AC 43.13-1A Page 159 1972 Chapter 9. WINDSHIELDS, ENCLOSURES, AND EXITS Section 1. PLASTIC WINDSHIELDS AND ENCLOSURES
375. GENERAL. These repairs are applicable to plastic windshields, enclosures, and windows in nonpressurized airplanes. For pressurized airplanes replace or repair plastic elements in accordance with the manufacturer's recommendation.
a. Types of Plastics. Two types of plastics are commonly used in transparent enclosures of aircraft. These materials are known as acrylic plastics and polyester plastics.
new replacement or heat the whole panel and reform. When possible, cut and fit a new panel at ordinary room temperature.
b. In clamping or bolting plastic panels into their mountings, do not place the plastic under excessive compressive stress. It is easy to develop more than 1,000 pounds per square inch on the plastic by overtorquing a nut and bolt.
Tighten each nut to a firm fit, then back off one
376. REPLACEMENT PANELS. Use material equivalent to that originally used by the manufacturer of the aircraft for replacement panels.
There are many types of transparent plastics on the market. Their properties vary greatly, particularly in regard to expansion characteristics, brittleness under low temperatures, resistance to discoloration when exposed to sunlight, surface checking, etc. Information on these properties is in MIL-HDBK-17, Plastics for Flight Vehicles, Part II-Transparent Glazing Materials, available from the Government Printing Office. These properties have been considered by aircraft manufacturers in selecting materials to be used in their designs and the use of substitutes having different characteristics may result in subsequent difficulties.
377, INSTALLATION PROCEDURES. When installing a replacement panel, use the same mounting method employed by the manufacturer of the airplane. While the actual installation will vary from one type of aircraft to another, consider the following major principles when installing any replacement panel:
a. Never force a plastic panel out of shape to make it fit a frame. If a replacement panel does not fit easily into the mounting, obtain a
c. in bolt installations, use spacers, collars, shoulders, or stopnuts to prevent tightening the bolt excessively. Whenever such devices are used by the airplane manufacturer, retain them in the replacement installation. It is important that the original number of bolts, complete with washers, spacers, etc., be used.
When rivets are used, provide adequate spacers or other satisfactory means to prevent excessive tightening of the frame to the plastic.
d. Mount plastic panels between rubbed, cork, or other gasket material to make the installation waterproof, to reduce vibration, and to help to distribute compressive stresses on the plastic.
e. Plastics expand and contract considerably more than the metal channels in which they are mounted. Mount windshield panels to a sufficient depth in the channel to prevent it from falling out when the panel contracts at low temperatures or deforms under load. When the manufacturer's original design permits, mount panels to a minimum depth of 11/8 inch and with a clearance of 1/8 inch between the plastic and the bottom of the channel.
f. In installations involving bolts or rivets, make the holes through the plastic oversize 1/8 inch diameter and center so that the plastic will not Chap 9 Par 375
Page 160 AC 43.13-1A 1972
ALL THE STRAINS WHICH ORIGINALLY CAUSED CRACK ARE CONCENTRATED AT POINT 4)- TENDING TO EXTEND CRACK. THEREFORE DRILL A SMALL
HOLE AT END OF CRACK POINT (AI TO DISTRIBUTE STRAIN OVER WIDER AREA.
(AL
EACH CRACK OCCURRING AT ANY HOLE OR TEAR IS DRILLED IN SAME MANNER.
FIGURE 9.1.-Stop-drilling cracks.
bind or crack at the edge of the holes. The use of slotted holes is also recommended.
378. REPAIR OF PLASTICS. Replace extensively SUMAC E PATCH damaged transparent plastic rather than repair whenever possible since even a carefully DELLE patched part is not the equal of a new section either optically or structurally. At the first sign of crack development, drill a shall hole at the extreme ends of the cracks as shown in SURFACE PATCH FOR CRAC figure 9.1. This serves to localize the cracks and to prevent further splitting by distributing the strain over a large area. If the cracks are small, stopping them with drilled holes will usually suffice until replacement or more permanent repair can be made. The following repairs are permissible; however, they are not to be located in the pilot's line of vision during landing or normal fight. SURFACE PATCH FOR IRREGULAR R SHAPED DAMAGE
a. Surface Patch. If a surface patch is to be installed, trim away the damaged area and round all corners. Cut a piece of plastic of sufficient size to cover the damaged area and extend at least 8/4 Inch on each side of the crack or hole. Bevel the edges as shown in figure 9.2.
If the section to be repaired is curved, shape the patch to the same contour by heating it in SURFACE PATCH FOR ROUND HOLES an oil bath at a temperature of 248° to 802° F., or it may be heated on a hotplate until soft, FIGURE 9.2.-Surface patches Far 377 Chap 9
AC 43.13-1A Page 161 1972 Boiling water should not be used for heating.
Coat the patch evenly with plastic solvent adhesive and place immediately over the hole.
Maintain a uniform pressure of from 5 to 10 pounds per square inch on the patch for a minimum of 3 hours. Allow the patch to dry 24 to 36 hours before sanding or polishing is attempted.
b. Plug Potch. In using inserted patches to repair holes in plastic structures, trim the holes to a perfect circle or oval and bevel the edges slightly. Make the patch slightly thicker than the material being repaired and similarly bevel the edges. Install patches in accordance with figure 9.3. Heat the plug until soft and press into the hole without cement and allow to cool to make a perfect fit. Remove the plug, coat the edges with adhesive, and then reinsert in the hole. Maintain a firm light pressure until the
PATCHES PATCH SHOULD BE
THICKER cement has set, then sand or file the edges level with the surface; buff and polish.
379. CLEANING AND POLISHING TRANSPARENT PLASTIC. Plastics have many advantages over glass for aircraft use, but they lack the surface hardness of glass, and care must be exercised while servicing the aircraft to avoid scratching or otherwise damaging the surface.
a. Cleaning. Clean the plastic by washing with plenty of water and mild soap, using a clean, soft, grit-free cloth, sponge, or bare hands. Do not use gasoline, alcohol, benzene, acetone, carbon tetracholoride, fire extinguisher or deicing fluids, lacquer thinners, or window cleaning sprays because they will soften the plastic and cause crazing.
b. Plastics should not be rubbed with a dry cloth since this is likely to cause scratches, and also build up an electrostatic charge which attracts dust particles to the surface. If after removing dirt and grease no great amount of scratching is visible, finish the plastic with a good grade of commercial wax. Apply the wax in a thin even coat and bring to a high polish by rubbing lightly with a soft cloth.
c. Polishing. Do not attempt hand polishing PATCH AND HOLE PATCH TAPERED or buffing until the surface is clean. A soft, SHOULD BE TRIMMED ON SHARPER open-type cotton or flannel buffing wheel is sug- WITH TAPERED EDGES. MATERIAL. ANGLE THAN gested. Minor scratches may be removed by vigorously rubbing the affected area by hand, using a soft clean cloth dampened with a mix- HEAT EDGES OF DURING CEMENT- ture of turpentine and chalk, or by applying PATCH UNTIL SOFT AND FORCE IT IN NEED BE APPLIED ONLY ON TOP ING - PRESSURE the cleaner and polish with a soft, dry cloth. automobile cleanser with a damp cloth. Remove HOLE. HOLD SURFACE. TAPER Acrylic and cellulose acetate plastics are ther- IT IN PLACE ASSURES EQUAL moplastic. friction created by buffing or pol- UNTIL COOL AND HARD TO ASSURE PER- PRESSURE ON ALL SIDES, cient heat to soften the surface. This will ishing too long in one spot can generate suffi- FECT FIT. produce visual distortion and is to be guarded THEN REMOVE against.
PATCH FOR CEMENTING BATH. AFTER CEMENT HAS HARDENED - SAND OR 380. EMERGENCY EXITS. The following material is intended as a guide for the inspection and FILE EDGES LEVEL maintenance of aircraft emergency exit provi- WITH SURFACE. sions. Schedule inspections to coincide with all 100-hour/annual, progressive inspections or the maintenance procedures that have been ap- FIGURE 9.3.--Plug patch repair. proved by the Administrator. Before begin- Chap 9 Par 378
ning inspection or maintenance activities of any type, consult the appropriate manufacturer's service manual for information specifying the type of exit release mechanism used.
o. Inspection. Examine the emergency exits and all associated hardware closely for deformation, excessive wear, security of attachment, lubrication, and cleanness.
(1) Doors.
(a) Inspect the door structure and skin for wrinkles, cracks, alignment with the fuselage, deep scratches, dents, loose rivets, corrosion, or any other indication of structural irregularity.
(b) Examine rubber seals for cuts, tears, excessive wear, proper contact with the entire door frame, and general deterioration.
(c) Inspect bearings, hinges, hinge fairings, latches, springs, pins, rods, handles, and related parts for wear and general condition.
(d) Examine the door jamb, frame, and supporting structure for cracks, loose fasteners, condition of stops, and corrosion or
(e) Check the door for ease of operation and freedom of movement through its full range of travel.
(f) If a door warning light is provided, test it for proper operation and adjustment.
(g) Check the door locking mechanism for positive fit and at least the minimum lock pin engagement as specified in the applicable aircraft manual.
(2) Passenger Escape Hatches.
(a) Remove the escape hatch. Check for ease of removal and correct functioning of the release mechanism through all angles of pull likely to be encountered during emergency conditions.
CAUTION If applicable, position one man outside the aircraft to catch the hatch, thereby preventing it from falling and damaging the wing and/or hatch.
(b) Examine the escape hatch structure for cracka, dents, deep scratches, alignment, loose rivets and/or bolts, corrosion, or any other indication of structural irregularity.
(c) Inspect the rubber seals for excessive Par 380 AC 43.13-1A 1972 wear, deterioration, cuts, tears, and proper contact with the fuselage.
(d) Check the operating mechanisms for wear, cracks, and general condition; springs for proper tension, alignment, and security.
(e) If applicable, inspect external release mechanisms for wear, cracks, and proper operation. Check for presence and legibility of external placards and exit location markings.
(f) Examine the escape hatch opening jamb, frame, stops, and skin for cracks and other evidence of damage or failure.
(g) If an emergency escape rope is provided, check it for accessibility, attachment, freedom of operation, rot, broken strands, and general condition. Inspect the storage container or tube for sharp edges or moisture.
(3) Crew Compartment Sliding Windows.
(a) Inspect the window frame for cracks, dents, questionable scratches, loose rivets, corrosion, or any other indication of structural irregularity.
(b) Examine the extrusion seal for wear, general deterioration, and proper contact with the fuselage canopy.
(c) Check the window teleflex mechanism for loose bearings, wear, corrosion, and proper operation.
(d) Inspect the windows for cracks, scratches, nicks, crazing, fogging or moisture between panes, delaminations, hot spots or discoloration.
NOTE: Fogging or delaminations of windows other than windshields are generally not cause for replacement unless visibility is impaired. It is suggested the manufacturer be consulted on any question concerning win-
(1) Lubrication. Lubricate all moving parts of the exit latching mechanisms. The following practices will generally apply when specifc procedures are not available.
(a) Piano hinges and operating mechanism pivot points-oil lightly and wipe off excess. Use only oil that is compatible with the type of seal used on that specific aircraft. Do not allow the oil to contact fabrics or finished surfaces.
(b) Latch bolts and sliding surfaces- Chap o
AC 43.13-1A 1972 apply a light film from a graphite stick or latch lubricant (door ease).
(2) Seal Replacement. Information pertaining to special handling procedures for seals, gaskets, lubricants (dry or liquid), age limitations (shelf life), and types of adhesives may be found in the manufacturer's maintenance and overhaul manuals. Check the thickness of the seal or gasket for uniformity to prevent warping of the component, i.e., hatch or door. Exercise care when using adhesives to cement seals to the hatch frame or exit door as spillage or excessive amounts could cause the exit to bind.
NorE: Replace seals and gaskets with materials recommended by the manufacturer. Many times these materials have been changed due to service experience, therefore a check of manufacturers' service information should be made to ascertain that any replacement parts, materials, etc., are those currently recommended.
(3) Hatch/Window Replacement. Check replacement hatches or windows for proper size and fit to preclude opening problems. Improper loading of the aircraft or an accident may cause binding of the hatch/window if inadequate clearance exists.
(4) Emergency Exit Service Difficulties. Emergency exits that fail to open unless extreme force is exerted are usually caused by one of the following:
(a) Paint or primers on the mating surfaces of the exit which are not allowed to dry completely. As a result, the surfaces will stick to each other.
(b) Latches that bind or fail to work unless pulled straight out.
(c) Failure to lubricate mating or rubbing surfaces.
(d) Failure to operate exits after final assembly. The exits may perform satisfactorily before the airplane is painted, but the finishing process results in the application of solvents, cleaners, primers, and paint finishes that may tend to make the exit inoperable. Check the exit for ease of release after painting and finishing of an aircraft.
c. Operational Considerations.
Chap 9 Page 163
(1) Placards. Check to assure that all required placards and markings are installed (FAR 23.1557 (d) or 25.811). Make certain that curtains, drapes, clothes racks, etc. do not cover the placard or the exit operating handle.
When the normal exit identification signs are obstructed by compartmentation, galleys or other similar furnishings, use signs which contain the word "EXIT" and appropriate arrows to direct the attention of occupants to the exit locations.
(2) Precautions. Following any cabin interior modifications or configuration changes, check the accessability and operation of emergency exits by actual operation of the exit.
(a) Certain types of escape hatches have release handles which will not reinstall the lock pins into their locked position. If this type of release handle is pulled to any degree, either intentionally or inadvertently, it is necessary to ascertain that the locking pins are in position and safetied.
(b) Safety wire used to secure aircraft egress provisions should be of the type recommended by the manufacturer. Do not use stainless steel or other types of stiff wire. Acceptable substitutes would be either .011 copper or .020 aluminum soft safety wire.
(c) Some aircraft have inflatable door seals which assure a positive sealing capability during pressurization. Check these systems for proper operation in accordance with the manufacturer's maintenance instructions.
(d) Ascertain that seatbacks, tables, cabinets and other furnishings cannot interfere with the accessibility and opening of any exit either from inside or outside of the aircraft.
(3) Power Assist Devices. Some aircraft are presently equipped with powered systems to assist in door opening. It is imperative that the manufacturers' service instructions and manuals be reviewed before any maintenance is performed on such systems. These devices are usually hydraulically powered and, during an emergency condition, utilize a high-pressure bottle system as an alternate source (pneu- Par 380
Page 164 AC 43.13~1A 1972 matic or CO,). Future designs will quite possibly involve various combinations of hydraulic, electrical, or pneumatic units. Strict attention to all servicing procedures will be essential to assure proper functioning of the power-assist device when needed in an emergency.
381.-391. RESERVED.
Par 380 Chap 9
AC 43.13-1A CHG 1 Page 165 1975 Chapter 10. HYDRAULIC AND PNEUMATIC SYSTEMS Section 1. HYDRAULIC SYSTEMS
392. GENERAL. Maintain, service, and adjust connection fittings: AN-818 nut and AN-819 airplane hydraulic systems in uccordance with sleeve.
manufacturers' maintenance manuals and pertinent component maintenance manuals. Certain Minimum bend radii * general principles of maintenance and repair Wrench torque range measured at inside for tightening tube nuts of bend.
which apply are outhned below. Tube O.D. (inch pounds) Dimension in inches. * (Inches)
393. HYDRAULIC LINES AND FITTINGS. Carefully Alum. alley 1100-H14, Alum. alloy 1100-114, inspect all lines and fittings at regular intervals 5052-0 Steel 5052-0 Steel to insure airworthiness. Investigate any evidence of fluid loss or leaks. Check metal lines for 30-70 leaks, loose anchorages, scratches, kinks, or other 60-80 40-65 50-90 70-120 ½o 21⅛2 damage. Inspect fittings and connections for 75-125 00-150 1% leakage, looseness, cracks, burrs, or other damage. 150-250 155-250 1010 1¾e Replace or repair defective elements. 200-350 300-400 1¾ 300-500 430-575 13½ 2%6
a. Replacement of Metal Lines. When inspec- 500-700 550-750 1¾ 2% tion shows a line to be damaged or defective, 1 600-900 3½ replace the entire line or if the damaged section 1¾ 600-900 3¾ 4% is localized, a repair section may be inserted. In replacing lines, always use tubing of the same 1¾ 2 5 8 5¼ 8% size and material as the original line. Use the old tubing as a template in bending the new line, FIGURE 10.1.--Tube data.
unless it is too greatly damaged, in which case a template can be made from soft iron wire. In forming flares, cut the tube ends square, file Soft aluminum tubing (1100, 3003, or 5052) smooth, remove all burrs and sharp edges, and under ¼-inch outside diameter may be bent by thoroughly clean. The tubing is then flared hand. For all other tubing use an acceptable using the correct 37° aviation flare forming tool hand or power tube bending tool. Bend tubing for the size of tubing and type of fitting.
carefully to avoid excessive flattening, kinking, double flare is used on soft aluminum tubing or wrinkling. Minimum bend radii values are ⅛-inch outside diameter and under, and a single shown in figure 10.1. A small amount of flatten- flare on all other tubing. In making the connec ing in bends is ncceptable but do not exceed an tions, use hydraulic fluid as a lubricant and then amount such that the small diameter of the flat- tighten. Overtightening will damage the tube tened portion is less than 75 percent of the origi or fitting, which may cause a failure; undernal outside diameter. When installing the tightening may cause leakage which could result replacement tubing, line it up correctly with the in a system failure, mating part so that it is not forced into line by means of the coupling nuts. CAUTION Mistaken use of 45° automotive fare forming tools will
b. Tube Connections. Many tubing connections result in improper tubing fare shape and angle causing are made using flured tube ends, and standard misfit, stress and straln, and probable system failure.
Chap 10 Par 392
Page 166 AC 43.13-1A CHG 1 1975
c. Repair of Metal Tube Lines. Minor dents and scratches in tubing may be repaired. Scratches or nicks no 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 also unac.
ceptable and cause for rejection. A dent less than 20 percent of the tube diameter is not objectionable unless it is in the heel of a bend.
Dents may be removed by drawing a bullet of proper size through the tube by means of a length of cable. A severely damaged line should be replaced; however, it may be repaired by cutting out the damaged section and inserting a tube seotion of the same size and material. Flare both ends of the undamaged and replacement tube sections and make the connection 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 fittings.
d. Replacement of Flexible Lines. When replacement of a flexible line is necessary, use the same type, size, and length of hose as the line to be replaced. If the replacement of a hose with swaged-end-type fittings is necessary, obtain a new hose assembly of the correct size and composition. Certain synthetic oils require a specially compounded synthetic rubber hose which is compatible. Refer to the aircraft manufacturer's service information for correct part number for replacement hose. If the fittings on each end are of the collet type or sleeve type, a replacement may be fabricated as shown in figure 10.2. Typical aircraft hose specifications and their uses are shown in figure 10.3. Install hose assemblies without twisting. (See fgure
10.4.) Never stretch a hose tight between two fittings as this will result in overstressing and eventual failure. The length of hose should be sufficient to provide about 5 percent to 8 percent alack. Avoid tight bends in flex lines as they may result in failure. Never exceed the minimum bend radii as indicated in figure 10.5.
Teflon hose is used in many aircraft systems because of its superior qualities for certain applications. Teflon is compounded from tetrafluorothylene resin which is unaffected by fluids normally used in aircraft. It has an operating range of -65° F. to 450° F. For these reasons, Teflon is used in hydraulic and engine lubricating systems where temperatures and pressures preclude the use of rubber hose. Although Teflon hose has excellent performance qualities, it also has peculiar characteristics that require extra care in handling. It tends to assume a permanent set when exposed to high pressure or temperature. Do not attempt to straighten a hose that has been in service. Any excessive bending or twisting will 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. Figure 10.6 shows hose and ball sizes. The ball will not pass through if the hose is distorted beyond limits.
If the hose fittings are of the reusable type, a replacement hose may be fabricated as described in figure 10.2. When a hose assembly is removed the ends should be tied as shown in figure 10.7, so that its preformed shape will be maintained. Refer to figure 10.9 for minimum bend radii of Teflon hose.
All flexible hose installations should be supported at least every 24 inches. Closer supports are preferred. They should be carefully routed and securely clamped to avoid abrasion, kinking, or excessive flexing. Excessive flexing may cause weakening of the hose or loosening at the fittings.
e. O-Ring Seals. A thorough understanding of O-ring seal applications is necessary to determine when replacement must be made. The simplest application is where the O-ring merely serves as a gasket when it is compressed within a recessed area by applying pressure with a packing nut or screw cap.
Leakage is not normally acceptable in this type of installation. In other installations the O- ring seals depend primarily upon their resiliency to accomplish their sealing action. When moving parts are involved, minor seepage may be normal and acceptable. A moist surface found on moving parts of hydraulic units is an indication the seal is being properly lubricated.
In pneumatic systems, seal lubrication is provided by the installation of a grease-impreg- Par 393 * U.S. GOVERNMENT PRINTING OFFICE: 1975-631-513/928 3-1 Chap 10
AC 43.13-1A Page 167 1972
LENE ST
COYER WIN ENE
TO WHE DAG
TWIST OFF
COVER WITH PLIERS
1. Place hose in vise and cut to 2. Locate length of hose to be cut desired length using fine tooth off and slit cover with knife to wire hacksaw or cut off wheel. brald. After slitting cover, twist off with pair of pliers. (see nole below)
3. Place hose in vise and screw 4. "Lubricate inside of hose and socket on hose counterclockwise. nipple threads liberally.
NOTE:
Hose assemblies fabricated per MIL-H-8790 must have exposed wire braid coated with a special sealant.
NOTE:
Step 2 applies to high pressure hose only.
Screw nipple into socket using wrench on hex of nipple and leave .005 inches to .031 inches clearance between nipple hex and socket.
*CAUTION:
Do not use any petroleum product with hose designed for synthetic fluids "SKYDROL".
For a lubricant during assembly use a vegetable soap liquid.
DISASSEMBLE IN REVERSE ORDER FIGURE 10.2.-Hose assembly instructions.
Chap 10 Par 393
Page 168 AC 43.13-1A 1972
SINGLE WIRE BRAID FABRIC COVERED NUSE HOSE HOSE RECOMM. MIN. MAX. MIN.
MIL SIZE SIZE SIZE OPER. BURST PROOF BEND PART NO. O.D. I.D. O.D. PRESS. PRESS. PRESS. RADIUS MIL-H-B794- 3-1 45 3,000 12,000 6,000 3.00 MIL-H-8794- 4-1 -52 3,000 12,000 6,000 3.00 MIL-H-8794. 5-1 -56 3,000 10,000 5.000 3.38 MAIL-H-8794 6-1 -07 2,000 9,000 4,500 4.00 MIL-H-B794. 8-1 2,000 8,000 4,000 4.63 MIL-H-8794-10-6 -92 1,750 7,000 3,500 5.50 MIL-H-8794-12-L 1.08 1,500 6,000 3,000 6.50 MIL-H-8794-16-L 1.23 800 3,200 1,600 7.38 MIL-H-8794-20-1 1¼ 1.50 600 2,500 1,250 9.00 MIL-H-8794-242 1% 175 500 2,000 1,000 11.00 MIL-H-8794-32-L 1'Хo 2.22 350 1,400 700 13.25 MIL-M-0794-40-1 2% 2.88 200 1,000 300 24.00 MIL-M-8794-48-L 3.56 200 800 300 33.00 Construction: Seamless syn- Uses:
thetic rubber inner tube rein- Hose is approved for use in forced with one fiber braid, one braid of high tensile aircraft hydraulic, pneumatic, coolant, fuel and oil systems.
steel wire and covered with an oil resistant rubber im- Operating pregnated fiber braid. Temperatures:
Identification: Hose is iden- tified by specification num- Sizes -3 thru - 12: Minus 65°F. to plus 250°F.
ber, size number, quarter Sizes - 16 thru - 48: Minus year and year, hose manu- 40°F. 1o plus 275°F.
facturer's Identification. NOTE, Maximum temperatures and pres.
sures should not be used simullaneously.
MULTIPLE WIRE BRAID RUBBER COVERED TUBE HOSE HOSE ВЕСОМИ. NIM. MIM. Лік.
SIZE SIZE SIZE OFER BURST PROOF SEND PART NO. O.D. I.D. O.D. PRESS. PRESS. PRESS BADIUS MIL-H-9788. 4-1 ,63 3,000 16,000 8,000 3.00 MIL-H-B788-51 70 3,000 14,000 7,000 3.36 MIL-H-B788- 6-L 3,000 14,000 7,000 3.00 MIL-H-8788- S-L ,86 3,000 14,000 7,000 5.75 MIL-H-8788-10-1 1.03 3,000 12,000 6,000 6.50 MIL-H-8788-12-L ¼ 1.22 3,000 12,000 6,000 775 MIL-H-8788-16-1 1.50 3,000 10,000 5,000 9.63 Hose Constructions Seamless synthetic rubber inner tube reinforced with one fabric braid, two or more steel wire braids, and covered with a synthetic rubber cover (for gas applications request perforated cover).
Identification: Hose is identified by specification number, size number, quarter year and year, hose manufacturer's Identification.
Usos: High pressure hydraulic, pneumatic, coolant, fuel and oil.
Operating Temperatures:
Minus 65°F. to plus 200°F.
FIGURE 10.3.-Aircraft hose specificationa.
Par 393 Chap 10
AC 43.13-1A Page 169 1972
RIGHT WAY WRONG WAY Do not bend or twist the hose as 1001 319 illustrated.
Allow enough slack in the hose line to provide for changes in length when pressure is applied.
The hose will change in length from +296 to -19%.
Metal and fittings cannot be considered as part of the flexible portion of the assembly.
The use of elbows and adapters will assure easier installation and in many installations will remove the strain from the hose line and greatly increase service life.
At all times keep the minimum bend radil of the hose as large (pee as possible to avoid tube collapsing.
FIGURE 10.4.-Proper hose installations.
Chap 10 Par 393
Page 170 AC 43.13-1A 1972 INSIDE BEND RADII V.S. OPERATING PRESSURE MIL-H-8794 HOSE WITH NO FLEXING 10 = • 200 400 600 800 1000 1500 2000 2500 3000 OPERATING PRESSURE -POUNDS/SO. IN. (-3 TO -24 INCLUSIVE) MINIMUM BEND RADII FOR - 32, - 40, AND - 48 AT ALL PRESSURES ARE AS FOLLOWS: -32 13.25" MIL-M-8788 HOSE WITH -40 24ª NO FLEXING -48 33" DASK NO. SEND RADHI
1.3 3.000
3.375
1.2 5.000
5.750 10 8.500 12 7.750 20 40 60 80 100 120 140 160 180 16 9.625
TOTAL FLEXING RANGE OF INSTALLED HOSE (DEGREES) MINIMUM BEND RADIUS OF HOSE UNDER FLEXING CONDITIONS = IN" × NO FLEXING BEND RADIUS OF EITHER MIL-H-8794 OR MIL-H-8788 HOSE.
EXAMPLE: FOR MIL-H-8794 HOSE SIZESIZE AT T5ОD PSI AND HAVING A FLEXING RANGE OF 60 MINIMUM BEND RADIUS = 1.16 × 6.5 = 7½ INCHES (MEASURED AT INSIDE OF BEND).
MINIMUM BEND RADI MEASURED AT INSIDE OF BEND DIMENSIONS IN INCHES.
FIGURE 10.5.-Minimum bend radil.
Par 393 Chap 10