Par 9-42 Page 9-43
(b) Mark the center line on the side of the patch that is to be attached to the raft.
Mark cross lines on each end of the patch 1-1/2 inches from the ends. When the patch is applied to the injury on the inside, the longitudinal edges of the injury will coincide with the center line, and cross lines on the ends of the patch will coincide with the ends of the injury.
(c) To ensure that the inside surface of the raft is properly powdered in the area of repair, pass a small handful of talc through the opening in the raft and place it approximately 12 inches from the injury. This should be accomplished before the inside area is cemented, exercising care to prevent distribution of the talc prior to completion of the repair.
FIGURE 9-14. REPAIR DIMENSIONS
(d) U sing cleaning solvent, cleanse an area on the inside surface of the fabric slightly larger than the patch to be applied. Ensure that the repaired area is thoroughly dry, both inside and outside; apply two coats of extra-light cement, two coats of light cement, and three coats of heavy cement (or six additional coats of light cement in lieu of the heavy cement) to the cleansed area, allowing each coat to dry thoroughly before applying successive coats.
NOTE: Since it is impossible for the repairman to visually observe the cementing that is being accomplished on the inside of the raft, exercise care to ensure that each coat of cement completely covers the area to be repaired.
(e) The inside patch should be cemented simultaneously with the application of cement to the inside of the raft. Apply the same number of coats as directed in subparagraph 9-42c(2)(d) to the side of the patch that is applied to the injured fabric of the raft.
Ensure that each coat is thoroughly dry before applying the next coat.
(f) To aid in adhesion, prior to applying the patch, the inside area to be repaired and cemented surface of the patch should be cleaned with a cloth moistened with rubber solvent. The cement will then become tacky.
Par 9-42 Page 9-44
(g) Apply the patch. Fold the patch lengthwise in the shape of the letter “U” and insert the patch between the torn edges of the injury on the life rafts. Position the patch so that the fabric at the end of the tear will coincide with a cross line and the center line on the patch follows one edge of the torn fabric. Attach one edge of the torn fabric along the center line on the patch.
(h) Inspect the repair for wrinkles. Working from the attached edge of the fabric to the edge of the patch, remove the wrinkles with a stitcher. Lay the opposite edge of the torn fabric on the patch so that it butts the edge of the torn fabric that has already been applied to the patch. Remove the wrinkles. Thoroughly roll the patch with a 2-inch rubber roller.
NOTE: The surface under the patch should be as smooth as possible so that the torn edge of the fabric may be attached to the patch instead of attempting to attach the patch to the fabric.
(i) Scatter the handful of talc that was placed inside the tube by grasping the sides of the flotation tube and pulling them apart.
(j) Prepare and attach the outside patch as outlined in “Outside Patches,” subparagraphs 9-42c(1)(a)–(e).
(k) Allow to cure for at least 60 hours before performing leak tests and storing.
(3) Seams and Tapes.
(a) Remove all old or dead cement from the area that will require recementing.
Dampen the repair area with a solvent-moistened cloth; then roll or rub off the old cement.
(b) Apply cement to the surface as outlined in “Outside Patches,” subparagraphs 9-42c(1)(a)–(e).
(c) Roll thoroughly with a roller to ensure that all air pockets are removed and a firm bond is secured.
(d) Allow to dry and apply talc over the seam as previously outlined.
(e) Allow to cure for at least 60 hours before performing leak tests and storing.
9-43. LIFE PRESERVERS. Inflatable life preservers are subject to general deterioration due to aging. Experience has indicated that such equipment may be in need of replacement at the end of 5 years due to porosity of the rubber-coated material. Wear of such equipment is accelerated when stowed on board aircraft because of vibration which causes chafing of the rubberized fabric. This ultimately results in localized leakage. Leakage is also likely to occur where the fabric is folded because sharp corners are formed. When these corners are in contact with the carrying cases, or with adjacent parts of the rubberized fabric, they tend to wear through due to vibration. Life preservers should be inspected in accordance with the manufacturer’s specification, unless climate, storage, or operational conditions indicate the need for more frequent inspections (refer to TSO-C13g).
Par 9-44 Page 9-45
9-44. LIFE PRESERVER INSPECTION. Life preservers should be inspected at 12-month intervals for cuts, tears, or other damage to the rubberized material. Check the mouth valves and tubing for leakage, corrosion, and deterioration. Remove the CO2 cylinder and check the discharge mechanism by operating the lever to ascertain that the pin operates freely. Check the gaskets and valve cores of the cylinder container and the pull cord for deterioration. If no defects are found, inflate the preserver with air to a 2-psi pressure and allow to stand for 12 hours. If the preserver still has adequate rigidity at the end of that time, deflate and fit with CO2 cylinders having weights not less than that indicated on them by the manufacturer. All cylinders made in accordance with joint Army/Navy Specification MIL-C-601D are so stamped and have a minimum permissible weight stamped on them. The use of such CO2 cylinders is recommended.
Having fitted the preserver with an adequately charged cylinder, mark the preserver to indicate the date of inspection and patch it to the container. It is recommended that the aforementioned procedure be repeated every 12-month period, utilizing the CO2 cartridge for inflation. CO2 permeates the rubberized fabric at a faster rate than air and will indicate if the porosity of the material is excessive. The following checks and inspections should be completed:
a. Check for abrasions, chafing, and soiling across folded cell areas and around metal parts. Condemn the life preserver when unsuitable conditions are found.
b. Check for separation of cell fabric and loose attachments along the edges of patches and sealing tapes. Repair if practicable.
c. Check for deterioration in areas where oil and grease are noted. Condemn deteriorated cells. If deterioration is not noted, clean the areas with mild soap and water and rinse with clear water.
d. Inspect the snaps and/or buckles to ensure proper operation.
e. Inspect the instruction panel for readability.
f. Inspect all stitching for gaps, pulls, and tears.
g. Visually inspect the cell containers for snags, cuts, loose stitching, and oil and grease spots. Repair or replace as necessary.
h. Inspect the hardware for rusted or broken parts and cotter pins for damage. Ensure that pins are smooth and free of burrs.
i. Check the inflator discharge lever for proper operation. Move the inflator discharge lever slowly through a normal cycle of operation to ensure freedom of operation and to make certain that the piercing pin has sufficient movement to discharge the CO2 cylinder. The point of the pin should move past the surface of the gasket in the inflator. In the unoperated position, the end point should be slightly below the gasket surface.
j. Check the installation of the inflator stem gaskets and check the stem caps for tightness. Ensure that the inflator is centered on the stem.
k. Check rescue light. Inspect and test.
Par 9-44 Page 9-46
(1) Replace the battery if it shows any signs of encrustation.
(2) Inspect for proper installation and physical condition of the lamp, wire, and battery.
(3) Check the light assembly for proper operation and water insulation and flotation.
(4) Pull the sealing plug (where applicable) from the battery. Let water flow through the open ports. Make sure the battery is activated and power is supplied to the light.
(5) Fill out the inspection record and serviceable parts tag. Attach to the vest.
l. Deflate the life preserver and repack in container and secure.
m. The accessories listed below will be required for all life preservers:
(1) One Recognition Light: Remove when returning to serviceable or reparable storage.
Remove for replacement of defective light, repair, or salvage of preserver.
(2) One Recognition Light Battery: Remove when returning to serviceable or reparable storage.
n. Record the inspection data on data cards.
o. Life preserver inspected and found seaworthy. Include the inspector’s signature.
p. Inspection record. Upon completion of 12-month inspection and tests, each flotation cell will be marked to indicate the date the inspection was accomplished. The inspection stencil will consist of 1/8-inch letters and numerals and will be applied to the patches on the cells (example: 4/3/97). To facilitate determination of the next 12-month inspection period, enter the date it is due in the blank beside the word inspect on the inspection data card provided in the inspection data pocket on the cell container. Repack, close, and seal the container.
9-45. REPAIR OF LIFE PRESERVERS. Leaks may be disclosed by immersion in soapy water. Repair leaks by the use of patches in accordance with the recommendations of the manufacturer. Clean corroded metal parts and replace missing or weakened lanyards. Life preservers which do not retain sufficient rigidity after the 12-hour period, because of general deterioration and porosity of the fabric, are beyond economical repair and should be replaced.
9-46. MISCELLANEOUS EQUIPMENT.
a. Parachutes. With reasonable care, parachutes can remain in service indefinitely. They should not be carelessly tossed about, left in aircraft to become wet, or left where someone may tamper with them. They should not be placed where they may fall on oily floors or be subject to acid fumes from adjacent battery chargers.
(1) When repacking is scheduled, to comply with the 180-day requirement in 14 CFR part 105, § 105.43, a careful inspection of the parachute shall be made by a qualified parachute technician (rigger). If repairs or replacements of parts are necessary to maintain the airworthiness
Par 9-46 Page 9-47 of the parachute assembly, such work must be done by the original parachute manufacturer or by a qualified parachute rigger, certificated in accordance with 14 CFR part 65.
(2) The lead seal should be inspected periodically to ensure the thread has not been broken. If broken, broken and retied, or appears to have been tampered with, the parachute must be repacked by a properly certified rigger.
b. Safety Belts shall be of an approved type. All seat belts and restraint systems must conform to standards established by the FAA. These standards are contained in TSO-C22g for seat belts and TSO-C114 for restraint systems.
(1) Safety belts eligible for installation in aircraft must be identified by the proper TSO markings on the belt. Each safety belt must be equipped with an approved metal to metal latching device. Airworthy type-certificated safety belts currently in aircraft may be removed for cleaning and reinstalled. However, when a TSO safety belt is found unairworthy, replacement with a new TSO-approved belt or harness is required.
(2) The webbing of safety belts, even when mildew-proofed, is subject to deterioration due to constant use, cleaning, and the effects of aging. Fraying of belts is an indication of wear, and such belts are likely to be unairworthy because they can no longer hold the minimum required tensile load.
(3) Safety belts shall be repaired in accordance with specifications approved by the responsible FAA Aircraft Certification Service office.
9-47. OXYGEN SYSTEMS. The following instructions are to serve as a guide for the inspection and maintenance of aircraft oxygen systems. The information is applicable to both portable and permanently installed equipment.
a. Aircraft Gaseous Oxygen Systems. The oxygen in gaseous systems is supplied from one or more high- or low-pressure oxygen cylinders. Since the oxygen is compressed within the cylinder, the amount of pressure indicated on the system gauge bears a direct relationship to the amount of oxygen contained in the cylinder. The pressure-indicating line connection is normally located between the cylinder and a pressure-reducing valve.
NOTE: Some of the gaseous oxygen systems do not use pressure-reducing valves. The high pressure is reduced to a useable pressure by a regulator.
This regulator is located between the high- and low-pressure system.
CAUTION: Oxygen-rich environments are dangerous.
b. Portable Oxygen Systems. The three basic types of portable oxygen systems are:
demand, pressure demand, and continuous flow. The components of these systems are identical to those of a permanent installation with the exception that some parts are miniaturized as necessary. This is done in order that they may be contained in a case or strapped around a person’s shoulder. It is for this portability reason that special attention be given to assuring that any storage or security provision for portable oxygen equipment in the aircraft is adequate, in good condition, and accessible to the user.
Par 9-47 Page 9-48 NOTE: Check portable equipment, including its security provisions, frequently, since it is more susceptible to personnel abuse than a permanently installed system.
9-48. INSPECTION. Hands, clothing, and tools must be free of oil, grease, and dirt when working with oxygen equipment. Traces of these organic materials near compressed oxygen may result in spontaneous combustion, explosions, and/or fire.
a. Oxygen Tanks and Cylinders. Inspect the entire exterior surface of the cylinder for indication of abuse, dents, bulges, and strap chafing.
(1) Examine the neck of cylinder for cracks, distortion, or damaged threads.
(2) Check the cylinder to determine if the markings are legible.
(3) Check the date of the last hydrostatic test. If the periodic retest date is past, do not return the cylinder to service until the test has been accomplished.
(4) Inspect the cylinder mounting bracket, bracket hold-down bolts, and cylinder-holding straps for cracks, deformation, cleanliness, and security of attachment.
(5) In the immediate area where the cylinder is stored or secured, check for evidence of any types of interference, chafing, deformation, or deterioration.
b. Lines and Fittings.
(1) Inspect oxygen lines for chafing, corrosion, flat spots, and irregularities, i.e., sharp bends, kinks, and inadequate security.
(2) Check fittings for corrosion around the threaded area where lines are joined.
Pressurize the system and check for leaks. (See paragraph 9-49b(2)(d).)
CAUTION: In pressurizing the system, actuate the valve slowly to avoid surging which could rupture the line.
c. Regulators, Valves, and Gauges.
(1) Examine all parts for cracks, nicks, damaged threads, or other apparent damage.
(2) Actuate the regulator controls and the valve to check for ease of operation.
(3) Determine if the gauge is functioning properly by observing the pressure buildup and the return to zero when the system oxygen is bled off.
d. Masks and Hoses.
(1) Check the oxygen mask for fabric cracks and rough face seals. If the mask is a full-face model, inspect the glass or plastic for cleanliness and state of repair.
Par 9-48 Page 9-49
(2) When appropriate, with due regard to hygienic considerations, the sealing qualities of an oxygen mask may be tested by placing a thumb over the connection at the end of the mask tube and inhaling very lightly. Remove the thumb from the disconnect after each continuous inhalation. If there is no leakage, the mask will adhere tightly to the face during inhalation, and definite resistance to inhalation will be noticeable.
(3) Flex the mask hose gently over its entirety and check for evidence of deterioration or dirt.
(4) Examine the mask and hose storage compartment for cleanliness and general condition.
(5) If the mask and hose storage compartment is provided with a cover or release mechanism, thoroughly check the operation of the mechanism.
9-49. MAINTENANCE.
a. Oxygen Tanks, Cylinders, and Hold-Down Brackets.
(1) Remove from service any cylinders that show signs of abuse, dents, bulges, cracks, distortion, damaged thread, or defects which might render them unsafe. Typical examples of oxygen cylinder damage are shown in Figure 9-15.
NOTE: Cylinders having greater weight or size will require strengthened cylinder-mounting brackets and a reevaluation to determine that the larger or heavier cylinder will not interfere with adjacent systems, components, or structural members, and that the strength of attaching structure is adequate and any additional weight will be computed into the aircraft’s weight and balance report.
(2) When replacing an oxygen cylinder, be certain that the replacement cylinder is of the same size and weight as the one removed.
FIGURE 9-15. OXYGEN CYLINDER DAMAGE
(3) R eplace or repair any cylinder mounting brackets that show signs of wear. Visible cracks may be welded in accordance with manufacturer’s standards. Replace the cylinder straps
Par 9-49 Page 9-50 or clamps that show wear or abuse. For typical mounting bracket cracks and failure, see Figure 9-16.
FIGURE 9-16. CYLINDER BRACKETS AND CLAMPS
b. Li nes and Fittings.
(1) Replace any oxygen line that is chafed, rusted, corroded, dented, cracked, or kinked.
(2) Clean oxygen system fittings showing signs of rusting or corrosion in the threaded area. To accomplish this, use a cleaner recommended by manufacturers of oxygen equipment.
Replace lines and fittings that cannot be cleaned.
(a) The high-pressure lines which are located between the oxygen bottle (outside the oxygen service filler) and the regulator are normally fabricated from stainless steel or thick-wall, seamless copper alloy tubing. The fittings on high-pressure lines are normally silver brazed.
NOTE: Use silver alloys free of cadmium when silver brazing. The use of silver brazing alloys which contain cadmium, will emit a poisonous gas when heated to a molten state. This gas is extremely hazardous to health if inhaled.
(b) The low-pressure lines extend from the pressure regulator to each passenger and crew oxygen outlet. These lines are fabricated from seamless aluminum alloy, copper, or flexible hose. Normally, flare- or flange-type connections are used.
CAUTION: Do not allow oil, grease, flammable solvent, or other combustibles such as lint or dust to come in contact with threads or any parts that will be exposed to pressurized oxygen.
(c) It is advisable to purge the oxygen system any time work has been accomplished on any of the lines and fittings. Use dry nitrogen or dry air for purging the system. All open lines should be capped immediately after purging.
(d) When oxygen is being lost from a system through leakage, a sequence of steps may be necessary to locate the opening. Leakage may often be detected by listening for the
Par 9-49 Page 9-51 distinct hissing sound of escaping gas. If this check proves negative, it will be necessary to soap-test all lines and connections with a castile soap and water solution or specially compounded leak-test material. Make the solution thick enough to adhere to the contours of the fittings. At the completion of the leakage test, remove all traces of the soap and water.
CAUTION: Do not attempt to tighten any connections while the system is charged.
c. Regulators, Valves, and Gauges. Line maintenance of oxygen regulators, valves, and gauges does not include major repair. These components are precision made and their repair usually requires the attention of a repair station or the manufacturer. Care must be taken when reinstalling these components to ascertain if the threaded area is free of nicks, burrs, and contaminants that would prevent the connections from sealing properly.
CAUTION: Do not use petroleum lubricants on these components.
d. Masks and Hoses.
(1) Troubleshooting. If a mask assembly is defective (leaks, does not allow breathing, or contains a defective microphone), it is advisable to return the mask assembly to the manufacturer or a repair station.
(2) Maintenance Practice and Cleaning.
(a) Clean and disinfect the mask assemblies after use, as appropriate.
NOTE: Use care to avoid damaging the microphone assembly while cleaning and sterilizing.
(b) Wash the mask with a mild soap solution and rinse it with clear water.
(c) To sterilize, swab the mask thoroughly with a gauze or sponge soaked in a water-merthiolate solution. This solution should contain 1/5 teaspoon of merthiolate per 1 quart of water. Wipe the mask with a clean cloth and air dry.
(d) Replace the hose if it shows evidence of deterioration.
(e) Hoses may be cleaned in the same manner as the mask.
(f) Observe that each mask breathing tube end is free of nicks, and that the tube end will slip into the cabin oxygen receptacle with ease and not leak.
9-50. FUNCTIONAL TESTING AFTER REPAIR. Following repair, and before inspection plates, cover plates, or upholstering are replaced, test the entire system.
a. Open the cylinder valve slowly and observe the pressure gauge on a high-pressure system. A pressure of approximately 1,800 psi (at 70 °F) should be indicated on the gauge.
(Cylinder pressure will vary considerably with radical temperature changes.)
Par 9-50 Page 9-52
(1) Check the system by installing one of the mask hose fittings (minus the mask) in each of the cabin wall outlets to determine whether there is a flow. If a demand mask is used, check by breathing through the mask and, if appropriate, clean the mask according to subparagraph 9-49d.
(2) Check the complete system for leaks in accordance with the procedure outlined in subparagraph 9-49b(2)(d).
(3) If leaks are found, close the cylinder valve and open an outlet to reduce the pressure in the system to zero.
b. The following checks may be made for a pressure drop check of the system.
(1) Open the cylinder valve and pressurize the system. Observe the pressure gauge (a pressure of approximately 1,800 psi at 70 °F should be indicated). For the lightweight ICC 3HT 1850 cylinders, pressurize the system to approximately 1,850 psi at 70 °F.
(2) Close the cylinder valve and wait approximately 5 minutes for temperatures to stabilize.
(3) Record the pressure gauge reading and temperature and after 1 hour, record the pressure gauge reading and temperature again.
(4) A maximum pressure drop of 100 psi is permissible.
NOTE: Conduct the above tests in an area where changes of temperature will be less than 10 °F. If a leak occurs during the 1-hour period, suitable corrections would be required, or re-conduct the test under conditions of unvarying temperatures.
9-51. REQUIREMENTS FOR REQUALIFICATION OF OXYGEN CYLINDERS (refer to Title 49 of the Code of Federal Regulations (49 CFR) part 180, § 180.209). This is a Department of Transportation (DOT) requirement. Each cylinder that becomes due for periodic requalification must be hydrostatically tested every 5 years (10 years if it meets the requirements in 49 CFR § 180.209(b)). These cylinders carry a DOT 3AA classification and are suitable for the use intended. Cylinders that carry a DOT 3HT classification must be hydrostatically tested every 3 years, and must be retired from service after 24 years or 4,380 pressurizations, whichever occurs first. These cylinders must be stamped with an approval after being inspected (refer to 49 CFR § 180.209(k)).
CAUTION: Use only aviation breathing oxygen when having the oxygen bottle charged.
a. Charging High-Pressure Oxygen Cylinders. The following are recommended procedures for charging high-pressure oxygen cylinders from a manifold system, either permanently installed or trailer-mounted.
Par 9-51 Page 9-53 CAUTION: Never attempt to charge a low-pressure cylinder directly from a high-pressure manifold system or cylinder.
(1) Inspection. Do not attempt to charge oxygen cylinders if any of the following discrepancies exist:
(a) Inspect for contaminated fittings on the manifold, cylinder, or outside filler valve. If cleaning is needed, wipe with stabilized trichloroethylene and let air dry. Do not permit the solvent to enter any internal parts.
(b) Check the hydrostatic test date of the cylinder. DOT regulations require DOT 3AA designated cylinders be hydrostatically tested to 5/3 their working pressure every 5 years (10 years if they meet the requirements in 49 CFR § 180.209). Cylinders being designated as DOT 3HT (refer to 49 CFR § 180.209(k)) must be hydrostatically tested to 5/3 their working pressure every 3 years, and retired from service 24 years or 4,380 filling cycles after the date of manufacture, whichever occurs first.
(c) If the cylinder is completely empty, do not charge. An empty cylinder must be removed, inspected, and cleaned before charging.
(2) Charging.
(a) Connect the cylinder valve outlet or the outside filler valve to the manifold.
(b) Slowly open the valve of the cylinder to be charged and observe the pressure on the gauge of the manifold system.
(c) Slowly open the valve of the cylinder on the manifold system having the lowest pressure and allow the pressure to equalize.
(d) Close the cylinder valve on the manifold system and slowly open the valve of the cylinder having the next highest pressure. Continue this procedure until the cylinder has been charged in accordance with Table 9-5.
(e) Close all valves on the manifold system.
(f) Close the valve on the filled cylinder and remove the cylinder from the manifold.
(g) Using a leak detector, test for leakage around the cylinder valve threaded connections. (If leakage is present, discharge the oxygen and return the cylinder to the facility for repair.)
(h) Let the cylinder stabilize for a period of at least 1 hour, and then recheck the pressure.
(i) Make any necessary adjustments in the pressure.
Par 9-51 Page 9-54
b. Charging of Low-Pressure Oxygen Systems and Portables. For recharging a low-pressure aircraft oxygen system, or portable cylinders, it is essential that the oxygen trailer or cart have a pressure-reducing regulator. Military types E-2 or C-1 reducing regulators are satisfactory. These types of regulators reduce the large cylinder pressure from 2,000 psi to a line pressure of 450 psi. (A welding pressure-reducing regulator is not satisfactory.)
CAUTION: When refilling the low-pressure system or portable cylinders, open the oxygen filler tank valve slowly to allow the system or portable cylinders to be filled at a slow rate. After the refilling operation is completed, check for leaks with a leak detector. If a leak is detected, subparagraph 9-49b(2)(d) should be referred to for corrective action.