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31-42-00
ú ú 05 Page 2 ú Mar 15/89
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
B. Functional Description (Fig. 2)
(1) The EIS Primary Display receives, processes, and displays the primary engine parameters of N1 (both limit and actual), N2, exhaust gas temperature (EGT), and fuel flow/fuel used (FF/FU) for two engines. For EFIS configured airplanes, it also displays engine thrust mode annunciation (TMA) input data from the flight management computer (FMC). In addition, it provides the following special features:
(a) Output Functions:
1) All displayed engine parameters are transmitted on an ARINC 429 digital ouput data bus to be read and used by any system requiring engine information, such as a flight recorder system or an ACARS system.
2) An independent analog output of actual N1, EGT, N2 and FF parameters for use by digital flight data acquisition unit (DFDAU).
3) An N1 valid output signal for each engine to stall warning computers and flight control computers.
(b)
Abnormal Start Indication (ASI) - The Primary Display will detect impending hot start (excessive exhaust gas temperature) or hung starts (failure of the engine's high pressure compressor to accelerate). If either condition is detected, the EGT digital counters on the display will flash to alert the flight crew of the impending abnormal start.
(c)
Programmable Engine Red-line Limits - The N1, EGT, and N2 parameters have limits that should not be exceeded during engine operation; these limits are known as "red-line" limits. When an engine is operating at or above its red-line limit, a visual indication is immediately obvious by means of colored sectors on the display and also by red warning lights. Also, by means of program pins, the Primary Display is capable of displaying four different red-line limits on N1, N2, and EGT.
(d)
Failure Monitoring - The display panel visually indicates to the flight crew any open circuit failures of the N1, N2, EGT and FF engine sensors, by slewing the pointer and counter displays to zero, holding the setting for 2 seconds, then setting the counter display to "dashes" and blanking the pointer display. An electrical short to ground of any analog high signal has the same effect. The loss of digital input data or incorrect parity of digital input data causes the affected display to blank. An invalid or no computed data received by the display unit will cause the affected display to show dashes.
(e)
Internal Relay Circuits - The Approach Idle relay circuit and the Starter Cutout relay circuit for each engine channel enable the relay contacts to signal the N1 Low Idle Warning system and N2 Starter Disengage circuit, respectively.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITH EIS ú
31-42-00
ú ú 02 Page 3 ú Nov 12/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 737-300/400/500MAINTENANCE MANUAL
PRIMARY DISPLAY PANEL
EIS Primary Display Panel Interface Block DiagramFigure 2
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITH EIS ú
31-42-00
ú ú 02 Page 4 ú Nov 12/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
(f)
Built-In-Test-Equipment (BITE) - A software driven BITE facility is initiated by depression of an unmarked bezel-mounted button. When initiated, the BITE facility exercises all major functions derived within the instrument. This facility is inhibited if either engine %N1 values exceed 10% rpm.
(g)
Engine Exceedance Recording and Storage - A maintenance module inside the display monitors the N1, N2 and EGT of both engine channels. On detection of an exceedance in one or more of the parameters, the EIS Primary Display unit stores the actual parameter values of N1, N2, EGT and Fuel Flow for that engine in a battery-backed RAM. This information is also stored during an abnormal engine start condition. Information stored in battery-backed RAM may be retrieved and erased by an external command signal while power is applied to the unit.
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