Par 11-260 Page 11-584
SECTION 19. PROTECTION OF UNUSED CONNECTORS
GENERAL. Connectors may have one or more contact cavities that are not used. Depending on the connector installation, unused connector contact cavities may need to be properly sealed to avoid damage to the connector, or have string wire installed.
QUICK REFERENCE CHART. A quick reference chart of unused connector contact cavity requirements is given in table 11-25. These requirements apply to harness manufacturing or connector replacement only.
UNPRESSURIZED AREA CONNECTORS.
Connectors may be installed in unpressurized areas of the aircraft. Unused connector contact cavities installed in unpressurized areas should be properly sealed as follows:
Firewall Connectors Installations. Firewall unused connector contact cavities should be filled with spare contacts and stub wires. (See figure 11-39.)
Construct stub wires using high temperature wire (260 ºC). Ensure that stub wires are of the same type of wires in the bundle.
Crimp the proper contact, for the connector and cavity being used, onto the wire. Install the crimped contact into the unused cavity.
Extend stub wires beyond the back of the connector clamp from 1.5 to 6 inches. Feather trim stub wires to taper wire bundle.
Secure wire ends with high temperature (greater than 250 ºC) lacing cord. Nylon cable ties are not allowed for this installation.
NOTE: Both connectors mating through the engine fire-seal are considered firewall connectors. Connectors mounted on or near, but not through, the engine fire-seal are not considered firewall connectors
Non-firewall Connector Installations. In this type of installation all unused connector cavities must also be filled with spare contacts. It is not required, however, to crimp stub wires on filling contacts.
Fill unused contact cavities with spare contacts and Teflon sealing plugs or rods. (See figure 11-40.) Rods shall be cut so that they extend 1/8 to 1/4 inch beyond the surface of the grommet when bottomed against the end of the spare contact. (See table 11-26 for dimensions.)
PRESSURIZED AREAS. Connectors installed in pressurized areas of the aircraft may be divided into two main installation categories, sealed and unsealed.
Sealed connector installations. Sealed connectors installed in pressurized areas must have their unused contact cavities filled with Teflon sealing plugs or rods.
(See figure 11-40.) Installation of spare contacts is optional, except for future wiring addition requirements.
(See paragraph 11-234). No stub wires are required.
Unsealed Connector Installations. It is not required to fill unused contact cavities of unsealed connectors installed in pressurized areas with Teflon sealing plugs or rods. Installation of spare contacts is optional, except for future wiring additi on requirements. (See paragraph 11-234.)
Par 11-271 Page 11-585 TABLE 11-25. Contact cavity sealing-quick reference.
Connector Installation Types Unpressurized Area Sealing Means Firewall
Non-Firewall Sealing Plugs or Teflon Sealing Rods
No
Yes Stub Wires (Note 2) Yes No Spare Contacts Yes Yes NOTE 1: Sealing plugs may be included with the spare connector and may be used for sealing unused contacts. Sealing rods are procured from stock by the foot. (See table 11-26 for sealing rod dimensions.)
NOTE 2: Stub wires must be of the same type as the other wires of the bundle.
F IGURE 11-39. Stub wire installation.
TABLE 11-26. Sealing rod dimensions.
CONTACT SIZE DIAMETER ROD LENGTH (INCHES) (AWG) (INCHES) MIN MAX 20 1/16 5/8” 3/4” 16 3/32 7/8” 1” 12 1/8 7/8” 1”
FIGURE 11-40. Sealing unused contact cavities-unpressurized areas-(cut-away view).
11-264.11-270. [RESERVED.]
Par 11-271 Page 11-586 SECTION 20. ELECTRICAL AND ELECTRONIC SYMBOLS
GENERAL. The electrical and electronic symbols shown here are those that are likely to be encountered by the aviation maintenance technician. They are in accordance with ANSI-Y32.2-1975.
SYMBOLS. Only those symbols associated with aircraft electrical and electronic wiring have been listed in general. Refer to ANSI- Y32.2-1975 for more specific detail on each symbol.
TABLE 11-27. Electronic/Electrical Symbols.
Symbol Meaning
Adjustability Variability
Radiation Indicators
Physical State Recognition
Test-Point Recognition
Polarity Markings
Direction of Flow of Power, Signal, or Information
Kind of Current
Envelope Enclosure
Shield Shielding
Special Connector or Cable Indicator
Par 11-271 Page 11-587 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Resistor
Capacitor
Antenna
Battery
Thermal Element Thermomechanical Transducer
Thermocouple
Spark Gap Ignitor Gap
Continuous Loop Fire Detector (Temperature Sensor)
Ignitor Plug
Par 11-272 Page 11-588 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Transmission Patch Conductor Cable Wiring
Distribution Lines Transmission Lines
Alternative or Conditioned Wiring
Associated or Future
Par 11-272 Page 11-589 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Intentional Isolation of Direct-Current Path in Coaxial or Waveguide Applications
Waveguide
Strip-Type Transmission Line
Termination
Circuit Return
Pressure-Tight Bulkhead Cable Gland Cable Sealing End
Switching Function
Electrical Contact
Par 11-272 Page 11-590 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Basic Contact Assemblies
Magnetic Blowout Coil
Operating Coil Relay Coil
Switch
Pushbutton, Momentary, or Spring-Return
Par 11-272 Page 11-591 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Two-Circuit, Maintained, or Not Spring-Return
Nonlocking Switching, Momentary, or Spring- Return
Locking Switch
Combination Locking and Nonlocking Switch
Key-Type Switch Lever Switch
Par 11-272 Page 11-592 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Selector or Multiposition Switch
Safety Interlock
Limit Switch Sensitive Switch
Switches with Time-Delay Feature
Flow-Actuated Switch
Par 11-272 Page 11-593 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Liquid-Level Actuated Switch
Pressure- or Vacuum-Actuated Switch
Temperature-Actuated Switch
Thermostat
Flasher Self-Interrupting Switch
Foot-Operated Switch Foot Switch
Switch Operated by Shaft Rotation and Responsive to Speed or Direction
Switches with Specific Features
Par 11-272 Page 11-594 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Governor Speed Regulator
Relay
Inertia Switch
Mercur Switch
Terminals
Par 11-272 Page 11-595 TABLE 11-27. Electronic/Electrical Symbols (continued).
Symbol Meaning
Cable Termination
Connector Disconnecting Device
Connectors of the Type Commonly Used for Power-Supply Purposes
Test Blocks
Coaxial Connector
Waveguide Flanges Waveguide Junction