venerdì 23 settembre 2016

Avionics bending: CVR

1. General

A. The voice recorder system preserves a continuing record of the latest 30 or 120 minutes of flight crew communications and conversations. The four channel voice recorder receives inputs from the audio selector panels for the captain, the first officer, and the first observer, and from an area microphone in the flight compartment.

B. The voice recorder system consists of a recorder located in the aft passenger cabin ceiling and a control panel with an area microphone located on overhead panel P5.

C. 115 VAC power is supplied to the system from the right AC bus. The VOICE RECORDER circuit breaker, located on overhead panel P11, controls power to the system.

2. Component Details

A. Voice Recorder


The voice recorder is installed in the E7 equipment rack in the aft passenger cabin ceiling. The recorder is a thermally insulated, impact resistant, 4 MCU unit, and international orangein color.

The voice recorder contains a tape transport which includes the tape, tape drive, two four-track recording heads, two erase heads, two monitor heads, and a bulk erase coil. The unit also contains four recording amplifiers, a monitor amplifier, 65 kHz bias generator,
600 Hz test circuits and power supply.
(a) The recording tape is 308 feet long, 1/4 inch wide in a continuous endless loop. The four track tape runs at 1 7/8 IPS providing 30 minutes of recording time.
(b) The front panel contains a headphone jack and a underwater locator beacon (ULB). A headset inserted into the headphone jack will monitor all channels slightly delayed after they are recorded.
(3) An ULB is attached to the voice recorder front panel and is a self-contained device. The ULB will emit a 37.5-KHz signal when the water activated switch is closed. The ULB contains a dated label to indicate when the battery requires periodic replacement.

B. Voice Recorder Control Panel

The voice recorder control panel is located on overhead panel P5.
It contains an area microphone with preamplifier and filter circuits, a HEADPHONE jack to monitor system recording, a TEST switch to initiate the functional self test, a light or meter to
provide an indication of self test success or failure, and an
ERASE switch for data erasure.

Push the TEST switch will activate test circuits within the voice recorder. A tone is applied to all four channels. If the test is successful, the needle on the monitor meter moves and stays in the green area and you hear a tone in the headse

Push the ERASE switch will cause the voice recorder data to be completely erased. Bulk erasure is possible only when the airplane is on the ground with the parking brake set.