777 AIRCRAFT MAINTENANCE MANUAL
FDRS -FLIGHT DATA RECORDER
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FDRS -UNDERWATER LOCATING DEVICE
Purpose
The underwater locating device (ULD) is an ultrasonic beacon. It makes the flight data recorder (FDR) easier to find if it is underwater.
Physical Description
The ULD is a line replaceable unit that is 1.3 inches in diameter and 4 inches long. It weighs less than 12 ounces.
Power
The ULD receives power from a 9.6 volt DUKANE model DK100 battery.
Functional Description
The ULD has these operational characteristics:
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Operates when it is put into water
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Operates to a maximum depth of 20,000 feet
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Has a detection range of 7,000 to 12,000 feet
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Has an operational life of 30 days underwater
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Sends out an acoustic pulse tone of 37.5 kHz at a rate of one pulse-per-second.
Training Information Point
The DK100 ULD uses a lithium battery. If not activated, it has a life of six years. It is important to keep the water switch contacts clean. The battery is not a line replaceable unit.
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777 AIRCRAFT MAINTENANCE MANUAL
FDRS -UNDERWATER LOCATING DEVICE
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777 AIRCRAFT MAINTENANCE MANUAL
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FDRS -DFDAF FUNCTIONAL DESCRIPTION
General
The digital flight data acquisition function (DFDAF) is software in each AIMS cabinet. The DFDAF collects data from:
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ARINC 629 buses
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ARINC 429 buses
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Analog discrete inputs
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Analog inputs.
The DFDAF reformats, organizes, and transmits this data to the FDR.
The DFDAF controls power to the FDR. The FDR records and monitors the fault status of the FDR system when it receives power. The FDR sends fault information to the central maintenance computing function (CMCF) and the primary display function (PDF) in AIMS.
ARINC 717 Interfaces
The AIMS core processor module/communication module (CPM/Comm) supplies ARINC 717 interfaces to the DFDAF. The AIMS DFDAF interfaces with the FDR via ARINC 717. Each of the AIMS cabinets has an ARINC 717 transmitter and a ARINC 717 bus for the FDR.
The output from the right AIMS cabinet goes to a source select relay in the left AIMS cabinet. The source select relay uses the output from the left or right DFDAF for the FDR. Software in the left AIMS cabinet controls the position of the source select relay. When the source select relay energizes, the left AIMS cabinet ARINC 717 output goes to the FDR.
DFDAF
Normal operation of the FDRS is automatic. The DFDAF is in both the left and right AIMS cabinets. The normal source of the data sent to the FDR is from the DFDAF in the left AIMS cabinet. If the left DFDAF fails, the DFDAF in the right AIMS cabinet automatically sends data to the FDR. In this case, the source select relay de-energizes. The DFDAF automatically collects, reformats and transmits data to the FDR shortly after the AIMS cabinets receive power.
The DFDAF continuously monitors airplane status to determine when to turn on the FDR and when to transmit data to the FDR. The DFDAF turns on the FDR when any one of these occur:
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Any engine is in start mode (starter air valve switch in START position or fuel cutoff lever not in CUTOFF position)
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Any engine is in the RUN mode (N1 RPM>20% or N2 RPM>20%)
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The airplane is airborne (from weight on wheels card in systems cardfile).
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FDRS -DFDAF FUNCTIONAL DESCRIPTION
To supply power to the FDR, the DFDAF sends a digital discrete to the electrical load management system (ELMS) power management panel. The power management panel sends a ground to energize a relay in the panel and pass power to the FDR.
The DFDAF receives these two discrete inputs from the FDR:
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Maintenance flag
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System status flag.
The maintenance flag discrete shows a FDR internal failure. A system status flag shows a system level failure such as:
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