AC 43.13-2A Rev. 1977 of nickel-cadmium battery cases, one with vent nozzles and the type with viewports.
a. The vent nozzle type utilizes vent hoses to evacuate the gas overboard by use of forced air
- DI - REPLACEMENT or by venturi effect.
BATTERY b. Battery cases with viewports or louvers must OUTLINE have an air flow sufficient to keep the mixture of air and hydrogen below 4 percent. The gases from this type of case are evacuated into the battery compartment. Regardless of the ventilation system used, the air flow should be a minimum of 5 cubic feet per minute.
ORIGINAL
LEAD-ACID
BATTERY C.G. (WI)
REPLACEMENT
NICKEL-CADMIUM BATTERY C.G. (Wz) FIGURE 10.7.-Change in cantilever support battery overhang moment.
Example:
Original Overhang Moment with Lead- Acid Battery W1 = 25 1b., D1 = 4 inches 4 inches X 25 1b., = 100 in. - 1b.
New Overhang Moment with Replacement Nickel-Cadmium Battery Wz = 19.5 1b., Dz = 6 inches 6 inches X 19.5 1b. = 117 in. - 1b.
201. VENTILATION. During the charging process, nickel-cadmium batteries produce hydrogen and oxygen gases. This occurs near the end of the charging cycle when the battery reaches what is called the gassing potential. To avoid a buildup of these gases, and possible accidental ignition, ventilation should be provided to evacuate this gas from the aircraft. There are two types
202. PREINSTALLATION REQUIREMENTS. Inspect the replacement battery for possible damage incurred during shipment or storage. Give particular attention to signs of spilled liquid within the shipping container, as it may indicate a damaged cell. Follow procedures outlined in Section 2 for battery venting and electrical connec tions.
a. Preinstallation battery servicing. Check at least the following in accordance with the battery manufacturer's instruction:
(1) Remove the shipping plugs (if used) and clean and install the filler cap vent plugs.
(2) Check the tightness of terminal hardware including each cell connector strap to the proper torque values.
(3) Check the polarity of each cell to be sure they are connected in the proper series or sequence.
(4) Charge and check battery voltage and electrolyte level.
b. Compartments or battery boxes which have previously housed lead-acid batteries must be washed out, neutralized with ammonia or a baking soda solution, allowed to dry thoroughly, and painted with alkaline-resistant paint. Remove all traces of sulfuric acid and its corrosion products from the battery vent system to prevent contamination of the potassium hydroxide electrolyte and/or possible damage to the cell case material. Replace those parts of the vent system which cannot be thoroughly cleansed (hoses, etc.). When sump jars are incorporated into the vent system, replace the old pad with a new one that has been saturated in a three-percent solution (by weight) of boric acid and water.
82 Chap 10
Rev. 1977
203. SECURING THE BATTERY. Follow the procedures outlined in Section 2 of this chapter.
Make certain that the holddown bolts are not drawn up so tightly that the battery case/cover becomes distorted. Should the cover become distorted, there is a possibility that the cell terminal hardware may eventually puncture the neoprene cover liner used in many batteries, and short Caution: In installations where care has been taken to isolate the battery cases, inadvertent grounding may occur through improper or careless use of safety wire. Use no wood in nickelcadmium battery boxes as it becomes conductive with time causing a current flow from the battery case to ground. Use only fiberglass or other acceptable material as liners and spacers in the battery box.
204. VOLTAGE AND CURRENT REGULATION. It is essential that the charging voltage and current be checked and, if necessary, the voltage regulator reset to meet the requirements of the nickelcadmium battery being installed. IMPORTANT -improper charging current or voltage can destroy a battery in a short period of time.
Chap 10 AC 43.13-2A
205. WEIGHT AND BALANCE. After installation of the nickel-cadmium battery the weight and balance of the aircraft should be recomputed if:
a. The weight of the nickel-cadmium battery is different from that of the original lead-acid battery.
b. The location of the nickel-cadmium battery is different from that of the original lead-acid battery.
Weight and balance procedures for aircraft are contained in chapter 13 of AC 43.13-1A.
206. RESTORATION OF LEAD-ACID BATTERIES.
When lead-acid batteries are restored in lieu of nickel-cadmium batteries the procedures contained in sections 1, 2, and 3 of this chapter should be used. Structural requirements are referenced in paragraph 199 and figure 10.7.
Airframe protection is specified in paragraph
177. Follow the procedures outlined in section 2 of this chapter for battery security, battery venting, and battery drains. Assure that all electrical requirements have been accomplished.
Place emphasis on aircraft weight and balance.
Refer to chapter 13 of AC 43.13-1A.
207.-210. [RESERVED] 83
Rev. 1977 AC 43.13-2A Chapter 11. ADDING OR RELOCATING INSTRUMENTS
211. GENERAL. This chapter contains struc- niques, and Practices--Aircraft Inspection and tural and design information to be considered Repair," chapter 2, section 3, for methods and when aircraft alterations involving the addition techniques of retaining structural integrity.
and relocation of instruments are being made. b. Plumbing. Refer to the manufacturer's in-
212. PREPARATION. First determine what regu- structions for fabrication, routing and installalation, (CAR 3, 4b, FAR 23, 25, etc.) is the tion of instrument system lines. Advisory Cirbasis for the aircraft type certificate. That regu- cular 43.13-1A provides information regarding lation establishes the structural and performance the installation and fabrication of aircraft plumbrequirements to be considered when instruments are to be added or relocated. c. Vacuum Source. Minimum requirements strument panel installation. vides information by which structural integrity may be determined. Chapter 2, paragraph 23a through f provides information pertinent to in- a. Structure. Chapter 1 of this handbook pro- ments: Installation." for installation and performance of instrument vacuum systems are covered in the applicable FAR Airworthiness Standards under "Instru- (1) In the absence of specific requirements
b. Location. Consult the applicable regulation tor vacuum pump installation, refer to FAR Part 25, section 25.1433 for guidance. It is detion and arrangement. for the specific requirements for instrument loca- sirable to install a "T" fitting between the pump and relief valve to facilitate ground checking and
(1) In the absence of specific requirements, adjustment of the system.
installation of IFR flight instruments in a "T" (2) When a venturi tube power source is arrangement is recommended. Locate the air- used, it should not be taken for granted that a craft attitude indicator at top center, airspeed venturi will produce sufficient vacuum to propindicator to the left, altimeter to the right and erly operate one or more instruments. Many of directional indicator directly below, thus form- the venturi tubes available for aircraft have a flow ing the letter "T. When a radio altimeter is rate of approximately 2.3 cubic feet per minute used, the indicator may be placed on the im- at 3.75 inches of mercury (in. Hg) vacuum.
mediate right of the attitude indicator with the Therefore, it is essential that the vacuum load pressure altimeter to the right of the radio altim- requirements be carefully evaluated.
eter indicator. (3) Vacuum loads may be calculated as fol-
213. INSTALLATION. Mount all instruments so they are visible to the crewmember primarily (a) Gyroscopic instruments require optiresponsible for their use. Mount self-contained mum value of airflow to produce their rated rotor gyroscopic instruments so that the sensitive axis speed. For instance, a bank and pitch indicator is parallel to the aircraft longitudinal axis. requires approximately 2.30 cubic feet per minute 23a through f of this handbook. Refer to the Circular 43.13-1A, Acceptable Methods, Tech- aircraft manufacturer's instructions and Advisory such as adding holes in the instrument panel to mount instruments, refer to chapter 2, paragraph a. Structure. When making structural changes per minute and a pressure drop of 4.00 in. Hg. indicator consumes approximately 1.30 cubic feet would be marginal. Similarly, the directional gyro The turn and bank indicator has a flow require- of 4.00 in. Hg. Therefore, operating an instru- ment requiring 4.00 in. Hg from one venturi for its operation and a resistance or pressure drop Chap 11 85
Rev. 1977 AC 43.13-2A ment of 0.50 cubic feet per minute and reaches this flow at a pressure drop of 2.00 in. Hg. The Table 11.2.-Equivalent straight tube line drops for 90° elbows.
above instruments are listed in Tables 11.1 and Pressure drop in a 90° elbowo
11.3. Optimum values are shown in Table 11.3. Tubing size in terms of length of straight It should be noted that the negative pressure tube equivalent to a 90° elbow air source must not only deliver the optimum O.D inch Wall thickness inch Feet value of vacuum to the instruments, but must ¼ .035 0.28 Table 11.1.-Instrument air consumption.
.035 0.46 dir consumption at -042 0.62 sea level .042 0.81 Instrument Differential drop in. Hg Cubic ¾ .049 0.98 suction feet/per (Optimum) minute 1 .049 1.35 AUTOMATIC PILOT SYSTEM 3 Determine the pressure drop through Directional gyro control unit (Types A-2, A-3, & A-3A) across mount assembly 5.00 2.15* 22.48 feet (20 feet + 2.48 equivalent feet) of ½ O.D. X .042 tubing at 4.10 CFM flow. From fig- Bank & climb gyro control unit ure 11.1, pressure drop per each 10-foot length = across mount assembly 5.00 3.85* 0.68 in. Hg. Divide 22.48 feet of tubing by 10 to Total 6.00* obtain the number of 10-foot sections, i.e., AUTOMATIC PILOT SYSTEM Directional gyro control unit (Type A-4) 5.00 3.50* 22.48 ÷ 10=2.248. Multiply the number of sec- tions by 0.68 in. Hg to obtain the pressure drop Bank & climb gyro control unit 5.00 5.00* through the system. (0.68 X 2.248=1.53 in. Hg) Total 8.50* 4 The pump must therefore be capable Bank & pitch indicator Directional gyro indicator 4.00 4.00 2.30 1.30 of producing a minimum pressure differential of Turn & bank indicator 2.00 .50 Table 11.3.-Differential pressure across instrument (*) Nore.—Includes air required for operation of pneumatic inlet and outlet.
relays.
Suction in inches also have sufficient volume capacity to accom- of mercury modate the total flow requirements of the various Instrument Mini- Opti- Maxiinstruments which it serves. mum mum mum
(b) To calculate the flow requirements of elbows and 20 feet of line (½ O.D. x .042) tub- a simple vacuum system, assume four right-angle AUTOMATIC PILOT SYSTEM (Types A-2, A-3, & A-3A) ing Directional gyro control unit across mount assembly 4.75 5.00 5.25 1 Assume the flow requirements for: Bank & climb gyro control unit Turn & bank indicator .50 CFM across mount assembly 4.75 5.00 5.25 Directional gyro indicator Bank & pitch indicator 1.30 CFM 2.30 CFM Gauge reading (differential gauge in B & C control unit) 3.75 4.00 4.25
AUTOMATIC PILOT SYSTEM Total flow required 4.10 CFM (Type A-4) Directional gyro control unit 3.75 5.00 5.00 O.D. x .042 elbow is equivalent to 0.62 feet of Bank & pitch indicator Bank & climb gyro control unit 3.75 3.75 5.00 4.00 5.00 5.00 Directional gyro indicator 3.75 4.00 5.00 sure drop of four 90° elbows is equivalent to 2.48 Turn & bank indicator 1.80 2.00 2.20 feet of tubing.
Chap 11 86
Rev. 1977 AC 43.13-2A
• 035 PRESSURE DROP PER TEN FOOT LENGTH - INCHES OF MERCURY 1/4 x 035 TUBING SIZE 5/16 x 3/8 × .035 • 042 1/2 x 5/8 x • 042 3/4 x • 049
0.15 1 x
0.1
0.5 0.75 1 1.5 2 3 4 5 6 8 10 15 20
AIR FLOW - CUBIC FEET PER MINUTE
PRESSURE DROP DATA FOR SMOOTH TUBING FIGURE 11.1 Chap 11
AC 43.13-2A
5.53 in. Hg, i.e., 4.00 in. Hg for maximum instrument usage + 1.53 in. Hg (determined) at a flow of 4.10 cubic feet per minute.
d. Filter. Filters are used to prevent dust, lint and other foreign matter from entering the instrument and vacuum system. Filters may be located at the instrument intake port or at the manifold intake port when instruments are interconnected. Determine that the capacity of the filter is as great or greater than the capacity of the vacuum system. Assure that there is no pressure drop across the filter media.
e. Electrical Supply for Instruments. Guidelines for the installation of instrument electrical wiring and power source are provided in Advisory Circular 43.13-1A, chapter 11, sections 2 and 3, and Chapter 16, section 3.
NorE: Strict conformance to the shielding specifications supplied by compass manufacturers is recommended in all installations to eliminate any possibility of spurious
f. Instrument Lighting. Instrument lighting must be installed in accordance with the regulations that are applicable to the aircraft type cer- sine it yes or.
reflection of the lights is unsatisfactory, provide a shield or a means for controlling the intensity of illumination.
g. Magnetic Headings. Calibrate magnetic instruments with the powerplants operating. After this initial calibration, switch all nav/com and electrical equipment, such as windshield wipers and defrosters, "on" to determine if any electrical system interference affects the instrument calibration. If the calibration is affected, prepare an instrument placard identifying the compass headings with the equipment "on" and also with the equipment "off." Placard in accordance with par. 214f of this chapter.
88 Rov. 1977
214. TESTING, MARKING, AND PLACARDING.
a. Testing the Venturi Tube-Powered Systems.
At normal inflight cruise speed, check the venturi tube-powered system to assure that the required vacuum pressure is being supplied.
b. Testing the Vacuum Air Pump Powered System. When the system is powered by vacuum air pumps, check the system while the pumps are operating at their rated r.p.m. and measure the vacum available to the instruments.
c. Testing of Altimeters and Static Systems.
When checking the operation of an altimeter static system to determine that the system is free of any contaminating materials, be sure to disconnect the plumbing from all air operated instruments before purging the lines with dry air or nitrogen since the pressure necessary for purgmay damage any connected instrument.
Static system test procedures are provided in FAR 43, Appendix E.
d. Testing electrical supply (instruments). Check the voltage at the instrument terminals and determine that it is equal to the manufacturer's recommended values.
e. Fuel, Oil, and Hydraulic (Instrument Supply).
Measure the fluid pressure at the instrument end of the line to determine whether it is equivalent to that at the pressure source.
f. Instrument Markings and Placards. When additional instruments are installed they must be appropriately marked. Refer to the applicable CAR/FAR under "Markings and Placards" for specific instrument marking and placard requirements.
215.-240. [RESERVED] Chap 11
Rev. 1977 AC 43.13-2A Chapter 12. LITTER, BERTH, AND CARGO TIEDOWN DEVICE INSTALLATIONS
241. GENERAL. This chapter provides data for and Repair") Commercially available litters or down device installations in airplanes and rotor- making acceptable litter, berth, and cargo tie- installation and load criteria. stretchers may be utilized provided they meet craft. Prior to proceeding with the alteration, determine the airworthiness standards applicable aphragm, or other means at the forward end of Provide a padded end board, canvas dito the contemplated alteration. Refer to the each litter or berth that will withstand the total proper volume of the FAA publication "Type Certificate Data Sheets and Specification" for the litters and berths installed parallel to the air- forward static test load. Safety belts used for certification basis of the aircraft involved. When airworthiness standards pertinent to the airplane craft's longitudinal axis are not required to with- stand forward loads as these loads are to be involved are not available, current airworthiness taken up by the padded end boards.
standards may be used. For example, FAR 23, Design litters or berths intended for adults for 25, 27, or 29, as applicable, may be used in place occupants weighing at least 170 Ibs. In those of CAR 4a, 4b, 6, or 7 or Bulletin 7a. instances where litters or berths are for children,
242. INSTALLATION CONSIDERATIONS. design the installation for the maximum intended weight. See paragraph 247 for placarding.
erated within the weight and center of gravity a. Assure that the altered aircraft can be op- tendants or other passengers that will be carried Provide approved seats for any cabin atranges. Refer to chapter 1, paragraph 9 of this when litters are installed.
handbook. b. Cargo tiedown devices may be assembled
b. Determine that there will be free access to from webbing, nets, rope, cables, fittings, or other all equipment and controls essential to the proper material which conforms to NAS, TSO, AN, operation of the aircraft, required emergency MIL-SPEC, or other acceptable standards. Use exits, and emergency equipment. snaps, hooks, clamps, buckles, or other acceptable
c. Use only materials that are at least flame- fasteners rather than relying upon knots for seresistant for covering of floors, litters, or berths. curing cargo. Install tensioning devices or other Refer to the applicable airworthiness standards means to provide a method of tightening and for the aircraft involved to determine the re- adjusting the restraint system to fit the cargoes quired flame-resistant qualities. For aircraft in to be carried.
Provide covers or guards where necessary to prevent damage to or jamming of the aircraft's equipment, structure, or control cables.
tion of cargo with respect to passengers, cargo 244. STRUCTURAL ATTACHMENT. Commercially compartment, or aisle width. available seat tracks, rails, or other types of
243. FABRICATION AND INSTALLATION. ment, provided they conform to an accepted anchor plates may be used for structural attachtubing, sheet metal, extrusions, canvas, webbing, a. Litters and berths may be fabricated from standard (see chapter 1, paragraph 6). This type of hardware permits a ready means of methods, techniques, and practices. visory Circular 43.13-1A "Acceptable Methods, or other suitable material, using acceptable (Ref. Ad- mounting a wide variety of quick-disconnect fittings for litters, berths, and cargo tiedown. Typical examples of such fittings and their at- Techniques, and Practices-Aircraft Inspection tachment are shown in figures 12.1 through 12.5.
Chap 12 89
AC 43.13-2A Rov. 1977
EXTRUDED TRACK ANCHOR PLATE Light duty Medium duty Heavy duty ces Extruded track and anchor plates are available in several different styles and load capacities and will accommodate a wide variety of quick attachment fittings.
SINGLE PIN TYPE SINGLE PIN TYPE
HOLD DOWN FITTINGS CARGO TIE DOWN FITTINGS Adjustable These types of fittings are suitable for litter or berth attachment to the extruded track and anchor plate styles shown above.
These types of fittings are suitable for cargo tie down attachment to the extruded track and anchor plate styles shown above.
DUAL PIN TYPE CARGO TIE FITTINGS 360° Rotation Low profile n These types of cargo tie down fittings are of greater capacity than the single pin types and are suitable for use with the extruded track style shown above.
FIGURE 12.1. Extruded track, anchor plates, and associated fittings.
90 Chap. 12
Rev. 1977 AC 43.13-2A
PAN FITTINGS SINGLE STUD FITTINGS Stud & Cargo ring Cargo ring only Stud only Round head Hex head
SINGLE STUD CARGO TIE DOWN FITTING
SINGLE STUD HOLD DOWN FITTINGS Lift to release These types of fittings are suitable for cargo tie down attachment to the single stud fittings or stud equipped pan fittings shown above.
STUD/RING These types of fittings are suitable for litter or berth attachment to the single stud fittings or stud equipped pan fittings shown above.
EYE BOLT These types of fittings are suitable for litter, berth, and/or cargo tie down attachment directly to the aircraft structure.
FIGURE 12.2. Miscellaneous litter, berth, and cargo tiedown fittings.
Chap 12 91
AC 43.13-2A Rev. 1977 A. Attachment method utilizing a honeycomb doubler.
Single Studs or Eye Bolts.
Pan Fittings.
B. Attachment methods utilizing reinforcing plates.
Stud/Rings.
1. Bed all inserts and spacers in a suitable potting compound.
2. Reinforcing plate.
3. Where fitting is subject to rotation, place washers on both sides and use a positive safety means.
4. (Alternate method in lieu of spacers) Undercut honeycomb, inject potting compound, and drill through when set.
5. Countersink if required for clearance or if desired for appearance.
6. Undercut all open edges of honeycomb 1/16" and seal with potting compound.
7. Honeycomb doubler.
8. Use epoxy or other suitable adhesive to attach doubler and reinforcing plates.
FIGURE 12.3. Typical attachment of fittings to honeycomb structures.
92 Chap 12
Rev. 1977 AC 43.13-2A
EXTRUDED TRACK, · > FLOOR BEAM (Reinforce cut out as neccessary to retain strength.)
UNDERFLOOR REINFORCEMENT
FLOOR BEAM DOUBLER/ATTACH ANGLE FIGURE 12.4. Installation of underfloor support for extruded track.
Chap 12 93
AC 43.13-2A Rev. 1977
THREE BAR TYPE SLIDE Rigging for easiest adjustment and moderate loads.
applicable When Rigging for maximum load whether slide is joggled or not.
TYPICAL NAS STRAP ASSEMBLY Available with various types of end hardware and up to 5000 capacity.
TENSIONING SLIDE Used to preload cargo tie down straps.
Handhold
CARGO BARRIER NET
CARGO TIE DOWN NET Commonly used to restrain bulky or composite cargo.
Chap 12 FIGURE 12.5. Typical cargo tiedown straps and cargo nets.