Chapter 3 - Section 1: Basic principles

Question 1

How might crosstalk be defined?

Answer 1

The reception in the phones (or speaker) of an unselected receiver at any crew member’s position

Question 2

What is the condition for crosstalk to occur?

Answer 2

Two ASPs must have a common selection

Question 3

What is the most common method of minimising crosstalk interference?

Answer 3

Attenuate the unselected path by use of resistive potential dividers

Question 4

Why might crosstalk occur in cases of emergency?

Answer 4

If power supply to the ASP is lost, the amplifier will not work

Amplifier bypass will still result in 32 dB attenuation, thus any emergency provision must bypass the crosstalk network as well as the amplifier

Question 5

What is the only intercom INT system?

Answer 5

Flt Int

All other systems are R/T systems and require the I/C-R/T switch to be operated to R/T except for Flt Int

Question 6

Why will one or more microswitches isolate all the interphone sockets when the aircraft becomes airborne?

Answer 6

So that any moisture that might get into an external socket will not short out a live circuit