737 Flight Crew Operations Manual
Engines, APU -
Engine System Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
7.20.4 D6-27370-866-EGP
If the compact engine format is displayed, the subsequent exceedance of a
secondary engine parameter will cause a rectangular box outline to appear around
the secondary engine parameter. For the initial 10 seconds, the box outline is
displayed with thick lines and the box blinks. After 10 seconds, thinner lines are
used for the box, and the box stops blinking. The color of the box will match the
color of the digits of the exceedance: amber box for an amber exceedance, red box
for a red exceedance, and white box for an exceedance indicated by reverse video.
Once all exceedances are removed, the box outline will be removed. For multiple
exceedances, the color of the box color will match the worst case exceedance.
Electronic Engine Control (EEC)
Each engine has a full authority digital EEC. Each EEC has two independent
control channels, with automatic channel transfer if the operating channel fails.
With each engine start or start attempt, the EEC alternates between control
channels. The EEC uses thrust lever inputs to automatically control forward and
reverse thrust. N1 is used by the EEC to set thrust in two control modes: normal
and alternate. Manual selection of the control mode can be made with the EEC
switches on engine panel.
EEC Normal Mode
In the normal mode, the EEC uses sensed flight conditions and bleed air demand
to calculate N1 thrust ratings. The EEC compares commanded N1 to actual N1
and adjusts fuel flow to achieve the commanded N1.
September 26, 2013
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