Updated: Sep 18, 2020
The Engine Indication and Crew Alerting System (EICAS) is designed to provide all engine instrumentation and crew annunciations in an integrated format. The equivalent system on Airbus aircraft is the Electronic Centralized Aircraft Monitoring (ECAM) system.
The information supplied by EICAS/ECAM includes display of engine torque, inter-stage turbine temperature, high and low pressure gas generator RPM, fuel flow, oil temperature and pressure. As part of the EICAS, graphical depiction of aircraft systems can be displayed. Such systems as electrical, hydraulic, de-icing,
environmental and control surface position can be represented. All aircraft messages relating to these systems are also displayed on the EICAS.
EICAS improves reliability through elimination of traditional engine gauges and
simplifies the flight deck through fewer standalone indicators. EICAS also reduces crew workload by employing a graphical presentation that can be rapidly assimilated. EICAS can also help to reduce operating costs by providing maintenance data.
A typical EICAS comprises two large high resolution, colour displays together with associated control panels, two or three EICAS data concentrator units and a lamp driver unit.
The primary EICAS display presents primary engine indication instruments and relevant crew alerts. It has a fixed format providing engine data including:
• RPM and temperature
• fuel flow and quantity
• engine vibration
• gear and flap details (where appropriate)
• Caution Alerting System (CAS) messages (colour coded to indicate importance).
The secondary EICAS display indicates a wide variety of options to the crew and serves as a backup to the primary display. They are selectable in pages using the EICAS control panel and include the display of information relating to:
• landing gear position
• auxiliary power unit
• cabin pressurisation/anti-ice
• flight control positions
• AC and DC electrical data.
The EICAS displays receive data bus inputs from the EICAS Data Conversion Unit (DCU). The EICAS displays provide data bus outputs to the Integrated Avionics Processing System (IAPS) Data Concentrator Units (DCU). Note that the pilot or co-pilot can select either display. Selecting one display blanks the second display and allows data pages to be selected. The EICAS control (ECU) panel is used to select pages. The information on the data buses is routed to both EICAS displays and both multifunction displays.
The DCU receives data in various formats from a variety of sensors, including the high and lowspeed ARINC 429 bus, from analogue and discrete inputs from the engines and other aircraft systems. These are concentrated and processed for transmission on system buses (ARINC or otherwise).
Outputs include crew alerting logic, engine data to the displays, maintenance, diagnostic and aircraft data to the IAPS DCU, indicator lamp data to the LDU, aircraft system data to the Flight Data Recorder (FDR) and data link management unit. The Lamp Driver Unit (LDU) is a dual channel unit capable of driving up to 120 indicator lamps. Channels 1 and 2 receive digital buses from all the DCU. The buses convey lamp activation words from the DCU. Channels 1 and 2 are identical and the outputs from each side are tied together (wired-OR logic). If one channel lamp sink fails, the other channel lamp sink will provide the function. The LDU monitors the lamp sinks to verify correct function and outputs the lamp sink states on a digital bus to the DCU.
The Electronic Routing Units (ERU) are junction boxes for the data concentrator units. The ERU splits each input signal to three output pins. The pilot ERU routes left-side airplane data and the co-pilot ERU routes right-side airplane data.
EICAS simplifies flight deck clutter by integrating the many electro-mechanical
instruments that previously monitored engine and aircraft systems. Safety is increased whilst the pilot workload is simplified. EICAS continuously monitors the aircraft for out-of-tolerance or abnormal conditions and notifies the crew when
an event occurs.
Electronic Centralized Aircraft Monitor (ECAM)
The pilot’s workload on all aircraft includes continuous monitoring of the flight instruments and the sky outside of the aircraft. It also includes vigilant scrutiny for proper operation of the engine and airframe systems. On transport category aircraft, this can mean monitoring numerous gauges in addition to maneuvering the aircraft. The electronic centralized aircraft monitoring (ECAM) system is designed to assist with this duty.
The basic concept behind ECAM (and other monitoring systems) is automatic performance of monitoring duties for the pilot. When a problem is detected or a failure occurs, the primary display, along with an aural and visual cue, alerts the pilot. Corrective action that needs to be taken is displayed, as well as suggested action due to the failure. By performing system monitoring automatically, the pilot is free to fly the aircraft until a problem occurs.
Early ECAM systems only monitor airframe systems. Engine parameters are displayed on traditional full-time cockpit gauges. Later model ECAM systems incorporate engine displays, as well as airframe.
An ECAM system has two CRT monitors. In newer aircraft, these may be LCD. The left or upper monitor, depending on the aircraft panel layout, displays information on system status and any warnings associated corrective actions. This is done in a checklist format. The right or lower monitor displays accompanying system information in a pictorial form, such as a diagram of the system being referred to on the primary monitor.
The ECAM monitors are typically powered by separate signal generators. Aircraft data inputs are fed into two flight warning computers. Analog inputs are first fed through a system data analog converter and then into the warning computers. The warning computers process the information and forward information to the signal generators to illuminate the monitors. [Figure 1]
Figure 1. An electronic centralized aircraft monitor (ECAM) system displays aircraft system status, checklists, advisories, and warnings on a pair of controllable monitors.
There are four basic modes to the ECAM system: flight phase, advisory, failure related, and manual. The flight phase mode is normally used. The phases are: preflight, takeoff, climb, cruise, descent, approach, and post landing. Advisory and failure–related modes will appear automatically as the situation requires. When an advisory is shown on the primary monitor, the secondary monitor will automatically display the system schematic with numerical values. The same is true for the failure-related mode, which takes precedent over all other modes regardless of which mode is selected at the time of the failure. Color coding is used on the displays to draw attention to matters in order of importance. Display modes are selected via a separate ECAM control panel shown in Figure 2.
Figure 2. An ECAM display control panel.
The manual mode of an ECAM is set by pressing one of the synoptic display buttons on the control panel. This allows the display of system diagrams. A failure warning or advisory event will cancel this view. [Figure 3]
Figure 3. Nine of the 12 available system diagrams from the ECAM manual mode.
ECAM flight warning computers self-test upon startup. The signal generators are also tested. A maintenance panel allows for testing annunciation and further testing upon demand. BITE stands for built-in test equipment. It is standard for monitoring systems to monitor themselves as well as the aircraft systems. All of the system inputs to the flight warning computers can also be tested for continuity from this panel, as well as inputs and outputs of the system data analog converter. Any individual system faults will be listed on the primary display as normal. Faults in the flight warning computers and signal generators will annunciate on the maintenance panel. [Figure 4] Follow the manufacturer’s guidelines when testing ECAM and related systems.
Figure 4. An ECAM maintenance panel used for testing and annunciating faults in the ECAM system.
Engine Indicating and Crew Alerting System (EICAS)
An engine indicating and crew alerting system (EICAS) performs many of the same functions as an ECAM system. The objective is still to monitor the aircraft systems for the pilot. All EICAS display engine, as well as airframe, parameters. Traditional gauges are not utilized, other than a standby combination engine gauge in case of total system failure.
EICAS is also a two-monitor, two-computer system with a display select panel. Both monitors receive information from the same computer. The second computer serves as a standby. Digital and analog inputs from the engine and airframe systems are continuously monitored. Caution and warning lights, as well as aural tones, are incorporated. [Figure 5]
Figure 5. Schematic of an engine indicating and crew alerting system (EICAS).
EICAS provides full time primary engine parameters (EPR, N1, EGT) on the top, primary monitor. Advisories and warning are also shown there. Secondary engine parameters and nonengine system status are displayed on the bottom screen. The lower screen is also used for maintenance diagnosis when the aircraft is on the ground. Color coding is used, as well as message prioritizing.
The display select panel allows the pilot to choose which computer is actively supplying information. It also controls the display of secondary engine information and system status displays on the lower monitor. EICAS has a unique feature that automatically records the parameters of a failure event to be regarded afterwards by maintenance personnel. Pilots that suspect a problem may be occurring during flight can press the event record button on the display select panel. This also records the parameters for that flight period to be studied later by maintenance. Hydraulic, electrical, environmental, performance, and APU data are examples of what may be recorded.
EICAS uses BITE for systems and components. A maintenance panel is included for technicians. From this panel, when the aircraft is on the ground, push-button switches display information pertinent to various systems for analysis. [Figure 6]
Figure 6. The EICAS maintenance control panel is for the exclusive use of technicians.