Meticulously inspect all hydraulic hose and fittings at standard intervals to make sure airworthiness. Investigate any proof of fluid decline or leaks. Validate metallic tubes for leaks, unfastened anchorage, scratches, kinks, or other harm. Inspect fittings and connections for leakage, looseness, cracks, burrs, or other harm. Switch or restore defective components. Make specific the hoses usually do not chafe towards a person distinct an extra and therefore are appropriately secured and clamped.
a. Substitution of Metallic tube. When inspection displays hydraulic hose for being damaged or defective exchange the whole line or, if the damaged part is localized, a maintenance area is likely to be inserted. In replacing aircraft hose, generally use tubing of the exact same dimensions and product as the first line. Use the previous tubing as a template when bending the new tube, Except It is additionally drastically damaged, where circumstance a template could be established from smooth iron wire. Gentle aluminum tubing (1100, 3003, or 5052) beneath half-inch outdoors diameter might be bent by hand. For all other tubing use an acceptable hand or Vitality tube-bending Resource. Bend tubing really diligently to steer clear of excessive flattening, kinking, or wrinkling. A compact amount of flattening in bends is acceptable, but do not exceed 75 % of the initial outdoor diameter. Too much flattening will carry about fatigue failure in the hydraulic tube. When installing the substitution tubing line it up properly While using the mating component so that it is not compelled into alignment by tightening from the coupling nuts.
b. Hose couplings and Tube Connections. Numerous tube connections are established using flared tube finishes with standard connection fittings: AN-818 (MS 20818) nut and AN-819 (MS 20819) sleeve. In forming flares, reduce the tube finishes square, file clean, remove all burrs and sharp edges, and wholly clean up. The tubing is then flared utilizing the right 37-degree aviation flare forming Resource for the size of tubing and kind of fitting. A double flare is utilized on gentle aluminum tubing 3/8-inch outdoors diameter and beneath, and an individual flare on all other tubing. In creating the connections, use hydraulic fluid being a lubricant and after that tighten. Overtightening will harm the tube or fitting, which might bring about a failure. Beneath-tightening could carry about leakage which could consequence in a technique failure.
Warning: Mistaken usage of 45-degree automotive flare forming tools might consequence in poor tubing flare shape and angle resulting in misfit, panic and pressure, and possible procedure failure.
c. Repair service of plane hydraulic Metallic Tube Lines. Slight dents and scratches in tubing might be repaired. Scratches or nicks not deeper than ten % on the wall thickness in aluminum alloy tubing, that are not while in the heel of the bend, is likely to be fixed by burnishing with hand resources. Change traces with severe die marks, seams, or splits inside the tube. Any crack or deformity in the flare is unacceptable and produce about for rejection. A dent substantially a lot less than 20 % in the tube diameter is not objectionable Except if it’s during the heel of the bend. A severely-broken line genuinely really should get replaced nonetheless, it might be fixed by slicing out the damaged portion and inserting a tube section of the very same dimensions and material. Flare Every single ends on the undamaged and alternative tube sections and make the relationship by using regular unions, sleeves, and tube nuts.In case the damaged portion is fast ample, omit the insert tube and repair service by making use of 1 specific union and two sets of link hose fittings.
d.Substitute of Multipurpose Hose. When substitute of flexible hose is significant, use the very same kind, measurement, factor amount, and size of hose as the road to get replaced. Confirm TSO wants. If your substitute of the hose having a swaged-finish type fitting is important, acquire new hydraulic hose assemblies of the proper size and composition. Certain artificial oils demand from customers a specially compounded synthetic rubber hose, which is appropriate. Make reference to the plane manufacturer’s service information for the right aspect quantity for the alternative hose. If your fittings on Each and every and every finish are of the appropriate variety or sleeve form, a substitution might be fabricated. Just ahead of reducing new adaptable wire braided hose to the ideal measurement, tape the hose tightly with masking tape and lessen in the middle in the masking tape to guard versus fraying. The usage of a mandrel will protect versus slicing The within with the hose when inserting the fittings. Setup hose assemblies with no possessing twisting. A hose truly shouldn’t be stretched restricted involving two fittings as this tends to result in overstressing and eventual failure. The duration of hose seriously need to be adequate to supply about 5 to 8 % slack. Keep away from tight bends in flex lines as they could result in failure. Under no situation exceed the minimum bend radii.
(one) Teflon hose is used in loads of aircraft programs due to the reality it’s got remarkable characteristics for particular purposes. Teflon is compounded from tetrafluoroethylene resin which can be unaffected by fluids generally used in aircraft. It’s got an running a number of -65°File to 450 °File. For these motives, Teflon hose is used in hydraulic and engine lubricating programs exactly in which temperatures and pressures preclude the usage of rubber hose. Whilst Teflon hose has outstanding effectiveness features, In addition, it has peculiar qualities that desire further care in dealing with. It has a tendency to suppose a long term set when subjected to greater tension or temperature. Don’t endeavor to straighten a hose that has been in provider. Any too much bending or twisting may well carry about kinking or weakening of your tubing wall. Change any hose that displays indicators of leakage, abrasion, or kinking. Any hose suspected of kinking may very well be checked with a steel ball of suitable dimension.The ball won’t go Through When the hose is distorted beyond boundaries.
(two) In case the hose fittings are on the reusable kind, a substitute hose may be fabricated. When a hose assembly is taken out, the ends definitely need to be tied, so the preformed shape are going to be maintained.
(three) All functional hose installations definitely must be supported no less than each 24 inches. Nearer supports are favored. They seriously needs to be extremely very carefully routed and securely clamped to steer clear of abrasion, kinking, or abnormal flexing. Abnormal flexing may possibly carry about weakening with the hose or loosening for the fittings.