration by chemicals，or by the sun. 1. if small snags, cuts , weather cracks dont expose the cords, the tire should not be removed for maintenance. 2. Check for open holes on the
49、 sidewall. The vent is used to relieve the air diffused into the body plies from the tire compartment in order to protect the plies from separation.,71,内容详尽,Procedure of Tire Removal 1. jack the aircraft up. 2. when the weight is off, deflate the tire using a deflator cap. 3. removed the cover of inflation valve. 4. remove the wheel. 5. clean, inspection and repack the bearings with proper grease, protect it from damage.,72,内容详尽,Procedure of Tire Removal 6. put the wheel on a flat surface, the bead separated f