AC 43.13-2A Rev. 1977 manufacturer's installation procedures and assure that the balun is properly grounded to the airframe. Refer to AC 43.13-14 'Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repairi chapter 11, for acceptable bonding practices.
ANTENNA
DIPOLES FIGURE 3.7.-Preferred VOR antenna location for maximum signal pickup with minimum ignition interference.
CUT STRINGER
REINFORCING DOUBLER OF ALCLAD 2024 - I2 BALUN
WIRE WRAPPED AND
SOLDERED TO SHIELD
AIRFRAME GROUND FRAME
STRINGER
STRINGER
DOUBLER FLANGES RIVEIS ADDED
AT LEAST THE HEIGHT AS SHOWN ON
OF CUT STRINGER RAMES, STRINGE
AND DOUBLE
• EXISTING RIVETS FIGURE 3.8.-Typical antenna installation involving a cut stringer.
airplanes is over the forward part of the cabin.
Mount the rigid V-type antenna so that the apex of the "V" points forward and the plane of the "V" is level in normal flight.
a. VOR Antenna Balun and Transmission Lines.
A dual element or balanced antenna system requires a balun or an impedence matching device for maximum signal transfer into an unbalanced coaxial cable. Rigid antennas, as displayed in figure 3.4, incorporate a balun as an integral component of the antenna assembly. Follow the 16 FIGURE 3.9 Typical dipole antenna assembly.
(2) Figure 3.10 is an illustration of a typical VOR antenna balun. A balun made from a section of the transmission line functions as a tuned circuit or transformer which produces a standingwave ratio to provide the desired matching impedence. When the antenna is matched to the line, the line measurement in multiples of wave lengths is not critical.
(2) Radio wave velocity is less in a cable than in air; therefore, the wave length in cable will be shorter than in air. Appropriate test equipment must be used for transmission line measurements because the physical and electrical lengths of lines are not always equal.
Chap 3
Rev. 1977 AC 43.13-2A a lengthwise slit and peel off the outer jacket.
AT TACH Do not nick, cut or damage the shield.
TO ANTENNA DIPOLES
SHIELD (OUTER - DIELECTRIC
CONDUCTOR)
TWISTED SHIELD SHIELD
REMOVED OUTER JACKET
CENTER CONDUCTOR
SINGLE SHIELD
- PROTECTIVE OUTER FIGURE 3.11 Coaxial cable preparation.
COVERING
(2) Comb out the braid and bend back to expose the dielectric. Use a sharp knife to cut the dielectric around the circumference, not quite through to the center conductor. Do not nick or cut the conductor. Remove the dielectric by twisting and pulling.
(3) Solder the contact to the center conductor. Use a clean, well-tinned soldering iron.
ROSIN-CORE WIRE WRAPPED AND SOLDERED TO SHIELD SOLDER 60/40
- AIRFRAME GROUND -CENTER CONDUCTOR OPEN
TO NAVIGATION RECEIVER FICURE 3.10 Typical VOR antenna balun.
(3) The transmission line should be kept as shore a short as possible. Any bends in the cable should have at least a 3-inch radius. Follow the equipment manufacturer's recommendations regarding transmission lines and lengths.
b. Assembly of Coaxial Cable Connectors.
Optimum performance of a radio system is dependent upon the coaxial cable connector assembly. Follow the manufacturer's assembly instructions. Assure that the cable is not distorted or flattened when cutting. The electrical characteristics of the cable change when flattened or bent sharply.
(1) To remove the outer jacket, cut with a sharp knife around the circumference, then make Chap 3 FIGURE 3.12 Coaxial cable tinning center lead.
(4) Do not apply heat too long as this will swell the dielectric and make it difficult to insert into the body of the connector.
FLUSH AGAINST DIELECTRIC 7 CONTACT MUST BUTT
ROSIN-CORE SOLDER 60/40
FEED SOLDER INTO
HOLE ONLY FIGURE 3.13 Coaxial cable soldering center lead.
(5) Install connector body and tighten until secure. Do not overtighten as this will distort the cable.
Rev. 1977 AC 43.13-2A VOR receivers. Typical cable lengths are from 22 to 35 inches and multiples of these lengths.
- 1/4 Another method of coupling two VOR navigation receivers to a common antenna is by utilizing DO NOT BREAK STRANDS. a device called a coupler or diplexer. This de-
DO NOT NICK CENTER CONDUCTOR-
• 1/8
NUT WASHER GASKET CLAMP TRIM STRANDS WITH SCISSORS VERTICAL "V" ANTENNA
FLUSH WITH END OF TAPER → L3/32
CONTACT FLUSH WITH END OF INSULATOR
JACK BODY
INSULATOR -CONTACT FICURE 3.14 Coaxial cable install connector body.
(6) Use only the crimping tool recommended by the manufacturer, or an equivalent tool when installing connectors which utilize a crimp-type contact.
c. Dual VOR/NAV Receiver Installations. Iwo VOR navigation receivers can be connected to a common VOR antenna. This is accomplished by utilizing a coaxial tee connecter (UG-274 A/U) and matched 0.5 wavelength coaxial cable lengths connected from the tee connector to the respective UNDE: JURFACE OF AIRPLANE "p" ANTENNA "L" ANTENNA NOTE: AN "L" TYPE ANTENNA IS SIMILAR TO A "T"
ANTENNA EXCEPT THAT THE LEAD-IN WIRE
IS CONNECTED TO THE END OF THE ANTENNA INSTEAD OF THE CENTER.
FIGURE 3.15.-Typical wire antenna locations.
-TO RECEIVER
SOLDER CONNECTION MINIMUM 16 COPPERWELD ANTENNA WIRE' FiGURE 3.16.- Typical marker beacon receiving antenna.
Chop 3 |
Rev. 1977 1025 STEEL FITTING SPRING
FABRIC WING
• STEEL ROD WASHER NUT
METAL WING 2017 FIGURE 3.17.-Typical wing tip installations.
vice, in addition to impedance matching, also provides isolation between VOR navigation receivers while keeping line insertion losses at a minimum.
40. RANGE RECEIVING ANTENNAS. Mount T", "L", or "V" antennas on top or bottom of the aircraft with approximately 1-foot clearance from the fuselage and wings. Typical wire antenna installations are shown in figures 3.15 through 3.19.
41. MARKER RECEIVING ANTENNA. The marker receiver operates at a frequency of 75 MHz. In order to keep to a minimum the number of antennas on the aircraft, the marker receiver may utilize the same antenna as the range receiver if that antenna is mounted on the underside of the aircraft. However, both receivers should include provisions to permit simultaneous opera- Chap 3 AC 43.13-2A tion without interference. A whip or other vertical type of antenna should not be used for marker reception since the ground facility transmits from a horizontally polarized antenna.
4130
OR AN BOLT AND NUT 1025 STEEL
THIMBLE SPRING
FIN TAIL POST RUDDER:
1025 OR 4130 TUBE
RUBBER TENSION UNIT FIGURe 3.18.-Typical in tip installations.
42. ATC RADAR BEACON (TRANSPONDER) AND
DISTANCE MEASURING EQUIPMENT (DME) AN- TENNAS. Locate these antennas at an unobstructed location on the underside of the fuselage.
preferably at the lowest point of the aircraft when in level flight. To the extent practicable, mount the antenna so that the base is horizontal when the aircraft is in cruise attitude.
a. Installation. Mount the antennas at least 36 inches away from obstructions and as far as possible from other antennas. Tests have shown that the location of the antenna with respect to obstructions is of greater importance than having the antenna installed in a vertical position.
However, signal strength and pattern become noticeably affected as the angle of the antenna approaches 45° from the desired vertical position.
On fabric-covered aircraft or aircraft with other types of nonmetallic skin, it will be necessary to provide a flat metallic surface or ground plane" extending at least 12 inches in all direc- 19
AC 43.13-2A Rev. 1977
ANCHOR CABLE COIL SPRING
INSULATORS
DOUBLER FIGURE 3.19.- Typical wire antenna installations.
FIGURE 3.20.--Preferred position for distance measuring and/or ATO radar beacon antennas.
tions from the center of the antenna. Be sure the antenna makes a good, direct electrical connection with the ground plane. Install gaskets, pressurization seals, and/or sealant as required.
b. Dual System Installations. When dual ATC radar systems, dual DME systems, or combinations of these systems are installed, determine that the separation between their respective antennas is within the manufacturer's prescribed limits. (See paragraph 27i for mutual interference in DME and ATC radar beacon systems.)
c. Antenna Cable. Route the antenna cable in the most direct path practicable. Since losses can be relatively high at these frequencies, follow the equipment manufacturer's recommendations regarding transmission lines and lengths.
43. DIRECTION FINDING ANTENNAS (100 to 1750 KHz). Manual or automatic loop-type antennas are used with direction-finding receivers. The loops are designed for use with a particular receiver. Connecting wires between the loops and receivers are also designed for the specific equipment. Accordingly, only components meeting the specification characteristics of the receiver manufacturer should be used.
Chap 3
Rev. 1977 AC 43.13-2А
a. Loops enclosed in streamlined housings or exposed loops are satisfactory for external mounting on an aircraft. Loops may also be flush mounted on the aircraft when proper attention is given to avoid interference from metallic structure and skin of the aircraft.
c. Installation kits are designed for either top or bottom fuselage mounting of loop and sense antennas, or a combination of these two locations.
Particular attention should be paid to the manufacturer's installation instructions for antenna location (top or bottom) and loop output connections, in order to prevent 180° errors in bearing indications.
< >
INTERNAL LOOP
ENCLOSED LOOP FIGURE 3.21.-Typical ADF antenna installations.
b. Sense antennas are used to resolve radio bearing ambiguity in direction finding systems.
The sense and its lead-in must be matched to the input capacitance of the ADF receiver. The sense antenna capacitance is a function of length, spacing between antenna and fuselage, and leadin capacitance. To achieve this antenna/receiver capacitance match, it is important that the sense antenna be installed in accordance with the ADF manufacturer's recommendations for the particular make and model of aircraft.
d. Optimum ADF performance is achieved when the "T", rather than the "L", type of sense antenna is used, (see fig. 3.15). The "p" type has a noise cancelling effect due to the antenna cable being connected in the center of the antenna. The "L" type antenna has directional characteristics and may not produce a definite station passage indication as the "T" type does.
A whip antenna of a type and dimension recommended by the equipment manufacturer may be used in place of the "T" or "L' types. Methods of installing a whip antenna are shown in figures
3.1, 3.2, and 3.3.
e. Because the ADF receiver is susceptible to aircraft radiated noise, antenna lead-ins should be routed so that they are kept away from electric power cables, alternators, solid state power supplies, anti-collision lights, pulse transmitting equipment, etc. They may be rounted against airframe members for extra shielding.
f. Loop-ins should be of the recommended type and length. The length of lead-in specified by the manufacturer for a particular installation may be excessive for the physical dimensions between the antenna and receiver. Excessive leadin should not be trimmed, but should be coiled to take up the extra length. Do not coil excess cable in any area subject to electrical noise.
g. After completing the installation, it is essential that the loop be calibrated. One acceptable means of compliance is contained in AC 43.13-1A, chapter 15, section 6, paragraphs 848 through 853.
44. ANTENNA INSTALLATION ON PRESSURIZED AIRCRAFT. The use of doublers, to reinforce the aircraft skin to support antennas, is previously described in this chapter. The material contained in this paragraph concerns the methods of apply- Chap 3 21
AC 43.13-2A ing sealant to guard against the passage of air, liquids, and vapors from pressurized structures.
a. Typical Antenna Installation Procedure. When the attaching parts and the antenna are ready for installation, clean all faying surfaces with a cleaning solvent. Clean a larger area than that to which sealant is to be applied. Remove the solvent from the faying surfaces by blasting with dry air and wiping with a clean soft cloth.
(1) Coat the affected area with the primer specified by the sealant manufacturer.
(2) Apply the sealant to one surface, using a spatula or brush, and spread it over the entire faying surface until a uniform thickness of approximately ⅓2-inch is obtained. (See fig. 3.22 and 3.23.)
ANTENNA.
GASKET
SEALANT
AIRCRAFT SKIN - DOUBLER FIGURE 3.22. Typical antenna installation.
(3) Place the component parts together and install the required fasteners. If permanent fasteners cannot be installed, use temporary fasteners to hold the component parts together until the sealant has cured. Install permanent fasteners with fresh sealant by dipping the fastener in sealant or by filling the fastener hole with sealant. (See fig. 3.24.)
(4) Fill holes and joggles by injecting the sealant into the voids and/or cavities. This method is used where the sealant cannot be applied with a spatula or brush. Figure 3.25.
(5) Allow the sealant to cure, then remove excess sealant from the periphery of the antenna using a nonmetallic scraper.
22 Rev. 1977
•SEALANT APPROX.
1/32" THICK FIGURE 3.23.-Faying surface sealing.
Warning Sealants may contain toxic and/or flammable components. Avoid inhalation of vapors. Supply adequate ventilation and provide a suitable exhaust system. Wear approved respiratory protection while using these materials in confined areas. Do not allow the sealant to come in contact with the skin or eyes. Insure that no source of ignition is present in the working area.
b. High Speed Aircraft. The sealant methods described should be used to prevent moisture or water from entering the aircraft and the expulsion of air and vapors when the aircraft structure is pressurized.
SEALANT MAYBE
APPLIED EITHER TO
HOLE OR FASTENER
- SEALANT
- SEALANT FIGURE 3.24.-Fastener sealing.
Chap 3
Rev. 1977 AC 43.13-2A
(1) Figure 3.26 displays a blade type antenna mounted on a flat surface using a sealing gasket.
This type of installation does not require the application of a sealant.
(2) Figures 3.27 and 3.28 display two types of flush mounted antennas. The antenna unit and fiberglass cover are manufactured as one integral assembly.
(3) Flush mounted antennas installed on a vertical fin are normally part of the primary structure. The radiating elements of the antenna and the fiberglass cover are individual units.
GUN NOZZLE (a) Clean all metal surfaces necessary to insure good electrical bonding contact between the antenna mounting surface and the aircraft
(b) After the fiberglass cover is installed, FIGURE 3.25.-Injection sealing. sealer may be applied to fill the space between the fiberglass cover and skin of the vertical fin.
Figure 3.29 displays one-half of a vertical fin antenna installation. An identical installation is required on each side.
GASKET
ANTENNA FIOURE 3.27.-ATC flush mounted antenna.
FIGURE 3.26.- Blade antenna installation.
Chap 3 23
AC 43.13-2A Rev. 1977
• FIGURE 3.28.-Marker beacon flush mounted antenna.
FIGURE 3.29.-VOR flush mounted antenna.
45.-50. [RESERVED] 24 Chap 3 |
Rev. 1977 AC 43.13-2A Chapter 4. ANTICOLLISION AND SUPPLEMENTARY LIGHT INSTALLATIONS
51. ANTICOLLISION AND SUPPLEMENTARY LIGHT SYSTEMS.
a. Anticollision Lights. The requirements for anticollision lights are included in Federal Aviation Regulations, Parts 23, 25, 27, and 29. Aircraft for which an application for type certificate was made before April 1, 1957, may conform either to the above regulations or to the following
(1) Anticollision lights (when installed) should be installed on top of the fuselage or tail in such a location that the light will not be detrimental to the flight crew's vision and will not detract from the conspicuity of the position lights.
If there is no acceptable location on top of the fuselage or tail, a bottom fuselage installation may be used.
(2) The color of the anticollision light shall be aviation red or white in accordance with the specifications of FAR Part 23.
(3) The arrangement of the anticollision light
(i.e., number of light sources, beam width, speed of rotation, etc.) should be such as to give an effective flash frequency of not less than 40 and not more than 100 cycles per minute.
b. Supplementary lights may be installed in addition to position and anticollision lights required by applicable regulations, provided that the required position and anticollision lights are continuously visible and unmistakably recognizable and their conspicuity is not degraded by such supplementary lights.
52. INTERFERENCE.
a. Crew Vision. Partial masking of the light may be necessary to prevent direct or reflected light rays from any anticollision or supplementary light from interfering with crew vision.
Determine that the field of coverage requirements are met. An acceptable method of preventing light reflection from propeller disc, nacelle, or wing surface is an application of nonreflective paint on surfaces which present a reflection problem. Perform a night flight-check to assure that any objectionable light reflection has been eliminated. Enter a notation to that effect in the aircraft records.
b. Communication and Navigation. Assure that the installation and operation of any anticollision/supplementary light does not interfere with the performance of installed communication or navigation equipment. Capacitor discharge light (strobe) systems may generate radio frequency interference (RFI). This radiated interference can be induced into the audio circuits of communication or navigation systems and is noticeable by audible clicks in the speaker or headphones. The magnitude of the RFI disturbance does not usually disrupt the intelligence of audio reception.
c. Precautions. RFI can be reduced or eliminated by observing the following precautions during installation of capacitor discharge light systems :
(1) Locate the power supply at least three
(3) feet from any antenna, especially antennas for radio systems that operate in the lower frequency bands.
(2) Assure that the lamp unit (flash tube) wires are separated from other aircraft wiring placing particular emphasis on coaxial cables and radio equipment input power wires.
(3) Make sure that the power supply case is adequately bonded to the airframe.
(4) Ground the shield around the interconnecting wires between the lamp unit and power supply at the power supply end only.
53. MARKINGS AND PLACARDS. Identify each switch for an anticollision/supplementary light and indicate its operation. The aircraft should be flight tested under haze, overcast, and visible Chap 4 25
AC 43.13-2A moisture conditions to ascertain that no interference to pilot vision is produced by operation of these lights. If found unsatisfactory by test, or in the absence of such testing, a placard should be provided to the pilot stating that the appropriate lights be turned off while operating in these conditions.
54. ELECTRICAL INSTALLATION. Install an individual switch for the anticollision light or supplementary light system that is independent of the position light system switch. Data for the installation of wiring, protection device, and generator limitations is contained in chapter 11 of Advisory Circular 43.13-1A, "Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair." Assure that the terminal voltage at each light is within the limits as prescribed by the manufacturer.
55. ALTERATION OF STRUCTURE.
a. The simplest light installation is to secure the light to a reinforced fuselage skin panel.
The reinforcement doubler shall be of equivalent thickness, material, and strength as the existing skin. (Install as shown in fig. 4.1.)
ANTICOLLISION LIGHT OR
SUPPLEMENTARY LIGHT
FUSELAGE SKIN
- EXISTING STRINGER
EXISTING STRINGER VIEW A-A
APPROXIMATELY ONE REINFORCING DOUBLER INCH SPACING OF ALCLAD 2024-73 1/8" MIN. DIA. RIVET 1 1/2" EDGE DISTANCE MIN.
FIGURE 4.1.- -Typical anticollision or supplementary light installation in a skin panel (unpressurized).
Rev. 1977
b. When a formed angle stringer is cut and partially removed, position the reinforcement doubler between the skin and the frame. Doubler to be equivalent to the stringer in thickness and extend lengthwise beyond the adjacent fuselage frames. The distance between the light and the edge of the doubler is twice the height of the doubler flange. (See fig. 4.2 for typical installation.)
CUT STRINGER EINFORCING DOULLE ANTICOLLISION LIGHT OR * ALCLAD T.
SUPPLEMENTARY LIGHT FRAME
STRINGER
DOUBLE FLANGES
AT LEAST THE HEIGHT STRINGER
OF CUT STRINGER STUNGER RIVETS ADDED
FLANGE AND DOULLER AS SHOWN ON
EXISTING RIVETS FRAMES FIGURE 4.2.-Typical anticollision or supplementary light installation involving a cut stringer (unpressurized).
c. Engineering evaluation is required for instal lations involving the cutting of complex formed or extruded stiffeners, fuselage frames, or pressurized skin of pressurized aircraft.
d. Vertical stabilizer installations may be made on aircraft if the stabilizer is large enough in cross section to accommodate the light installation, and aircraft flutter and vibration characteristics are not adversely affected. Locate such an installation near a spar, and add formers as required to stiffen the structure near the light.
(A typical installation is shown in fig. 4.3.)
e. Rudder installations are not recommended because of the possible structural difficulties.
However, if such installations are considered, make an engineering evaluation to determine whether the added mass of the light installation Chap 4
Rev. 1977
MOUNTING SCREW HOLES
FOR LIGHT TO FAIRING
ANTICOLUSION LIGHT O
SUPPLEMENTARY LIGH
VERTICAL
STABILIZER
APPROXIMATELY ONE
INCH SPACING OF 1/8" MIN. DIA. RIVET
LIGHT MOUNTING
FAIRING
• MOUNTING RING
VERTICAL
STABILIZER
VIEW A-A NOTE:
SKIN THICKNESS OF MOUNTING RING AND
FAIRING ARE AT LEAST EQUIVALENT FIGURE 4.3.-Typical anticollision or supplementary light installation in a fin tip.
will adversely affect the flutter and vibration characteristics of the tail surfaces.
f. Pressurized Aircraft Installation. Doubler installation to reinforce the aircraft skin previously described in this chapter is adaptable to pressurized structure with the application of sealant.
Sealant is used to prevent moisture or water from entering the aircraft and the expulsion of air when the aircraft structure is pressurized.
(1) Sealant procedures for aircraft skin reinforcing doubler and doubler fasteners are contained in paragraph 44, chapter 3 of this manual.
The aircraft manufacturer's data may recommend the specific sealant to be used and provide instructions for the application.
(2) Figures 4.4 and 4.5 illustrate two different designs of anticollision light assemblies.
The application of sealant is required when either type of light assemblies is installed.
procedures would be identical for installation of a capacitor discharge (strobe) light system.
Chap 4 AC 43.13-2A
AIRCRAFT SKIN
DOUBLER -
SEALANT FIGURE 4.4.-Typical rotating type anticollision light installation for pressurized aircraft.
Caution: Sealant and solvents may contain toxic and/or flammable components. Avoid inhalation of vapors and supply adequate ventilation. Wear appropriate respiratory protection while using these materials in confined areas. Avoid contact with the skin and eyes.
AIRCRAFT SKIN
DOUBLER
SEALANT
COAT SCREWS WITH SEALANT FIGURE 4.5.-Typical oscillating type anticollision light installation for pressurized aircraft.
56. GUIDELINES FOR INSTALLATIONS.
a. Prior Approval. Due to the complexity of measurements for intensity, field of coverage, and color, evidence of FAA approval should be obtained from the light manufacturer before installation.
b. System Performance.
(1) Field of Coverage. Evidence of FAA approval for "field of coverage" should be obtained from the light manufacturer before installation. To insure that the manufacturer's approved field of coverage is applicable to an installation, his mounting tolerance should not be exceeded.