Flight Data Recorder (FDR) is designed to fix the basic parameters o flight of aircraft and functional parameters of different systems in case of undesirable situations for further their reproduction during the investigation of aviation accidents.
Regulatory documents require the presence of FDR of certain class on each aircraft. Requirements for the construction and fixed parameters are changing and becoming more stringent.
On older FDR systems parameter values were recorded in analog form using a needle and a metal foil. Later the tape was used as data carrier. However, at present in most of countries digital media drives in the FDR construction are regulated. Modules of the solid-state electronic memory effectively protect the recorded data from elastic shock, fire, high temperatures and long stay under seawater. Moreover, Digital Flight Data Recorders (DFDR) provide more recording channels which provide a record of all flight parameters and allow to store more recorded flight hours than their predecessors. It is important to record not only the parameters of the flight, but the conversation in the cockpit of aircraft too. For this purpose special Cockpit Voice Recorder (CVR) is applied. Modern CVRs also use solid-state electronic memory which provides a record of flight crew and ACTO conversations and conversations in the cockpit by means of special microphones. Application of DFDR for the fixing of flight information requires appropriate equipment which provides its functioning. The Digital Flight Data Recorder System (DFDRS) includes recording devices, sensors, connection cables and other elements necessary to carry out its functions.
The main constituent elements of DFDRS are:
- Flight Data Acquisition Unit (FDAU) which provides the collection of data from different aircraft systems and conversion of collected data into digital ones. Data in digital form from FDAU transmit to DFDR with the help of one of the DDB (ARINC 473, ARINC 717);
- Back-up power sources;
- Underwater Locating Device (ULD) which emits search signals for signalization of aircraft location in case if DFDRS turned in the water environment.
Important for the development and construction of DFDRS is the providing of individual power supply channel as the possibility of fixing of flight parameters clearly depends on the power supply.
There are flight data registration systems which perform the functions of CVR and DFDRS. The example of such a typical system is shown in Fig. 199.
Fig. 199. Digital Flight Data Recorder
The information stored in DFDRS, is used only in cases of investigation of aviation accidents. To analyze the flight parameters and faults detection of different aircraft systems functioning Quick Access Recorders (QARs) are used. QAR device is similar to DFDRS and provides registration of all flight parameters and parameters that characterize the work of different aircraft systems (Fig. 200).
Fig. 200. Equipment for recording information onboard of aircraft
Data with the help of QAR are recorded in the internal memory or on the removable digital storage media, which is replaced by the pilot before each flight.
Analysis of the recorded information using special software allows technical personnel to detect certain shortcomings in the functioning of the systems and locate their causes.