Power Plant

Question 1

EEC?

Answer 1

It’s the FADEC, in 738 speak

Question 2

Soft alternate “mode” of EEC?

Answer 2

If required signals are not available to operate in the normal mode, the EEC automatically changes to the soft alternate mode. When this occurs, the ALTN switch illuminates and the ON indication remains visible. In the soft alternate mode, the EEC uses the last valid flight conditions to define engine parameters which allows the mode change to occur with no immediate change in engine thrust. Thrust rating shortfalls or exceedences may occur as flight conditions change. The soft alternate mode remains until the hard alternate mode is entered by either retarding the thrust lever to idle or manually selecting ALTN with the EEC switch on the aft overhead panel.

FCOM 570 for more.

Question 3

loss of either DEU results in:

Answer 3

loss of signal to both EECs. The EEC ALTN lights illuminate and each EEC reverts to the alternate mode to prevent the engines from operating on a single source of data. FCOM 570 for more.

Question 4

HARD alternate mode of EEC Failure

Answer 4

When the hard alternate mode is entered, the EEC reverts to the alternate mode thrust schedule. Hard alternate mode thrust is always equal to or greater than normal mode thrust for the same lever position. If the hard alternate mode is entered by reducing the thrust lever to idle while in the soft alternate mode, the ALTN switch remains illuminated and the ON indication remains visible. When ALTN is selected manually, the ON indication is blanked

Question 5

EEC protects engine or doesn’t?

Answer 5

N1 and N2 speed, yes. EGT, no.

Question 6

EEC idle modes

Answer 6

Ground, Flight, Appch.
Appch mode when in flight if flaps are in landing configuration or engine anti–ice is ON for either engine, and stays on until on ground.