Carefully inspect all hydraulic hose and fittings at regular intervals to make sure airworthiness. Investigate any proof fluid loss or leaks. Check metal tubes for leaks, loose anchorage, scratches, kinks, or other damage. Inspect fittings and connections for leakage, looseness, cracks, burrs, or other damage. Replace or repair defective elements. Make certain the hoses don't chafe against one another and are correctly secured and clamped.
a. Replacement of Metal tube. When inspection shows hydraulic hose to be damaged or defective replace the whole line or, if the damaged section is localized, a restoration section may be inserted. In replacing aircraft hose, always use tubing of the exact same size and material as the initial line. Use the old tubing as a template when bending the newest tube, unless it's too greatly damaged, by which case a template could be created from soft iron wire. Soft aluminum tubing (1100, 3003, or 5052) under half-inch outside diameter may be bent by hand. For all the tubing use an acceptable hand or power tube-bending tool. Bend tubing carefully in order to avoid excessive flattening, kinking, or wrinkling. A little bit of flattening in bends is acceptable, but don't exceed 75 percent of the initial outside diameter. Excessive flattening will cause fatigue failure of the hydraulic tube. When installing the replacement tubing line it down correctly with the mating part so that it isn't forced into alignment by tightening of the coupling nuts.
b. Hose couplings and Tube Connections. Many tube connections are created using flared tube ends with
standard connection fittings: AN-818 (MS 20818) nut and AN-819 (MS 20819) sleeve. In forming flares, slice the tube ends square, file smooth, remove all burrs and sharp edges, and thoroughly clean. The tubing is then flared using the correct 37-degree aviation flare forming tool for the size of tubing and kind of fitting. A dual flare is used on soft aluminum tubing 3/8-inch outside diameter and under, and a single flare on all the tubing. In making the connections, use hydraulic fluid as a lubricant and then tighten. Overtightening will damage the tube or fitting, which can create a failure. Under-tightening may cause leakage which could create a system failure. TorcStark
CAUTION: Mistaken utilization of 45-degree automotive flare forming tools may lead to improper tubing flare shape and angle; causing misfit, stress and strain, and probable system failure.
c. Repair of aircraft hydraulic Metal Tube Lines. Minor dents and scratches in tubing may be repaired. Scratches or nicks not deeper than 10 percent of the wall thickness in aluminum alloy tubing, that are not in the heel of a bend, may be repaired by burnishing with hand tools. Replace lines with severe die marks, seams, or splits in the tube. Any crack or deformity in a flare is unacceptable and reason for rejection. A dent less than 20 percent of the tube diameter isn't objectionable unless it's in the heel of a bend. A severely-damaged line ought to be replaced; however, it may be repaired by reducing the damaged section and inserting a pipe element of the exact same size and material. Flare both ends of the undamaged and replacement tube sections and make the bond by using standard unions, sleeves, and tube nuts.If the damaged portion is short enough, omit the insert tube and repair by using one union and two sets of connection hose fittings.
d.Replacement of Flexible Hose. When replacement of flexible hose is important, use the same type, size, part number, and length of hose since the line to be replaced. Check TSO requirements. If the replacement of a hose with a swaged-end type fitting is important, obtain new hydraulic hose assemblies of the correct size and composition. Certain synthetic oils require a specially compounded synthetic rubber hose, which can be compatible. Refer to the aircraft manufacturer's service information for the correct part number for the replacement hose. If the fittings on each end are of the correct type or sleeve type, an alternative may be fabricated. Before cutting new flexible wire braided hose to the appropriate size, tape the hose tightly with masking tape and cut in the middle of the masking tape to prevent fraying. The use of a mandrel will prevent cutting the inside of the hose when inserting the fittings. Install hose assemblies without twisting. A line shouldn't be stretched tight between two fittings as this will result in overstressing and eventual failure. Along hose ought to be sufficient to offer about 5 to 8 percent slack. Avoid tight bends in flex lines as they might lead to failure. Never exceed the minimum bend radii.
(1) Teflon hose is found in many aircraft systems because it's superior qualities for many applications. Teflon is compounded from tetrafluoroethylene resin which can be unaffected by fluids normally found in aircraft. It has an operating range of -65°F to 450 °F. For these reasons, Teflon hose is found in hydraulic and engine lubricating systems where temperatures and pressures preclude the usage of rubber hose. Although Teflon hose has excellent performance qualities, it also offers peculiar characteristics that want extra care in handling. It will assume a lasting set when subjected to high pressure or temperature. Don't attempt to straighten a hose that has been doing service. Any excessive bending or twisting may cause kinking or weakening of the tubing wall. Replace any hose that shows signs of leakage, abrasion, or kinking. Any hose suspected of kinking may be checked with a steel ball of proper size.The ball will not move across if the hose is distorted beyond limits.
(2) If the hose fittings are of the reusable type, an alternative hose may be fabricated. When a hose assembly is removed, the ends ought to be tied, so the preformed shape is likely to be maintained.bolting tools
(3) All flexible hose installations ought to be supported at the least every 24 inches. Closer supports are preferred. They must be carefully routed and securely clamped in order to avoid abrasion, kinking, or excessive flexing. Excessive flexing may cause weakening of the hose or loosening at the fittings.
Troubleshooting Hydraulic Machines
Hydraulic machines are found in varied industrial activities today. No doubt manufacturers of hydraulic machinery are taking keen curiosity about producing the best machines, which are well designed, well manufactured and can provide a reliable performance for many years. Any user who uses hydraulic equipments would always like to truly have a trouble free system. But to truly have a hydraulic machine without giving you any trouble sounds too good to be true. Even if the oil or filter is changed regularly, or even if the preventive maintenance program is followed, the device will probably stop sooner or later of time. This becomes all the more dangerous when it happens in the midst of a generation process.
What can you do under this circumstance? It is way better to be ready for such a situation so the work isn't stopped for an extended amount of time. This is exactly what is referred as troubleshooting your hydraulic machine. Presenting below some easy approaches to hydraulic troubleshooting.
To start with, learn hydraulics, find out how they work since this is the better way you are able to handle a problem. Understand how all the equipment work, how the device handles pressure, flow and direction, how they are connected to each other. Study the manufacturer's catalog. Gather the maximum amount of details about breakdowns, lists of components, pressure settings, testing points, how many actuators, pumps, valves are found in the system.
Don't await the full time when the device is wholly not working. In reality some precautions can be studied even though the device is in an operating condition. All hydraulic machines operators must follow a
When actually the hydraulic machine stops working, do the following:
- Discover under what circumstances or what caused the device to are amiss?
- Was it at the beginning of the cycle?
- Speak with the device operator.
- Try to have the maximum amount of information as possible.
- Check the hydraulic schematics. Discover the road from the pump to the actuator. Which actuator or valve was working when the device stopped?
- Discover whether you will find any problems in some components like pumps, some directional valves, some flow controls, relief valves.
- Perform the flow and pressure test adding one more element just like the relief valve after the pump, and etc until you get to the cylinder.
Once yo gather information, its time and energy to act. In short, hydraulic trouble shooting is not just a quite simple task, but with proper familiarity with hydraulics, with full machine information and equipment, troubleshooting becomes easier and faster.u
All About Hydraulic Check Valves
Hydraulic check valves are the absolute most popular valves that allow fluid to flow in a single direction in a hydraulic system and prevent reversal of liquid flow. That is why the name the "check valve" ;.Put simply, this revolutionary product is installed in a tube so the water does not flow backwards inside the pipe. There is a mechanism inside the pipe which moves according to the flow of the water towards the valve, and when required, the mechanism plugs up the valve opening so that there is no flow of water backwards.
In a hydraulic check valve, you will find two openings. The inlet through which the hydraulic fluid enters and an outlet through which the fluid goes out. A good thing is which they operate automatically. They work in relation with hydraulic pumps, motors and cylinders. The valves control the flow and pressure of the fluid so that there is proper functioning of the equipment.
There are different designs obtainable in hydraulic valves like ball, plunger, swinging disc, and poppet. Depending on the application area, the size and shape varies. These check valves are found in industrial applications that want hydraulic pumps, like in automotive braking systems, vehicles, construction tools, including city water and sewer systems. They're found in systems the place where a backup of fluid could cause problems on a sizable scale.
Hydraulic valves are useful for different reasons such as follows:
- The vital role they play is which they prevent flooding if you have extreme back flow of water running through the pipes.
- They prevent the damage of the device from water flowing the wrong direction.
- When the device is deterred, the valve helps in preventing the fluid from flowing back in the wrong direction. Inturn, they save power and also protect the pipes from water damage.
- They allow liquid flow in a single direction.
- They control fluid pressure.
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