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.
Par 9-51 Page 9-55 TABLE 9-5. TABLE OF FILLING PRESSURES Initial Temp (°F) Filling Pressure (psi) 0 1,650 10 1,700 20 1,725 30 1,775 40 1,825 50 1,875 60 1,925 70 1,975 80 2,000 90 2,050 100 2,100 110 2,150 120 2,200 130 2,250 Initial Temperature: Refers to the ambient temperature in the filling room.
Filling Pressure: Refers to the pressure to which aircraft cylinders should be filled. This table gives approximations only, and assumes a rise in temperature of approximately 25 °F due to the heat of compression. This table also assumes the aircraft cylinders will be filled as quickly as possible and that they will only be cooled by ambient air, with no water bath or other means of cooling being used.
Example: If ambient temperature is 70 °F, fill aircraft cylinders to approximately 1,975 psi—as close to this pressure as the gauge may be read. Upon cooling, cylinders should have approximately 1,850 psi pressure.
9-52. –9-59. [RESERVED.]
Par 9-60 Page 9-56 SECTION 4. CABIN INTERIOR
9-60. GENERAL. The requirements related to fire protection qualities of cabin interior materials are specified in Civil Air Regulation (CAR) 3.388, fire precautions or 14 CFR part 23, § 23.2325.
9-61. CAR 3 AIRCRAFT INTERIOR. The requirement for an interior of a CAR 3 aircraft that is used only in 14 CFR part 91 operations, where smoking is not permitted, is that the materials shall be flash-resistant. (Refer to CAR 3.388.)
a. For compartments in CAR 3 aircraft where smoking is permitted, the wall and ceiling linings, the covering of all upholstering, floors, and furnishings shall be flame-resistant.
Such compartments should be equipped with an adequate number of self-contained ash trays. All other compartments shall be placarded against smoking. (Refer to CAR 3.388.)
(1) If fabric is bought in bulk to refurbish the interior, seats, and ceiling liners for a CAR 3 aircraft used in part 91 operations, a manufacturer’s statement, declaring that the material meets ASTM International or similar national standard for either flash resistance or flame resistance, would be acceptable, but only for a CAR 3 aircraft installation. (Refer to § 43.13(a).)
A manufacturer’s statement is acceptable due to neither the Civil Aeronautics Administration (CAA) nor the FAA having published an FAA fire standard for either flash or flame resistance for interior materials for CAR 3 aircraft. Since the FAA would accept and recognize a national standard, the mechanic would reference the manufacturer’s statement and the national standard that the material meets in the aircraft’s maintenance records.
(2) If an annual inspection is performed on a CAR 3 aircraft with a new interior and there is no mention of a manufacturer’s statement that the fabric is flash- or flame-resistant as applicable, the possibility exists that the fabric is an unapproved part. The mechanic should take the necessary steps to ensure that the fabric meets or exceeds ASTM International or national standards.
(3) If an FAA-approved Supplemental Type Certificate (STC) interior kit is installed in a CAR 3 aircraft, and the material and fabric in the kit are Parts Manufacturer Approval- (PMA) or TSO-approved, the mechanic should include the STC number in block 8 of FAA Form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance).
b. It is recommended that for all CAR 3 interiors to use only fabric and materials that meets the more stringent requirements of part 23 appendix F.
9-62. PART 23 AIRCRAFT INTERIOR. Materials used in part 23 aircraft interiors must meet the requirements of § 23.2325.
a. If the fabric is bought in bulk to refurbish a part 23 aircraft, then the fabric must meet the part 23 burn requirements. A burn test would have to be done on samples of the material and fabrics by an approved and rated FAA Repair Station. That FAA Repair Station would certify that all the material and fabrics meet part 23 appendix F requirements. The mechanic would include that repair station’s statement in the aircraft’s records.
Par 9-62 Page 9-57
b. If an STC-approved interior kit with either PMA- or TSO-approved materials for a part 23 aircraft is bought, the mechanic would only have to reference the STC number on FAA Form 337 and the aircraft’s records. Part 23 appendix F would not be required.
c. If an annual inspection is to be performed on a part 23 aircraft in which a new interior was installed, but the aircraft’s records do not reflect that a burn test was performed on the interior’s materials and fabric by an FAA Approved Repair Station, or there is no mention of an STC or FAA Form 337 in the aircraft records, then a burn test that meets part 23 appendix F must be accomplished before the aircraft is approved for return to service.
9-63. SOURCE OF INFORMATION. If information regarding the original or properly altered fire protection qualities of certain cabin interior materials is not available, requests for this information should be made to the aircraft manufacturer or the responsible Flight Standards office, specifying the model aircraft, the aircraft manufacturer, the date the aircraft was manufactured or the serial number, and the 14 CFR part under which the aircraft is operated
(i.e., CAR 3, 14 CFR part 91, or 14 CFR part 121, etc.).
9-64. UPHOLSTERY AND/OR BELTS. Upholstery and/or belts that have been washed may lose some or all of their fire-resistant qualities. Unless the soap is completely removed from the cloth, the strength of the material may be significantly reduced. Consult the manufacturer to determine how to maintain the fire-resistant qualities.
9-65. –9-70. [RESERVED.]
Par 10-1 Page 10-1 CHAPTER 10. WEIGHT AND BALANCE SECTION 1. TERMINOLOGY
10-1. GENERAL. The removal or addition of equipment results in changes to the center of gravity (CG). The empty weight of the aircraft, and the permissible useful load are affected accordingly. Investigate the effects of these changes, since the aircraft flight characteristics may be adversely affected. Information on which to base the record of Weight and Balance (W&B) changes to the aircraft may be obtained from the pertinent Aircraft Specifications, Type Certificate Data Sheet (TCDS), prescribed aircraft operating limitations, Aircraft Flight Manual (AFM), aircraft W&B report, and maintenance manual. Removal of standard parts with negligible weight or addition of minor items of equipment such as nuts, bolts, rivets, washers, and similar standard parts of negligible weight on fixed-wing aircraft do not require a W&B check. Rotorcraft are, in general, more critical with respect to control with changes in the CG position. Refer to the procedures and instructions in that particular model’s maintenance or flight manual.
10-2. TERMINOLOGY. The following terminology is used in the practical application of W&B control.
a. Maximum Weight. The maximum weight is the maximum authorized weight of the aircraft and its contents as listed in the specifications.
b. Empty Weight. The empty weight of an aircraft includes all operating equipment that has a fixed location and is actually installed in the aircraft. It includes the weight of the airframe, powerplant, required equipment, optional and special equipment, fixed ballast, full engine coolant, hydraulic fluid, residual fuel, and oil. Additional information regarding fluids that may be contained in the aircraft systems and must be included in the empty weight will be indicated in the pertinent Aircraft Specifications or TCDS.
c. Negligible Weight Change. Any change of one pound or less for aircraft whose weight empty is less than 5,000 lb.; 2 lb. or less for aircraft whose weight empty is more than 5,000 and 50,000 lb.; and 5 lb. or less for aircraft whose weight empty is more than 50,000 lb. Negligible CG change is any change of less than 0.05 percent mean aerodynamic chord (MAC) for fixed-wing aircraft, 0.2 percent of the maximum allowable CG range for rotary wing aircraft.
d. Useful Load. The useful load is the empty weight subtracted from the maximum weight of the aircraft. This load consists of the pilot, crew (if applicable), maximum oil, fuel, passengers, and baggage unless otherwise noted.
e. Weight Check. The weight check consists of checking the sum of the weights of all items of useful load against the authorized useful load (maximum weight less empty weight) of the aircraft.
f. Datum. The datum is an imaginary vertical plane from which all horizontal measurements are taken for balance purposes with the aircraft in level flight attitude. The datum is indicated in most Aircraft Specifications or TCDS. On some of the older aircraft, when the datum is not indicated, any convenient datum may be selected. Once the datum is selected, all