Chapter 5 - Section 1: Basic principles and block installation diagrams

Question 1

What are the internationally agreed requirements of a CVR installation?

Answer 1

• Last 30 minutes of flight deck communications (internal and external) and ambient noises will be retained on an endless magnetic tape
• The recording will survive the physical extremities of high impact, extremely high temperatures and long immersions in water (usually sea water)

Question 2

What are the four channels of a CVR?

Answer 2

1. Flight engineer (or other parameters in helicopters) - track 4
2. First officer - track 1
3. Captain - track 2
4. Area microphone - track 3

Question 3

Why are the most critical tracks, captain and area microphone, made to be track 2 and 3?

Answer 3

These would be the inside tracks of a four-track tape, therefore if some damage were to occur to the outside tracks, these would have maximum integrity

Question 4

Given that channels 1, 2 and 3 are crew audio, what is peculiar about the selected microphone at each position?

Answer 4

It is live or ‘hot’, even without transmitting

Question 5

Why is the 115V supply to the CVR off the essential bus and not the emergency bus?

Answer 5

So that in an electrical emergency, the supply for emergency circuits is not jeopardised by keeping CVR and DFDR circuits running

Question 6

What are the interlocks required to allow the Bulk Erase facility?

Answer 6

• Weight-on-wheels
• Parking brake applied
• Or, any passenger door open

Question 7

What indications will a self test facility give?

Answer 7

• Green pass indication on the meter when the test switch is pushed
• 600 Hz tones heard in the headphone jack

Question 8

Describe the operation of the Underwater Locating Beacon (ULB)?

Answer 8

• Battery operated
• Water-sensitive switch
• Ultrasonic frequency of 37.5 kHz
• Should last 90 days