6.11- Electrical Cables and Connectors

Question 1

What is a wire?

Answer 1

An isolated single copper conductor surrounded by insulation.

Question 2

What is a cable? (Electrical)

Answer 2

Group of two or more conductors separately insulated and grouped together by an outer sleeve.

Question 3

What is a stranded copper conductor normally used for and what are the strands often coated in?

Answer 3

Maximum wire flexibility

Tin, nickel or silver.

Question 4

What are wires with aluminium conductors used for?

Answer 4

Large loads like galleys to save weight.

Question 5

What are the requirements for materials used as insulation?

Answer 5

Voltage resistant up to 600V
Resistant to aircraft fluids
Flexible
Strong
Lightweight

Question 6

What are the bands of temperature that wire types are categorised into (Normal, high and very high)?

Answer 6

100/150°c
250°c
400°c

Question 7

What are shielded wire types used for?

Answer 7

To protect against erratic signals or magnetic interference.

Question 8

In signal circuits operating below 50KHz how is maximum shielding protection provided?

Answer 8

By grounding the shield on one side only, this prevents back-flow of current.

Question 9

What is different about the grounding of the shield on ARINC 429 data bus?

Answer 9

Its grounded at both ends instead of just one.

Question 10

What is coaxial cable used for?

Answer 10

To transport high frequency signals.

Question 11

Which sides of coaxial cable are grounded for best transmission?

Answer 11

Both sides.

Question 12

For Boeing wire type codes what should you refer to?

Answer 12

SWPM 20.

Question 13

For Airbus wire type codes what should you refer to?

Answer 13

ESPM 20.

Question 14

What does BMS stand for?

Answer 14

Boeing Material Specification.

Question 15

What is BMS 13-28 equal to in MIL spec?

Answer 15

MIL-W 7139

Question 16

What is Boeing Type 1 Wire?

Answer 16

Insulated wire with one conductor

Question 17

What is Boeing Type 2 Wire?

Answer 17

Type 1 with shield.

Question 18

What is Boeing Type 3 Wire?

Answer 18

Type 2 with yet another shield.

Question 19

What is Boeing Class 1 wire?

Answer 19

Single insulated wire.

Question 20

What is Boeing Class 2 wire?

Answer 20

Two insulated wires.

Question 21

How does the Boeing wire size numbering system work?

Answer 21

Its a reverse numbering system to represent the current carrying capacity.

Question 22

All single wires and multi conductors (red wire only) should have what?

Answer 22

A manufacturers legend in a contrasting colour at intervals of 100-150mm.

Question 23

What should the manufacturers legend on a wire include?

Answer 23

Spec
Manufacturer
Country of origin
Year of manufacture
Wire size (AWG)

Question 24

How can wires be marked?

Answer 24

Mechanical printing
Ink-jet
Co2 laser
UV laser.

Question 25

What are the boeing rules for wire marking?

Answer 25

``` Must be marked at each end within 10cm. Biggest marking interval is 72in Upper case easily read at 15in Minimum contrast of 55% ```

Question 26

In system wire coding what does the second letter provide?

Answer 26

A more detailed description of the system.

Question 27

What system does the letter coding SA represent?

Answer 27

Radio Altimeter.

Question 28

If there is more than one system then how are numbers used before the system code?

Answer 28

A number is placed before the letters e.g. 1 SA or 2 SA | Radio altimeter system #1

Question 29

Common use for system wiring is identified using what system?

Answer 29

ATA 100.

Question 30

What is a WDM?

Answer 30

Wiring diagram manual.

Question 31

How is wire size denoted?

Answer 31

Through the use of the American wire gauge (AWG), it is reverse numbered.

Question 32

In the Wire code W104-G-299-22R what do the separate parts represent?

Answer 32

``` W104- Wire bundle G- System code 299- Wire no. 22- Wire size R- Colour code. ```

Question 33

What is the difference between an even bundle no. and an odd bundle no.?

Answer 33

An even no. is electrical system and an odd is an electronic system.

Question 34

In airbus system coding what do the first two and third/fourth digits refer too?

Answer 34

First two= ATA Chapter | Third/fourth= ATA sub chapter

Question 35

If the number of wires in which 100% current is flowing is lower, then what will happen to the maximum current flow?

Answer 35

It will increase.

Question 36

What is one of the main advantages of aromatic polymide?

Answer 36

Saves 50% weight and 30% space.

Question 37

At what temperature does Aromatic polymide smoulder at?

Answer 37

815°C

Question 38

What phenomena is known to destroy Aromatic Polymide?

Answer 38

Carbon arc tracking.

Question 39

What two categories are there of carbon arc tracking?

Answer 39

Dry and wet.

Question 40

What is dry carbon arc tracking?

Answer 40

Wire to wire or wire to ground, carbon build up.

Question 41

What is wet carbon arc tracking?

Answer 41

Fluid build up instead of carbon in dry arc.

Question 42

What are Exhaust gas temperature cable conductors made from?

Answer 42

Chromel and Alumel.

Question 43

What makes the identification of a thermocouple wire different to a standard wire?

Answer 43

The colours are different, often white/green.

Question 44

For fire warning wires what is the maximum fire resistance?

Answer 44

1093°C for 5 minutes.

Question 45

What must fire warning wire conform too?

Answer 45

MIL-W-25038

Question 46

What are electrical connectors used for?

Answer 46

To allow maintenance where frequent disconnection is required.

Question 47

What is a more modern and common way of connecting a contact to a connector? Solder or crimping?

Answer 47

Crimping.

Question 48

What must be used to terminate aluminium cables?

Answer 48

Aluminium or bimetal (AlCu) terminations.

Question 49

Which side of the connector will have a socket instead of the pins?

Answer 49

The 'hot' side as it avoids the risk of electric shock.

Question 50

What two basic groups of connector are there?

Answer 50

``` Split shell (disassembled) Assembled construction. ```

Question 51

How are split shell connectors identified?

Answer 51

By AN numbers.

Question 52

How many types of AN connector are there in how many classes?

Answer 52

Six types in 5 classes.

Question 53

What is a Class A AN connector?

Answer 53

General purpose, one piece back shell.

Question 54

What is a Class B AN connector?

Answer 54

Back shell is two parts.

Question 55

What is a Class C AN connector?

Answer 55

Pressurised connector.

Question 56

What is a Class D AN connector?

Answer 56

Moisture and vibration resistant.

Question 57

What is a Class K AN connector?

Answer 57

Fireproof connector. Made of steel.

Question 58

What are the most common connector type?

Answer 58

Assembled connector.

Question 59

What does an assembled connector consist of?

Answer 59

Insert locking mechanism and insulator. The backing clamp is a separate part and has a different part number.

Question 60

For circular connectors, the master keyway is always positioned in which direction?

Answer 60

Either top dead or facing forward to the aircraft.

Question 61

How is shell size denoted?

Answer 61

1/16 inch, and the letter S is used to denote a short housing.

Question 62

For a plug to be environmentally sealed what must be done with any unused contact holes?

Answer 62

Fitted with nylon or tTeflon seal plugs.

Question 63

For crimped contact connectors outside the pressurised area what must be fitted?

Answer 63

Unwired contacts in conjunction with seal plugs.

Question 64

Where can you find alternative part numbers and manufacturers?

Answer 64

In the standard practices manual.

Question 65

What is a polarisation key?

Answer 65

Prevents the wrong computer being inserted into a shelf.

Question 66

What must be done to to non-self locking threaded coupling connectors located in high vibration areas?

Answer 66

They must be lockwired.