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Boeing 777 FDRs/CVRS Informational

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Boeing 777 FDRs/CVRS Informational

Old 1st Jul 2014, 20:28
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Boeing 777 FDRs/CVRS Informational

Since there is great interest in another thread as to the workings of the
T7's FDR/CVR and powering...this is from my old training manual...had to blow the dust off and copy...so forgive any errors.



Voice Recorder System - Interface

Power

The cockpit voice recorder (CVR) gets 115v ac from the
VOX RCDR circuit breaker. The CVR supplies 18v dc to
the audio amplifier in the cockpit voice recorder
panel.

Relays

The K32001 parking brake relay gets 30v dc from the
CVR. When the parking brake is on, the relay closes.
The relay sends 30v dc to the K32216 ground mode relay.
The K32216 ground mode relay gets 30v dc from the
closed K32001 parking brake relay. When the airplane is
on the ground, K32216 closes. The relay sends 30v dc to
the cockpit voice recorder panel. This 30v dc goes to
the erase switch.

Cockpit Voice Recorder Microphone

The cockpit voice recorder microphone sends area audio
to the cockpit voice recorder panel.

Cockpit Voice Recorder Panel

The cockpit voice recorder panel sends these signals:
- Area audio to the channel 4 input of the CVR
- Test discrete to the CVR
- Erase discrete to the CVR

Audio Management Unit

The audio management unit (AMU) sends these signals:
- First observer (F/OBS) audio to the channel 1
input of CVR
- First officer (F/O) audio to the channel 2 input
of the CVR
- Captain (CAPT) audio to the channel 3 input of CVR.

Cockpit Voice Recorder

The CVR sends these signals:
- 30v dc to the parking brake relay
- Test results to the cockpit voice recorder panel
- Audio to the cockpit voice jack on the P40 service
and APU shutdown panel
- Audio to the cockpit voice recorder panel.

The CVR gets these signals universal coordinated time
(UTC) from the left AIMs cabinet



VOICE RECORDER SYSTEM - FUNCTIONAL DESCRIPTION

General

The voice recorder system receives flight deck sounds
and flight crew communications. It keeps this audio in
a solid state memory. The voice recorder system has
these modes of operation:
- Normal operation
- Erase
- Test.

Normal Operation

With power on the airplane and the cockpit voice
recorder (CVR) circuit breaker closed, the CVR operates
continuously.
Four audio channels go to the CVR. Channel 1, 2, and 3
audio is from the audio management unit (AMU). Each
channel carries audio from one crew member's flight
interphone audio. The audio on each channel is the sum
of these signals:
- Hot mic audio (microphone audio when there is no
PTT)
- Received audio as selected on the crew member's
audio control panel (ACP)
- Sidetone audio to the crew member.
Channel 4 audio is from the cockpit voice recorder
microphone. The cockpit voice recorder microphone sends
flight deck area audio to the CVR. The CVR panel gets
18v dc for the preamplifier from the CVR. Thepreamplifier
in the panel increases the strength of the
channel 4 audio and sends it to the CVR.
30v dc bias signal is a record enable signal from the
airplane interface through an external jumper back to
the airplane interface.
All audio goes to the CVR airplane interface. The
airplane interface has these functions:
- Monitors power in the CVR
- Changes the format of input and output signals
- Controls the audio record process.
When CVR power is not in tolerance, the airplane
interface sends a low power discrete to turn off other
CVR circuits.
The airplane interface changes the input audio signals
in the A/D-D/A circuits for use by the audio processor.
The airplane interface sends a record discrete to the
audio processor and store processor to start the record
process.
The audio processor samples the flight deck audio
signals 8,000 times per second and the cockpit voice
recorder microphone audio signals 12,000 times per
second. It changes the analog signals to digital
signals. These signals go to the store processor on the
digital audio bus.
The audio processor also mixes the four digital signals
and sends them to the airplane interface. The airplane
interface sends these signals to headphone jacks in
these locations:
- Cockpit voice recorder panel
- P40 service and APU shutdown panel.
The store processor uses signals on the control bus to
control the functions of the flash memory. The store
processor sends address signals to the flash store on
the address bus. The addresses tell the flash memory
where to keep the digital data. The data goes to the
flash memory on the data bus.
The flash memory keeps the digital data in a first-in,
first-out solid state memory.
The CVR gets universal coordinated time (UTC) data from
the left AIMs cabinet. UTC data is sent to both the CVR
and the flight data recorder (FDR). CVR and FDR events
are synchronized using UTC data

Test
Push and hold the TEST switch on the cockpit voice
recorder panel to start a CVR self test. Hold the
switch for a minimum of five seconds. The cockpit voice
recorder panel sends a ground discrete to the airplane
interface circuits in the CVR. The airplane interface
sends this test discrete to the audio processor and to
the store processor.

In the audio processor, the test discrete enables a
tone generator. The tone generator sends a 620 Hz. tone
to A/D-D/A circuits. They change the tone to a digital
signal. The audio processor connects the digital tone
in sequence to each of the four audio inputs of the
store processor.
In the store processor, the test discrete enables the
flash memory to store the digital test tones for each
channel. It also enables the store processor to
playback the test tones from the flash memory. The
store processor sends the digital playback signals back
to the audio processor.
The audio processor changes the digital signals to
analog signals. It mixes the four signals into one
audio signal and sends it to these locations:
- Test meter
- Cockpit voice recorder panel headset jack
- P40 service and APU shutdown panel.
The test meter reads the strength of the audio signal
and shows it on the meter dial on the cockpit voice
recorder panel. The meter needle moves to the green
area of the meter dial for a normal test. The needle
stays in the green area while you hold the TEST switch.
The store processor monitors for faults. When it finds
one, it sends a fault signal to the airplane interface.
When it detects the fault signal, the airplane
interface keeps the audio signal from the meter.
You monitor the 620 Hz test tone at any of the headset
jacks.

Erase

When the airplane is on the ground with the parking
brake on, you push and hold the ERASE switch on the
cockpit voice recorder panel to erase the CVR.
The airplane interface in the CVR sends 30v dc to
K32001 parking brake relay. When the parking brake is
on, the relay closes.
The 30v dc goes through the K32001 relay to K32216
ground mode relay. When the airplane is on the ground,
the relay closes. The 30v dc goes through the K32216
relay to the ERASE switch in the cockpit voice recorder
panel.
When you push the ERASE switch, the 30v dc goes to the
airplane interface in the CVR. The airplane interface
sends this erase discrete to the audio processor and
the store processor.
In the audio processor, the erase discrete disables the
A/D-D/A circuits. The store processor sends the erase
discrete to the flash memory. The flash memory erases
all data in the memory.



FDRS - System Interface

General

The flight data recorder system (FDRS) gets digital
data and digital discrete data on ARINC 629 and ARINC
429 data buses. The FDRS also receives analog inputs
from some of the airplane systems and sensors. The FDR
receives power from the power management panel. The FDR
sends analog data to the digital flight data
acquisition functions (DFDAF) of AIMS.
The left AIMS cabinet sends DFDAF data on an ARINC 717
data bus to the FDR. If the left AIMS cabinet DFDAF
fails, the right AIMS cabinet sends DFDAF data to the
FDR. The DFDAF sends fault data, status and test result
data to the CMCF and the display system functions
within the AIMS cabinets.

Power

The FDR receives power from the P210 right power
management panel. DFDAF uses engine, air/ground, and
ground test logic to determine when to turn on the FDR.

Analog Data

The DFDAFs receive status and maintenance flag data
from the FDR. The DFDAFs receive key events from the
VHF and HF LRUs and variable analog data from TAT, AOA
and engine RPM sensors.

Digital Data

The systems ARINC 629 buses provides engine, airframe
data, and air/ground logic. This is the engine data:
- Engine parameters, normal and exceedances
- Commands
- Actual thrust.
This is the airframe data:
- Flight deck switch position
- Flight controls positions
- Mode selections on control panels in the flight deck.
The DFDRS receives status from the engine and airframe
sensors. The DFDRS also receives data and status from
the electrical power system.
The flight controls ARINC 629 buses provide flight data
and navigation data. This is the flight data:
- Flight control position
- Commands
- Status.
This is the navigation data from the ADIRU and SAARU:
- Pitch, roll and yaw attitude
- Acceleration data
- Status.



FDRS - Functional Description

General

The flight data recorder (FDR) receives and records the
last 25 hours of data. The FDR receives the data from
the DFDAF. The FDR records the data in a solid-state
memory. The memory is in a crash-proof, fire-resistant
container. The FDR also monitors and sends fault data
to the DFDAF.

Recording Data

The AIMS digital flight data acquisition function
(DFDAF) sends data on a high speed data bus (ARINC 717)
to the FDR. In the FDR, the receiver processes and
sends the data to the microprocessor. The
microprocessor receives, processes and stores the data
in a crash survival solid-state memory. Data is
recorded at 128 words/second.

Data Downloading

The front mounted automatic test equipment (ATE)
connector on the FDR provides a connection for:
- ATE or ramp test equipment for recorder checkouts
on or off the aircraft
- Data download to a portable data unit while on or
off the airplane.

Non-normal Conditions

The FDR microprocessor sends these two discretes to the
AIMS DFDAF:
- System status flag
- Maintenance flag.
The system status flag discrete causes a system level
alert. A maintenance flag discrete causes a FDR
internal failure. When a FDR fails, the FDR sends both
discretes. When the AIMS DFDAF receives either
discrete, EICAS (PDF) shows a FLT RCDR SYS status
message. The AIMS DFDAF also sends the fault data to
the AIMS CMCF.
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