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. http://img11.hostingpics.net/pics/240678cvri.png 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 http://img11.hostingpics.net/pics/331707cvrf.png 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. http://img11.hostingpics.net/pics/598893fdrsi.png 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. http://img11.hostingpics.net/pics/625318fdrsf.png 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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