Rev. 1977 AC 43.13-2A
CONTENTS Chapter 1. STRUCTURAL DATA Paragraph Page
1. General -
2. Static Loads -. ....
3. Static Tests
4. Materials --.
5. Fabrication
6. Fasteners --
7. Protection Against Deterioration
8. Provisions for Inspection --
9. Effects on Weight and Balance
10. Effects on Safe Operation -.
11. Controls and Indicators --
12. Placarding
18.-20. [Reserved] Chapter 2. RADIO INSTALLATIONS
21. Installation
22. Equipment Manufacturer's Instructions
23. Instrument Panel Mounting
24. Other Mounting Areas --
25. Fabrication of Supporting Brackets for Attachment to Structure Other Than Flooring -
26. Supporting Structure Reinforcement
27. Electrical Systems
28. Emergency Locator Transmitter (ELT) Installations
29.-35. [Reserved] Chapter 3. ANTENNA INSTALLATIONS
36. Performance
37. VHF Antenna-Whip
38. VHF Antenna-Rigid -
39. VHF Navigation Receiving Antennas
40. Range Receiving Antennas -
41. Marker Receiving Antenna -
42. ATC Radar Beacon (Transponder) and Distance Measuring Equipment (DME) Antennas -
43. Direction Finding Antennas
44. Antenna Installation on Pressurized Aircraft
45.-50. [Reserved] 24 Chapter 4. ANTICOLLISION AND SUPPLEMENTARY LIGHT INSTALLATIONS
51. Anticollision and Supplementary Light Systems 25
52. Interference
53. Markings and Placards
54. Electrical Installation -
55. Alteration of Structure
56. Guidelines for Installations -
57.-60. [Reserved]
AC 43.13-2A Rev. 1977 CONTENTS-Continued Chapter 5. SKI INSTALLATIONS Paragraph Section 1. SELECTION OF SKIS Page
61. Determining Eligibility of Aircraft 33
62. Identification of Approved Model Skis
63. Maximum Limit Load Rating
64. Landing Gear Moment Reactions 34
65. [Reserved] - 34 Section 2. CONVERSION AND INSTALLATION
66. Hub-Axle Clearance --. 35
67. Crust-Cutter Cables ------ 35
68. Cable and Shock Cord Attachment and Attachment Fittings - 35
69. Provisions for Inspection -. 36
70. [Reserved] 36 Section 3. RIGGING OF SKIS
71. Location of Attach Fittings on Fuselage or Landing Gear
72. Main Ski Incidence Angles
73. Tension Required in Main Ski Shock Cords
74. Nose Ski Installation -
75. Tail Ski Installation
76.-78. [Reserved] 40 Section 4. OPERATION
79. Performance Information -
80. Flight and Handling Operational Checks
81. Interchanging of Skis and Wheels
82.-85. [Reserved] Chapter 6. OXYGEN SYSTEM INSTALLATIONS IN NONPRESSURIZED AIRCRAFT
86. System Requirements --- 43
87. Installation 43
88. Location and Mounting - 41
89. Thread Compound
90. Functional Test -
91. Operating Instructions 46
92.-95. [Reserved] 47 Chapter 7. ROTORCRAFT EXTERNAL-LOAD DEVICE INSTALLATIONS Section 1. CARGO SLINGS
96. General --
97. Quick-Release Device
98. Location of Cargo Release in Relation to the Rotorcraft's C. G. Limits
99. Maximum External Load
100. Static Test
101. Sling-Leg Angles of Cable-Supported Slings 102. Minimum Sling-Leg Cable Strength 50
103. Sling Installation 50
104. Installation of Release Controls 51 52
105. Functional Test --
106. Supplemental Flight Information 52
107.-110. [Reserved] 53 Section 2. CARGO RACKS
111. General
112. Fabrication of Cargo Racks
113. Static Test ------
114. Supplemental Flight Information
115.-120. [Reserved]
CONTENTS-Continued Chapter 8. GLIDER AND BANNER TOW-HITCH INSTALLATIONS Paragraph Section 1. TOWPLANE CONSIDERATIONS Page * 121.-125. [Deleted] Change 1 57 Section 2. TOW-HITCH INSTALLATIONS
126. Structural Requirements. 58
127. Structural Testing 59
128. Attachment Points _ 59
129. Angies of Tow .. 59
130. Placards. 59
131. Weight and Balance 59
132. Tow Release Mechanism _ 59 * 133. [Deleted] Change 1 60
134.-145 [Reserved] _ 63 Chapter 9. SHOULDER HARNESS INSTALLATIONS Section 1. RESTRAINT SYSTEMS
146. General 65
147. Types of Restraint Systems
148. Advantages of Different Harness Types
149. Mounting Configurations ...
150. Standards
151. Materials
152.-155. [Reserved] _ Section 2. EFFECTIVE RESTRAINT ANGLES
156. Relationship of the Harness Assembly to the Occupant .
157. Attachment Areas for Shoulder Harness
158. Area and Angle Deviations -
159.-160. [Reserved] __.
Section 3. ATTACHMENT METHODS
161. Structural Attachments
162. Floor and Seat Attachments
163. Airframe Attachments _
164. Structural Repair Kits_.
165. Flexible Attachments
166. Simplified Installation Criteria
167. Engineering Approval
168.-175. [Reserved].
Chapter 10. BATTERY INSTALLATIONS Section 1. GENERAL
176. General
177. Location Requirements
178. Duplication of the Manufacturer's Installation
179. Other Installations .
180.-185. [Reserved] 78 Section 2. INSTALLATION
186. Securing the Battery 79
187. Venting-_ 79
188. Drains .. 79
189. Electrical Installation 80
190.-195. [Reserved] _ 80 III
AC 43.13-2A Rev. 1977 CONTENTS-Continued Paragraph Page Section 3. REPLACEMENT OF LEAD-ACID BATTERIES WITH NICKEL-CADMIUM BATTERIES
196. General 81
197. Electrical Analysis ào 00
198. Maintenance Considerations
199. Structural Requirements --- 81
200. Isolation of Battery Case -- 81
201. Ventilation 82
202. Preinstallation Requirements 82
203. Securing The Battery 83
204. Voltage and Current Regulation 83
205. Weight and Balance --- 83
206. Restoration of Lead-Acid Batteries 83
207.-210. [Reserved] 83 Chapter 11. ADDING OR RELOCATING INSTRUMENTS
211. General
212. Preparation
213. Installation
214. Testing, Marking and Placarding
215.-240. [Reserved] Chapter 12. LITTER, BERTH, AND CARGO TIEDOWN DEVICE INSTALLATIONS
241. General 89
242. Installation Considerations -
243. Fabrication and Installation
244. Structural Attachment
245. Load Factors 95
246. Static Tests
247. Operating Limitations, Loading Instructions, and Placards
248.-260. [Reserved] Chapter 13. PENETRATION THROUGH PRESSURIZED STRUCTURE Section 1. ELECTRICAL WIRE BUNDLES AND COAXIAL CABLE FEED THROUGH PRESSURIZED STRUCTURE
261. General 97
262. Cleaning
263. Application of Sealant
264.-290. [Reserved] 97
LIST OF ILLUSTRATIONS Figure Page
1.1 Hypothetical Example of Determining Static Test Loads
2.1 Typical Radio Installations in Stationary Instrument Panels
2.2 Typical Panel Mount
2.3 Typical Shockmounted Base --.
2.4 Typical Shockmounted Base ---
2.5 Typical Rigid Baseplate Mount
2.6 Typical Underseat Installation
2.7 Typical Remote Unit Mounting Base-Vertical or Horizontal
2.8 Typical Shelf Installation
2.9 Typical Rail Platform Installation-Aluminum Alloy Structure -
2.10 Typical Attachment of Support Structure to Tubular Frame --.
2.11 Typical Mounting Plates for Remote Location of Radio Units
3.1 Typical Whip Antenna Installation IV
Rev. 1977 AC 43.13-2A CONTENTS-Continued LIST OF ILLUSTRATIONS Continued Figure Page
3.2 Antenna Ground Plane for Nonmetallic Aircraft 14
3.3 Typical Shockmounted Antenna Installation
3.4 Typical Rigid Antennas _.
3.5 Typical Antenna Mounting Template 15
3.6 Typical Antenna Installation on a Skin Panel 15
3.7 Preferred VOR Antenna Location for Maximum Signal Pickup With Minimum Ignition Interference -- 16
3.8 Typical Antenna Installation Involving a Cut Stringer 16
3.9 Typical Dipole Antenna Assembly 16
3.10 Typical VOR Antenna Balun --
3.11 Coaxial Cable Preparation --
3.12 Coaxial Cable Tinning Center Lead -
3.13 Coaxial Cable Soldering Center Lead
3.14 Coaxial Cable Install Connector Body
3.15 Typical Wire Antenna Locations
3.16 Typical Marker Beacon Receiving Antenna 18
3.17 Typical Wing Tip Installations 19
3.18 Typical Fin Tip Installations - 19
3.19 Typical Wire Antenna Installations 20
3.20 Preferred Position for Distance Measuring Antennas and/or ATC Radar Beacon Antennas 20
3.21 Typical ADF Antenna Installations 21
3.22 Typical Antenna Installation --- 22
3.23 Faying Surface Sealing 22
3.24 Fastener Sealing 22
3.25 Injection Sealing 23
3.26 Blade Antenna Installation 23
3.27 ATC Flush Mounted Antenna -- 23
3.28 Marker Beacon Flush Mounted Antenna 24
3.29 VOR Flush Mounted Antenna -- 24
4.1 Typical Anticollision or Supplementary Light Installation in a Skin Panel (Unpressurized) -. 26
4.2 Typical Anticollision or Supplementary Light Installation Involving a Cut Stringer (Unpressurized) ---- 26
4.3 Typical Anticollision or Supplementary Light Installation in a Fin Tip 27
4.4 Typical Rotating Type Anticollision Light Installation for Pressurized Aircrait 27
4.5 Typical Oscillating Type Anticollision Light Installation for Pressurized Aircraft _-
4.6 Ramp Shadow Pattern
4.7 Conversion to Vertical vs. Horizontal Degrees
4.8 Conversion to True Square Degrees-1st Quadrant
4.9 Scale Drawings _
4.10 Solid Angle Blockage1st Quadrant 31
5.1 Typical Ski Installation -- 33
5.2 Typical Hub Installation 35
5.3 Typical Fuselage Fitting 36
5.4 Main Ski at Maximum Positive Incidence (Check Cable Tight) - 37
5.5 Main Ski at Maximum Negative Incidence (Safety Cable Tight) 38
5.6 Main Ski Incidence Angles - 38
5.7 Typical Nose Ski Installation -- 39
5.8 Typical Tail Ski Installation --. 40
6.1 Typical Oxygen Duration Table .
6.2 Typical Floor Mounting -------
6.3 Typical Baggage Compartment Mounting 46
AC 43.13-2A, CHG. 1 6/1/79 CONTENTS-Continued LIST OF ILLUSTRATIONS-Continued Page Typical Oxygen Installation in Light Twin Aircraft_. 47 Location of Cargo Release in Relation to the Rotorcraft's Center of Gravity 49 Cable Load Table _ 50 Typical Cargo Sling Wiring Diagram - 51 Typical Cargo Sling Installation No. 1 52 Typical Cargo Sling Installation No. 1 (Showing Fuselage Attachment 52 Treas Cargo sling Installation No. 1 (Showing Fore and Aft Limiting 52
7.7 Typical Cargo Sling Installation No. 2 (Cargo Hook Attached Directly to Underside of Fuselage). 52 Typical Cargo Sling Installation No. 3(4-leg, Cable Suspended). 53 Typical Cargo Sling Installation No. 3 (Showing Cable Sling Leg Attachment to Landing Gear Cross-Tube Fitting) 53
7.10 Typical Cargo Sling Installation No. 3 (Showing Cargo Sling in Stowed 53
7.11 Typical Cargo Rack Installation No. 1 54
7.12 Typical Cargo Rack Installation No. 1 (Showing Attachment Detail) - 54
7.13 Typical Cargo Rack Installation No. 2 - 55
7.14 Typical Cargo Rack Installation No. 2 (Showing Rack Partially Installed) 55
7.15 Typical Cargo Rack Installation No. 3 - 55 Glider Tow Angle 58
8.2 Banner Tow Angle 58
8.3 Typical Tow-Hitch Release Handle 59
8.4 Representative Steel Cable Qualities. 60 * 8.5 [Deleted] Change 1 - 60
8.6 Tricycle Gear Aircraft 62
8.7 Conventional Gear Aircraft-Leaf Spring Type Tail wheel 62
8.8 Conventional Gear Aircraft-Shock Strut Type Tailwheel 63
8.9 Conventional Gear Aircraft-Tubular Spring Type Tailwheel 63
9.1 Single Diagonal Type Harness _ 66
9.2 Double Over-the-Shoulder Type Harness 66
9.3 Side Mounted-Single Diagonal Type Harness.. 67
9.4 Ceiling Mounted Inertia Reel-Single Diagonal Type Harness 68
9.5 Acceptable Mounting Area-Single Diagonal Type Harness 69
9.6 Ceiling Mounted Inertia Reel-Double Over-the-Shoulder Type Harness - 69
9.7 Acceptable Mounting Areas- Double Over-the-Shoulder Type Harness 69
9.8 Floor Mounted Inertia Reel-Double Over-the-Shoulder Type Harness 71
9.9 Typical Floor Mounted Inertia Reel Installation. 72
9.10 Typical Seat Mounted Inertia Reel Installation 72
9.11 Typical Bulkhead Reinforcement Installation 73
9.12 Typical Wing Carry-Through Member Installation. 73
9.13 Typical Hat Section Reinforcement Installation. 74
9.14 Typical Stringer Section Reinforcement Installation 74
9.15 Typical Stringer Section Reinforcement Installation 74
9.16 Typical Attachment to Tubular Members - 75 Typical Battery Box Installation in Aft Fuselage Area... 77 Typical Battery Box Installation in Aft Fuselage Area, Below Cabin Floorboards .. 77
10.3 Typical Battery Box Installation in Aft Fuselage Area
10.4 Typical Battery Box Installation Suspended From Cabin Floorboard Section
10.5 Battery with Integral Vent Nipples _
10.6 Typical Battery Cutoff and Generator/Alternator Control Circuit
10.7 Change in Cantilever Support Battery Overhang Moment.
11.1 Pressure Drop Data for Smooth Tubing VI
Rev. 1977 AC 43.13-2A CONTENTS-Continued LIST OF ILLUSTRATIONS- Continued Figure Page
12.1 Extruded Track, Anchor Plates, and Associated Fittings 90
12.2 Miscellaneous Litter, Berth, and Cargo Tiedown Fittings 91
12.3 Typical Attachment of Fittings to Honeycomb Structures 92
12.4 Installation of Underfloor Support for Extruded Track - 93
12.5 Typical Cargo Tiedown Straps and Cargo Nets - 94
13.1 Sealant Application 98
13.2 Fair-lead Feed Through 99
13.3 Typical Connector 99
13.4 Coaxial Connectors 100
LIST OF TABLES Table Page
11.1 Instrument Air Consumption ------------- 86
11.2 Equivalent Straight Tube Line Drops for 90° Elbows ------------------- 86
11.3 Differential Pressure Across Instrument Inlet and Outlet --------------- 86 VII
Rev. 1977 AC 43.13-2A Chapter 1. STRUCTURAL DATA
1. GENERAL. The minimum airworthiness requirements are those under which the aircraft was type certificated. Addition or removal of equipment involving changes in weight could affect the structural integrity, weight, balance, flight characteristics, or performance of ** Due to differences among various aircraft designs in flight and ground load factors, contact the aircraft manufacturer for the load factors required for a given model and location. In lieu of specific information, the factors used for FAR 23 utility category are acceptable for aircraft with never exceed speed of 250 knots or less and the factors used for FAR 23 acrobatic category for all other transport aircraft.
2. STATIC LOADS. Utilize equipment supporting The following is an example of determining structure and attachments that are capable of the static test loads for a 7-pound piece of equipwithstanding the additional inertia forces ("g." ment to be installed in a utility category alrload factors) imposed by weight of equipment craft (FAR Part 23).
installed. Load factors are defined as follows:
a. Limit Load Factors are the maximum load Load Factors Static Test Loads factors which may be expected during service (From the above table) (Load factor × 7 pounds) (the maneuvering, gust, or ground load factors Sideward 1.5g 10.5 pounds established by the manufacturer for type cer- Upward Downward 6.6g 3.0g 21.0 pounds 46.2 pounds tification). Forward 9.0g 63.0 pounds
b. Ultimate Load Factors are the limit load factors multiplied by a prescribed factor of safety. Certain loads, such as the minimum ultimate inertia forces prescribed for emergency landing conditions, are given directly in terms of ultimate loads.
When an additional load is to be added to structure already supporting previously installed equipment, determine the capability of the structure to support the total load (previous load plus added load).
c. Static Test Load Factors are the ultimate load 3. STATIC TESTS.
factors multiplied by prescribed casting, fitting, Caution: The aircraft and/or equipment can bearing, and/or other special factors. Where no be damaged in applying static loads, particularly special factors apply, the static test load factors if careless or improper procedure is used.
direction (up, down, side, fore, and aft). greater of the maneuvering, gust, ground, and inertia load static test load factors for each are equal to the ultimate load factors. d. Critical Static Test Load Factors are the related aircraft structure. Static test loads may exceed the yield limits of the assemblies being It is recommended, whenever practicable, that static testing be conducted on a duplicate installa- tion in a jig or mockup which simulates the Static tests using the following load factors are substantiated and can result in partially sheared acceptable for equipment installations: fasteners, elongated holes, or other damage which Normal- may not be visible unless the structure is dis- Direction of Utility Acrobatic Transport • Rotorcraft assembled. If the structure is materially weak- Force Applied (CAR 3) FAR 23 (CAR 3) PAR 23 (CAR 4b) FAR 25 FAR 27, 29 (CAR 6, 7) ened during testing, it may fail at a later date.
Sideward 1.5g 1.5g 1.5g 2.0g Riveted sheet metal and composite laminate con- Upward 3.0g 4.5g 1.5g struction methods especially do not lend them- Forward* Downward 9.0g 6.6g 9.0g 9.0g 9.0g 4.0g 4.0g selves to easy detection of such damage. To conduct static tests:
* When equipment mounting is located externally to one side, or forward of occupants, a forward load factor a. Determine the weight and center of gravity of 2.0g is sufficient. position of the equipment item.
Chap 1
AC 43.13-2A
b. Make actual or simulated installation of attachment in the aircraft or preferably on a jig using the applicable static test load factors.
c. Determine the critical ultimate load factors for the up, down, side, fore, and aft directions.
A hypothetical example which follows steps (1) through (4) below is shown in figure 1.1.
(1) Convert the gust, maneuvering, and ground load factors obtained from the manufacturer or FAA engineering to ultimate load factors. Unless otherwise specified in the airworthiness standards applicable to the aircraft, ultimate load factors are limit load factors multiplied by a 1.5 safety factor. (See columns 1, 2, and 3 for items A, B, and C of fig. 1.1.)
(2) Determine the ultimate inertia load forces for the emergency landing conditions as prescribed in the applicable airworthiness standards. (See items D and E, column 3, of fig. 1.1.)
(3) Determine what additional load factors are applicable to the specific seat, litter, berth, or cargo tiedown device installation. The ultimate load factors are then multiplied by these factors to obtain the static test factors. (To simplify this example, only the seat, litter, berth, and safety belt attachment factor of
1.33 was assumed to be applicable. See Item E, column 4, of fig. 1.1.)
(4) Select the highest static test load factors obtained in Steps 1, 2, and/or 3 for each direction (up, down, side, fore, and aft). These factors are the critical static test load factors used to compute the static test load. (See column 6 of fig. 1.1.)
d. Apply load at center of gravity position (of equipment item or dummy) by any suitable means that will demonstrate that the attachment and structure are capable of supporting the required loads.
When no damage or permanent deformation occurs after 3 seconds of applied static load, the structure and attachments are acceptable. Should permanent deformation occur after 3 seconds, repair or replace the deformed structure to return it to its normal configuration and strength. Additional load testing is not necessary.
Rev. 1977
4. MATERIALS. Use materials conforming to an accepted standard such as AN, NAS, TSO, or MIL-SPEC.
5. FABRICATION. When a fabrication process which requires close control is used, employ methods which produce consistently sound structure that is compatible with the aircraft structure.
6. FASTENERS. Use hardware conforming to an accepted standard such as AN, NAS, TSO, or MIL-SPEC. Attach equipment so as to prevent loosening in service due to vibration.
7. PROTECTION AGAINST DETERIORATION. Provide protection against deterioration or loss of strength due to corrosion, abrasion, electrolytic action, or other causes.
8. PROVISIONS FOR INSPECTION. Provide adequate provisions to permit close examination of equipment or adjacent parts of the aircraft that regularly require inspection, adjustment, lubrication, etc.
9. EFFECTS ON WEIGHT AND BALANCE. Assure that the altered aircraft can be operated within the weight and center of gravity ranges listed in the FAA Type Certificate (T.C.) Data Sheet or Aircraft Listing. Determine that the altered aircraft will not exceed maximum gross weight.
(If applicable, correct the loading schedule to reflect the current loading procedure.) Consult Advisory Circular 43.13-1A, Acceptable Methods, Techniques, and Practices--Aircraft Inspection and Repairi for Weight and Balance Computation Procedures.
10. EFFECTS ON SAFE OPERATION. Install equipment in a manner that will not interfere with or adversely affect the safe operation of the aircraft (controls, navigation equipment operation, etc.).
11. CONTROLS AND INDICATORS. Locate and identify equipment controls and indicators so they can be operated and read from the appropriate crewmember position.
12. PLACARDING. Label equipment requiring identification and, if necessary, placard operational instructions. Amend weight and balance information as required.
13.-20. [RESERVED] Chap 1
AC 43.13-2A Static Test 9.3g 5.7g *9. 6g 2. 4g 9. 9g **4.5g 12. 0g Static = Test 9.3g 5.7g 1. 5g 9. 0g 9.6g 4. 2g 9. 9g 6. 0g 1.5g - 3. 0g 12. 0g 2. 0g - 4. 0g LOAD FACTORS X Special — Ultimate 9.30g 5.7g 1. 5g 9. 0g 9. 6g 2. 4g 4. 2g 9. 9g 6. 0g 9. 0g 4. 5g (None) 1. 5g - 3. 0g (None) 1.33 9. 0g (None) 1.33 1. 5g 1.33 - 3. 0g (None) FIGURE 1.1-Hypothetical example of determining static test loads.
Utility Category Aircraft (FAR 23) X Safety 1.5 1.5 1.5 1.5 1.5 1. 5 1.5 1.5 1.5 Already Prescribed as Ultimate Limit (None) 6. 2g (None) - 3.8g 1. 0g (None) 6. 0g 6. 4g 1. 6g - 2. 8g (None) 6. 6g 4. 0g *Asterisks denote special load conditions for the situation shown.
Direction Fwd_ Down Side- Up-- Aft... Fwd. Down. Down* 'Side_ Up_. Aft_. Fwd. Down Fwd. Fwd.** Down. Side. Up_ Aft_ Fwd Down Side Up_ Aft _ TYPE OF LOAD Maneuvering. Gust (— 30 FPS @ KVc) *For locations aft of fuselage Sta. 73.85. Ground_ Ultimate Inertia Forces for Emer- gency Landing Condition (FAR 23.561). **For Separate cargo compartments. Ultimate Inertia Forces for Emer- gency Landing Condition For Seat, Litter, & Berth Attachment to Air- craft Structure (FAR 23.785).
E.
Chap 1
Rev. 1977 AC 43.13-2A Chapter 2. RADIO INSTALLATIONS
21. INSTALLATION. When installing radio equipment, first consider areas or locations designated by the airframe manufacturer and use factory supplied brackets or racks. Follow the aircraft manufacturer's installation instructions. When this information is not available, use locations in the aircraft of known load carrying capabilities. Baggage compartments and cabins or cockpit floors are good mounting platforms providing the floor attachments meet the strength requirements. Another method is to fabricate support racks, brackets, or shelves, and attach them to the aircraft structure to provide a mounting that will withstand the inertia forces stipulated in chapter 1 of this handbook.
a. Determine that the location and installation of radio equipment provides:
(1) Sufficient air circulation to avoid overheating.
(2) Sufficient clearance between high temperature areas of equipment and readily flammable
(3) Protection from potentially hazardous fluids and/or fumes; e.g., water (condensation), fuel, hydraulic fluid, or oxygen units.
(4) Protection against damage from baggage or by seat deflection.
(5) Sufficient clearance to avoid equipment striking adjacent parts of the aircraft or other equipment.
(6) Minimum interference to other installed navigational equipment from the emission of radar/pulse frequencies or from electromagnetic and is applicable to the installation of radio units in instrument panels.
a. Stationary Instrument Panels-Nonstructural and Structural. The stationary instrument panel in some aircraft is primary structure. Prior to making any additional "cutouts" or enlargement of an existing "cutout" determine if the panel is primary structure.
tural, make additional "cutouts" or the enlargement of existing "cutouts" in accordance with the aircraft manufacturer's instructions, or substantiate the structural integrity of the altered panel in a manner acceptable to the Administrator. Radius all corners and remove all burrs from "cutout" and drilled holes.
b. Added Equipment - Stationary Instrument Panel. When radio equipment is to be installed in a stationary panel already supporting instruments, glove compartments, etc., determine the capability of the panel to support the total load.
c. Case Support. To minimize the load on a stationary instrument panel, whenever practicable, install a support between the rear (or side) surface of the radio case and a nearby structural member of the aircraft.
d. Added Equipment-Shockmounted Panels.
When installing radio equipment designed for use in shockmounted panels, total accumulated weight of equipment installed must not exceed the weight carrying capabilities of the shockmounts. Determine that the structure to which the shockmounts are connected is satisfactory for the added weight.
22. EQUIPMENT MANUFACTURER'S INSTRUC- TIONS. Installation instructions provided by the aircraft radio manufacturer are acceptable guidelines when adapted to the aircraft in accordance with data contained in this chapter.
23. INSTRUMENT PANEL MOUNTING. Data in this paragraph is supplemented by chapter 2 of AC 43.13-1A, 'Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair"
e. Existing Factory Fasteners. When possible, utilize existing plate nuts and machine screws provided by the aircraft manufacturer for attachment of the radio case or rack. If additional fastening is required, use machine screws and elastic stop nuts (preferably plate nuts).
f. Magnetic Direction Indicator. As a function of the radio installation, determine if it is necessary to compensate the compass. Install a suitable placard which indicates the compass error Chap 2
AC 43.13-2A Rev. 1977 with the radios) on and off. The receiver (s) should be tuned through the low, middle and higher frequencies to cover all contingencies involving the operation of relays which would cause electromagnetic induction to the magnetic compass. When inverters are installed, deter- Typical Compass Calibration Card FOR N 30 60 120 150 mine what effect their operation has on the mag.
netic compass. Maximum acceptable deviation in level flight is 10° on any heading. The following is an example of a typical compass calibration card.
24. OTHER MOUNTING AREAS. The following are acceptable methods for installing radio equipment at other than instrument panel locations.
a. Shockmounted Units.
Radio On. (1) Wood or Composition Flooring. Secure the Steer 4° 35° 63° 93° 123° 154° shockmounted base assembly (suitable to radio Radio Off. unit) directly to the floor using machine screws.
Steer 358° 27° 58° 88° 118° | 148° Add a doubler to the bottom of the floor thereby sandwiching the composition floor between each FOR S 210 240 300 330 shockmount foot and the doubler. Subsequent removal and reinstallation of the shockmount Radio On. foot will be facilitated if plate nuts are secured Steer 183° 214° 224° 274° 304° 337° to the doubler. Where practicable, use small Radio Off.
Steer 178° 208° 238° 268° 293° 327° retaining screws to keep the doubler in position.
Install a ground strap between the radio rack and metal structure of the aircraft.
Typical Locations of Rodio Equipment FIGURE 2.1.-Typical radio installations in stationary instrument panels.
3.0g (up) Wood
1.5g (side) Flooring MACHINE SCREW
NORMAL-UTILITY
CATEGORY
2.0 (fwd) 6.6g (down) Doubler 4 Plate Nur FIGURE 2.3.--Typical shockmounted base.
Machine screws and self-locking nuts. (2) Metal Flooring. Secure the shockmounted base assembly directly to the floor using machine screws, washers, and self-locking nuts. Floor area under and around the radio mounting bases may require installation of doublers or other reinforcement to prevent flexing and cracking.
Installation of plate nuts on the floor or doubler Rivets or Machine screws will facilitate removal and installation of the and self-locking nuts. shockmounts. Install a ground strap between FIGURE 2.2.-Typical panel mount. the shockmount foot and the radio rack.
Chap 2