Electronic Data Management Systems: How It Works
The basics of electronic data management systems (EDMS) in aircraft are pretty simple. The EDMS essentially consists of two parts – probes & sensors and the display unit(s). The probes and sensors are located at various critical parts of the aircraft and convert heat, pressure or whatever it is supposed to sense, into electrical signals usually in the form of volts. These signals are interpreted by the display unit and displayed in a manner that makes sense to the pilot(s).
There are two types of probes and sensors used in modern aircraft; internal and external. For obvious reasons, most of the probes and sensors are located in and around the aircraft engine. The internal probes include the CDT Probe, CHT Bayonet Probe, EGT Probes, CHT multiple Probes, IAT Probe, TIT probe, CHT Gasket Probe, CRB Probe,Fuel Flow Transducers,Manifold Pressure Sensor, OAT Probe, Oil Temp Probe, RPM Sensor for Bendix Mag, RPM Sensor for Slick Mag and so forth.
The external probes or sensors include Ice detectors, Multi-function probes, Static port, TAT probe, Side-slip vane, Pitot probe (or tube), Angle-of-attack vane and so forth. Now, not all aircraft have all of these probes and sensors but most will have a combination of some of these.
In days gone by, each probe or probe set would be connected to a analog gauge located in the cockpit. With the new electronic data management systems (EDMS) however, each set of probes covering a specific area or function is connected to one display unit. So, most probes that measure engine function will be connected to a single EDMS unit in the cockpit. The external probes would be connected to another similar unit. So instead of having a couple of dozen different dials and Slimline Pressure Gauge in the cockpit, the modern aircraft has just a few interconnected electronic data management systems (EDMS) that monitor everything inside and outside the aircraft.
The EDM (check out the J.P. Instruments website https://www.jpinstruments.com/ for different types of single and twin engine EDM's) can either work as a stand-alone display unit or in some cases, be interconnected with other EDM's to provide a more wider picture of the aircraft status.
Each EDM is a mini computer on its own fully capable of accepting pilot inputs before each flight and providing downloadable data after each flight. Each electronic data management system is capable of independently monitoring its allotted function and display an alarm if something suspicious happens. Examples would be build up of excessive temperature or pressure or low Fuel Gauges levels and so forth.
With integration of EDM's, they were able to accept data from each other and use that data to produce a different set of information. For example, current fuel level, current rate of fuel consumption, current position (as indicated by GPS), target destination (as entered by pilot before or during flight) is used to compute flight viability i.e. whether the aircraft can safely reach target destination with fuel to spare. You wouldn't be wrong in thinking all this should be pretty simple. But the fact is, until recently the pilots had to do all the calculations himself and larger aircraft even had a flight engineer onboard.
