飞机液压系统管路和接头

1、Basic Aircraft system-AMT106 Guangzhou Civil Aviation College,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES A single aircraft typically contains several different types of rigid fluid lines. Each type of line has a specific application. However, as a rule, rigid tubing is used in: Statio

2、nary applications Long, relatively straight runs Systems that typically utilize rigid tubing include fuel, oil, oxygen, and instrument systems.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES MATERIAL 1. Rigid lines in early aircraft Many fluid lines used in early aircraft were made of cop

3、per tubing. However, copper tubing proved troublesome because it became hard and brittle from the vibration encountered during flight, and eventually failed. To help prevent failures and extend the life of copper tubing, it must be periodically annealed to restore it to a soft condition.,Basic Aircr

4、aft Systems Hydraulic System,RIGID FLUID LINES MATERIAL 1. Rigid lines in early aircraft Annealing is accomplished by heating the tube until it is red hot and then quenching in cold water. When working on an aircraft that has copper tubing, the tubing should be annealed each time it is removed. Furt

5、hermore, copper lines must be regularly inspected for cracks, hardness, and general condition.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES MATERIAL 2. Rigid lines in modern aircraft Aluminum alloy （铝合金） Corrosion-resistant steel （耐腐蚀钢） Titanium alloy （钛合金） Aluminum tubing: Aluminum tub

6、ing comes in a variety of alloys. pure aluminum tubing made from 1100-H14 (half-hard), or aluminum alloy 3003-H14 (half-hard) low pressure systems (below 1,000 psi) such as those used for instrument air or ventilating air,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES MATERIAL 2. Rigid li

7、nes in modern aircraft Aluminum tubing : lines made of 5052-O aluminum alloy Low pressure fuel and oil and medium pressure (1,000 to 1,500 psi) hydraulic and pneumatic systems. This alloy, even in its annealed state, is about one and three-quarters times stronger than half-hard, commercially pure al

8、uminum. Occasionally, 2024-T aluminum alloy is used for fluid lines because of its higher strength. However, it is not as flexible and, therefore, is more difficult to bend and flare without cracking.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES MATERIAL 2. Rigid lines in modern aircraf

9、t Aluminum tubing : Aluminum alloy tubes are identified in a number of ways. on larger tubes, the alloy designation is stamped directly on the tubes surface. on small tubing, the alloy designation is typically identified by a colored band. These color bands are no more than 4 inches wide and are pai

10、nted on the tubes ends and mid section. When a band consists of two colors, one-half the width is used for each color. Figure 10-1,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES 2. Rigid lines in modern aircraft Corrosion-resistant steel tubing : Corrosion-resistant steel tubing, either a

11、nnealed or 1/4 hard, is used in high pressure systems (3,000 psi) Applications include high pressure hydraulic, pneumatic and oxygen systems. Corrosion-resistant steel is also used in areas that are subject to physical damage from dirt, debris, and corrosion caused by moisture, exhaust fumes, and sa

12、lt air. Such areas include flap wells and external brake lines.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES 2. Rigid lines in modern aircraft Corrosion-resistant steel tubing : Another benefit of corrosion-resistant steel tubing is that it has a higher tensile strength which permits th

13、e use of tubing with thinner walls. As a result, the installation weight is similar to that of thicker-walled aluminum alloy tubing.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES 2. Rigid lines in modern aircraft Titanium alloy tubing : This type of tubing and fitting is used extensively

14、 in transport category and high performance aircraft hydraulic systems for pressures above 1,500 psi. Titanium is 30 percent stronger than steel and 50 percent lighter than steel. Cryofit fittings（冷装配接头） or swaged fittings（型锻接头） are used with titanium tubing.,Basic Aircraft Systems Hydraulic System,

15、RIGID FLUID LINES 2. Rigid lines in modern aircraft Titanium alloy tubing : Do not use titanium tubing and fittings in any oxygen system assembly. Titanium and titanium alloys are oxygen reactive. If a freshly formed titanium surface is exposed in gaseous oxygen, spontaneous combustion could occur a

16、t low pressures.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Identification of tube material Repairs to aircraft tubing must be made with materials that are the same as the original, or are an approved substitute. One way to ensure that a replacement is made of the same material is to

17、compare the code markings on the replacement tube to those on the original. If the manufacturers markings are difficult or impossible to read, an alternative method of identification must be used.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Identification of tube material While aluminu

18、m alloy and steel tubing are readily distinguished from one another, it is often difficult to determine whether a material is carbon steel or stainless steel, or whether it is 1100, 2024, 3003, or 5052 aluminum alloy. For this reason, samples of tubing can be tested for hardness, magnetic properties

19、, and reaction to concentrated nitric acid. Figure 10-2,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Identification of tube material Hardness is tested by filing or scratching a material with a scriber, whereas a magnet distinguishes between annealed austenitic and ferritic stainless st

20、eels. Typically, the austenitic types are nonmagnetic, whereas the straight chromium carbon and low-alloy steels are strongly magnetic. Since stainless steel resists corrosion caused by nitric acid, a sample of tubing that corrodes when acid is applied is a carbon, nickel, or copper alloy steel. Nit

21、ric acid attacks these alloys at different rates and yields different colors in the corrosion product. Figure 10-2,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES 18/10和18/8 不锈钢, 成份是18%的镉和8%的镍 Monel 铜-镍合金钢,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES SIZE DESIGNATIONS The size

22、 of rigid tubing is determined by its outside diameter in increments of 1/16 inch. Therefore, a -4 B nut tubing is 4/16 or 1/4 inch in diameter. A tube diameter is typically printed on all rigid tubing. Another important size designation is wall thickness, since this determines a tubes strength. Lik

23、e the outside diameter, wall thickness is generally printed on the tube in thousandths of an inch.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES SIZE DESIGNATIONS One dimension that is not printed on rigid tubing is the inside diameter. However, since the outside diameter and wall thickn

24、ess are indicated, the inside diameter is determined by subtracting twice the wall thickness from the outside diameter. For example, if you have a piece of -8 tubing with a wall thickness of 0.072 inches, you know the inside diameter is .356 inches, 0.5 - (2 x .072) = 0.356.,Basic Aircraft Systems H

25、ydraulic System,RIGID FLUID LINES FABRICATING RIGID TUBING When it is necessary to replace a rigid fluid line, you may obtain a replacement tube assembly from the aircraft manufacturer or fabricate a replacement in the shop. Most shops have the necessary tools to fabricate replacement lines, and as

26、a technician you must be familiar with their operation and limitations.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE CUTTING When cutting a new piece of tubing, you should always cut it approximately 10 percent longer than the tube being replaced. This provides a margin of safety f

27、or minor variations in bending. After determining the correct length, cut the tubing with either a fine-tooth hacksaw（细齿钢锯） or a roller-type tube cutter. （辊子型切管器）,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE CUTTING A tube cutter is most often used on soft metal tubing such as copp

28、er, aluminum, or aluminum alloy. However, they are not suitable for stainless-steel tubing because they tend to work harden the tube.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE BENDING Some applications require rigid lines with complex bends and curves. When duplicating these lin

29、es, you must be able to produce bends that are 75 percent of the original tube diameter and free of kinks. Any deformation in a bend affects the flow of fluid.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE BENDING Tubing under 1/4 inch made of soft metal and having a thin wall can u

30、sually be bent by hand. This is accomplished by using a tightly wound steel coil spring that fits snugly around the tubing to keep it from collapsing. In an emergency, a tube can be bent by first packing it full of clean, dry sand, sealing the ends, and then making the bends. However, when using thi

31、s method, it is extremely important that every particle of sand be removed from the tube before it is installed.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE BENDING Tubing larger than 1/4 inch in diameter typically requires bending tools to minimize flattening and distortion. Smal

32、l diameter tubing of between 1/4 inch and 1/2 inch can be bent with a hand bending tool. Production bending is done with a tube bender similar to the one illustrated in Figure 10-7.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE FLARING （管路喇叭口） Much of the rigid tubing used in modern

33、 aircraft is connected to components by flaring the tube ends and using flare-type fittings. A flared-tube fitting consists of a sleeve and a B-nut. Using this type connector eliminates damage to the flare caused by the wiping or ironing action（摩擦和挤压） as the nut is tightened. The sleeve provides add

34、ed strength and supports the tube so that vibration does not concentrate at the flare. Figure 10-8,Fitting,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE FLARING （管路喇叭口） The nut fits over the sleeve and, when tightened, draws the sleeve and flare tightly against a male fitting to for

35、m a seal. The close fit between the inside of the flared tube and the flare cone of the male fitting provides the actual seal. Therefore, these two surfaces must be absolutely clean and free of cracks, nicks, and scratches. Aircraft fittings have a flare angle of 37 degrees and are not interchangeab

36、le with automotive-type fittings, which have a flare angle of 45 degrees. Figure 10-8,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE FLARING （管路喇叭口） There are two types of flares used in aircraft plumbing Systems （管道系统）： 1. single flare 2. double flare As discussed, the flare provide

37、s the sealing surface and is subject to extremely high pressures. Because of this, flares must be properly formed to prevent leaks or failures. Figure 10-9,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE FLARING Instructions for Rolling-Type Flaring Tools 1. Use these tools only to fl

38、are soft copper, aluminum, and brass tubing. 2. Do not use with corrosion resistant steel or titanium. 3. Cut the tube squarely and remove all burrs. Slip the fitting nut and sleeve on the tube. 4. Loosen clamping screw used for locking the sliding segment in the die holder. This will permit their s

39、eparation.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE FLARING Instructions for Rolling-Type Flaring Tools 5. The tools are self-gauging; the proper size flare is produced when tubing is clamped flush with the top of the die block. 6 . Insert tubing between the segments of the die

40、 block that correspond to the size of the tubing to be flared. Advance the clamp screw against the end segment and tighten firmly. 7. Move the yoke down over the top of the die holder and twist it clockwise to lock it into position.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE FLAR

41、ING Instructions for Rolling-Type Flaring Tools 8. Turn the feed screw down firmly, and continue until a slight resistance is felt. This indicates an accurate flare has been completed. 9. Always read the tool manufacturers instructions, because there are several different types of rolling-type flari

42、ng tools that use slightly different procedures.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES TUBE FLARING A flare which is made too small produces a weak joint, and may leak or pull apart. On the other hand, if a flare is too large it may interfere with the installation of the nut and

43、result in leakage. In either case, if a fitting leaks when properly torqued, you should inspect the flare and fitting components for proper manufacture and assembly. Do not overtighten a leaky fitting.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES DOUBLE FLARING Soft aluminum tubing with

44、 an outside diameter of 3/8 inch or smaller can be double-flared to provide a stronger connection. A double flare is smoother and more concentric than a single flare and, therefore, provides a better seal. Furthermore, a double flare is more durable and resistant to the shearing effect of torque. Fi

45、gure 10-13,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES DOUBLE FLARING 1. To double-flare a piece of tubing, cut it off in the same manner as a single-flare, remove all burrs, and polish the end. 2. Next, insert the tubing into the flaring die to the depth allowed by the stop pin and th

46、en clamp the dies. 3. Insert the upsetting tool into the die and, with as few blows of a hammer as possible, upset（镦锻） the tubing. 4. Once the flare is started, insert the flaring tool and strike it with a hammer to fold the metal down into the tubing and form the double flare.,Basic Aircraft System

47、s Hydraulic System,RIGID FLUID LINES Presetting of Flareless Fitting Although the use of flareless tube fittings eliminates all tube flaring, another operation, referred to as presetting, is necessary prior to installation of a new flareless tube assembly. Flareless tube assemblies should be preset

48、with the proper size presetting tool or operation.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Presetting of Flareless Fitting Figure.7-11 (steps 1, 2, and 3) illustrates the presetting operation,which is performed as follows: 1. Cut the tube to the correct length, with the ends perfec

49、tly square. Deburr the inside and outside of the tube. 2.Slip the nut, then the sleeve, over the tube (step 1), lubricate the threads of the fitting and nut with hydraulic fluid.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Presetting of Flareless Fitting Figure.7-11 (steps 1, 2, and 3)

50、 illustrates the presetting operation,which is performed as follows: 3. Place the fitting in a vise (step 2), and hold the tubing firmly and squarely on the seat in the fitting. (The tube must bottom firmly in the fitting.) Tighten the nut until the cutting edge of the sleeve grips the tube. 4.To de

51、termine this point, slowly turn the tube back and forth while tightening the nut. When the tube no longer turns, the nut is ready for tightening.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Presetting of Flareless Fitting Final tightening depends upon the tubing (step 3). For aluminum

52、alloy tubing up to and including 12 outside diameter, tighten the nut from 1 to 116 turns. For steel tubing and aluminum alloy tubing over 12 outside diameter, tighten from 116 to 112 turns.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Inspection of Flareless Fitting After presetting th

53、e sleeve, disconnect the tubing from the fitting and check the following points: 1. The tube should extend 332“ to 18” beyond the sleeve pilot; otherwise, blowoff may occur. 2. The sleeve pilot（导向套筒） should contact the tube or have a maximum clearance of 0.005“ for aluminum alloy tubing or 0.015” fo

54、r steel tubing. 3. A slight collapse of the tube at the sleeve cut is permissible. No movement of the sleeve pilot, except rotation, is permissible.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Fluid Line Identification Fluid lines in aircraft are often identified by markers made up of

55、color codes, words, and geometric symbols. These markers identify each lines function, content, and primary hazard. Figure 7-13 illustrates the various color codes and symbols used to designate the type of system and its contents.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Fluid Line

56、Identification Fluid lines are marked, in most instances with 1 tape or decals, as shown in Figure 7-14(A). On lines 4 in diameter (or larger), lines in oily environment, hot lines, and on some cold lines, steel tags may be used in place of tape or decals, as shown in Figure 7-14(B). Paint is used o

57、n lines in engine compartments, where there is the possibility of tapes, decals, or tags being drawn into the engine induction system.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Fluid Line Identification In addition to the above-mentioned markings, certain lines may be further identif

58、ied regarding specific function within a system; for example, drain, vent, pressure,or return. Lines conveying fuel may be marked FLAM. lines containing toxic materials are marked TOXIC in place of FLAM. Lines containing physically dangerous.,Figure 10-23. To help absorb the stress caused by vibrati

59、on, tubing should have at least one bend.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINES Rigid Tubing Installation and Inspection Before installing a line assembly in an aircraft, inspect the line carefully. Remove dents（ 凹痕） and scratches, and be sure all nuts and sleeves are snugly mated and securely fitted by proper flaring of the tubing. The line assembly should be clean and free of all foreign matter.,Basic Aircraft Systems Hydraulic System,RIGID FLUID LINE