The Aircraft Condition Monitoring System (ACMS) provides a record of selected airplane systems performance and flight conditions for maintenance and Flight Data Monitoring purposes. The system consists of a Digital Flight Data Acquisition Unit, a Digital Flight Data Recorder (DFDR), a Quick Access Recorder, an accelerometer and a Data Management and Entry Panel.
With airplane busses powered, the ACMS will begin operating as either engine starts (on the ground). In the air the ACMS will be powered (even with both engines shut down) as long as the APU is powering the busses.
The Digital Flight Data Acquisition Unit (DFDAU) receives signals representing certain flight conditions and airplane systems' operating performance and converts them to a digital form for recording on the DFDR and QAR.
The Quick Access Recorder (QAR) provides approximately 14 hours of recorded airplane systems and flight information on a tape cassette. The DFDR and QAR record the same information. After a cassette has been locked in the QAR it will operate simultaneously with the DFDR. An indicator light on the QAR will illuminate when the tape cassette requires replacement. The QAR is located in the Forward E/E compartment.
The Data Management and Entry Panel (DMEP) contains the controls and indicators for operation of the ACMS.
The Digital Flight Data Recorder (DFDR) provides a permanent record of selected operational systems in a sealed, fire-resistant container located in the aft fuselage area. The recorder automatically turns on when either engine is operating or the airplane is in flight. The flight data recorder writes the data for the last 25 hours of airplane operation on to a continuous loop of magnetic tape.
As installed
The recorder can be manually turned on by selecting TEST or ON with the Flight Recorder Switch.